50
Microcomputer Business Applications
Howard M. Bunch, Robert M. Scher, Paul W. Vickers
Department of Naval Architecture and Marine EngineeringThe University of Michigan
August, 1984
Nr,Y.v",,>I 5-; r .;..',Y r�:-pod'YORY MICHU-SG-84-603$4.00
Michigan Sea Grant College Program � Publications Office2200 Bonisteel Boulevard - Ann Arbor, Michigan 48109
TABLE OF CONTENTS
INTRODUCTION
PREPARAT1ON FOR COMPUTERIZATION
OVERVIEW OF BUSINESS APPLICATIONS
ACCOUNTING APPLICATIONS
ACCOUNTS RECEIVABLE/PAYABLE PROGRAMS
GENERAL LEDGER PROGRAMS
WORD PROCESSING PROGRAMS
DATABASE SYSTEMS
12
14
17
19
19DATABASE ORGANIZATION
DATABASE FILING AND RETRIEVAL OPERATIONS
DATABASE ARITHMETIC OPERATIONS
DATABASE OUTPUT OPERATIONS
21
23
24
25
29
LIMITATIONS OF MICROCOMPUTER DATABASE SYSTEMS
CODING SYSTEMS
LIST OF FIGURES
RECORD DESCRIPTION SHEET
2. A TYPICAL BOATYARD'S BUSINESS SYTEM FLOW DIAGRAM
3a. ACCOUNTS PAYABLE REPORT
3b. VENDOR PURCHASE ANALYSIS, 1099 FORM, CHECK REGISTER
3c. INVOICE REGISTER, MANUAL CHECK REGISTER
SINGLE-ENTRY ACCOUNTING SYSTEM
5a. DAILY TRANSACTION JOURNAL, DETAIL REPORT
5b. CHART OF ACCOUNTS, GENERAL JOURNAL ENTRY REPORT
5c. TRIAL BALANCE
6. DATABASE MANAGEMENT ORGANIZATION
7. TYPICAL DATABASE INPUT SCREEN
8. DATABASE OUTPUT SCREEN
9. CODIFICATION-INFORMATION USE ANALYSIS BY FUNCTION
10. REFERENCED AND HIERARCHICAL CODING
Sa
14a
14b
14c
15a
15b
15c
158
21a
25a
25b
30a
31a
The wide 1 v recoqn i zed va 1»e of the mi c roc om pii ter in the em' 1 I -hus i ne ss
settinq has heen perhaps the greatest sinqle factor in the recent qrowth of.
the market for sma1 1 computer svstems and sof tware . 0 qlance at any of the
popular maqaz ines on mi crocomputer techno loov will show that hus i ness
apnlica t i ons, the use of the computer for typical of f ice-oriented wor k, now
cons ti tute a predomi nant par t of. hoth the. hardware and so f tware marke ts .
<on ver se 1 v, for man v small firms, hus i ness applications are the pr i mar v reason
f or acq»i ri nq a micr ocomp» ter . In fact, in mos t small hus ines ses, qene ra 1
applications in the husiness of fice remai.n the primarv soiirce of. pavhack Rue
to computerization, ra ther than more specialized enqi neer i na or sci enti f ic
uses. It is of ten true, therefore, that a small maniifacturinq firm mav heqin
with husiness applications as the surest rationale for comnuterizinq, and
suhsequen t1 v realize, almost as a hy-product, the potential henef i t s to he
qained hy computer applications in enqineerino or production.
It is not surprisinq, then, that for most manaqers the first contact
wi th microcomputers is like 1 v to he in the field of. husi ness applications:
book-kee pi nq, accouh tinq, word-process incr, inventor v and pa vro 1 1
record-keepinq, and other every-Ray of fice work, J or this reason the process
of fir st introducinq the computer into a small hiisiness often occiirs in the
husiness of f ice, rather than in enqineerinq or oroRuction ..Ws a riile, this
introduction also implies some restructurinq of ofFice roiitines. The prohlems
that can arise in the course of this process are therefore iis»all v related to
the everyday operations of the husiness of tice. Very often, such -nrohlems
arise fr om an incomplete anal vsis of existinq of f ice procedures, or from
nai ve expec tation that a compiiter wi 11 automatica1 1 v or rather, mani ca 1 1 v!
streamline proced»res, reduce the volume of. paperwork, eliminate Rup] i ca ted
ef fort, and ens»re rapid access to all needed information hy all interested
parties. In fact, witho»t a qood deal of earnest human tho»oht .ef ore
installinq the computer, quite the opposite effects can occ»r, and have.
General ly, however, if a manaqer beqins with acc»rate concepts of what
computer system can Ro for him, and what it needs From him in order to work
well, the results will he more reasonable expectations, an order 1v transition
period, and a succe ss f ul ins ta 1 la tion that wi 11 reco ver its own cos ts ver v
quickly.
Before we even heqin an overview of the vario»s kinds of h»siness
applications, therefore, we will look insome detail at the process of
hrinqinq a computer into the of f ice for the first time. Wo kev concepts
e spec i a 1 1 v importan t Rurinq the oeri od of st»R v tha t should orecede the
installation of any computer svstem. These concepts are based on some
recoqnition of how comp»ters function, althouqh of. co»rse it is not necessarv
to understand the internal workinqs of the svstem in order to»se it
correctly. If it were necessarv tor the averaqe evervdav user to become
computer scientist, the "computer revo1»tion" as we have come to know it wo»ld
never have taken place. !
9'irst, with reqard to svstems that do ro»tine business calo»lat ions, such
as acco»nti nq proqrams, for example, there is no essential Ri F f erence between
the wav a computer treats the numhers and the way a person would handle them
i n a conventional accounti nq procedure . However, in or Rer to ins tall a svs tern
that wi 1 1 do the work ef f iciently, the manaqer must he able to describe the
procedure in such explicit Retail that an»ntrained person virt»ally an
idiot! would be able to understand it, witho»t makinq any assumptions or
inferences. 'Vhe computer is just s»ch an iRiot. it will not assume or infer
anvthi na, which ma v seem a qrea t inconvenience at t i r st, b»t wh irh, on
ref lection, is real 1 y the supreme virt»e of obeR ience . It is the onl v wa v
tha t a mana qe r shou lR wan t. a compute r to he . !
second, wi th reqarR to svstems tha t store anR retrieve inf ormation, s»rh
as Ratahase nroqrams, it sho»lR he kent in minR tha t the comn»ter svstem
"remembers" information in a hiqhl v strurt»reR wav that Roesn' t al ~ave
resemble ei ther human memory the Reta i ls of which Re f v Rescription !, or even
a conventional f i 1inq svs tern. %is is tr»e berause, in human tho»qht anR in
the conventional file Rrawer, spatial anR temporal relationships are the most
obvious anR convenient ways to orqanize the worlR. In a file Rrawer, for
example, when we want to aRR new inf ormation or even a comnlete1 v new fi le !,
we just push two adjacent Ror»ments or folRers ! apart at the req»i reR nlare,
crea tinq an empty space just where we want it. we then slip the new mater ia 1
into that space, anR the filinq oneration is Rone. qimilarlv, to remove or
replace unRa te! inf orma tion alreaR v in the file, we qo t o a oar ti cular place,
oerf arm a physical lv obvious action, anR it ' s clone.
In qeneral, however, computers Ro riot perform memory operations in such
physically meani nqf»l wa v. Computers have no intr i ns ic concepts of nLace,
soatial relationships, for Rata . In fact, two se ts of. inf ormation that
human he inq miqht picture as occ»pyina aR jacent file folRers mav be storeR in
complete lv senarate reqions of the system. %lever the less, with the proper
s vs tern for stori nq and recoveri nq the in f orma tion, the human opera tor is free
to have to have his own human conceptualization of. "where" the Rata is, whi le
the computer wi 11 take care of its own internal arranqements . Obvious 1 v, both
the computer and the user wi 1 l, have to aqree on some thinqs, such as the
iden ti tv of the element of in formation heing stored or re tr ie ved, and what it
is .supposed tn con ta in. Thus, »neer s tanning t he concepts of. corn p»ter acces s
to information may require a more ahs tract wav of thinkinq than a oh vs ical
filinq system usually demands. Accordingly, it »s»ally also requires more
pla nninq in advance. Some de tai ls of. this pla nni nq wi 11 he discussed at
greater Length suhsequentlv.
With these two notions, namelv, the similarity of calculational chores
and the dissimilarity of memory structure, we will now examine the process of
preparinq for computerization in the of f ice. We will then t»rn to a hroaA
overview of application areas for the husiness environment.
PRF'PARATIOM FOR COHPOTFRIyiA+IOM
The ke v to success f u 1 intr od»r tion of. a mi rrocomp»t e r-based sytem into
anv business is planninq. The purchase of a microcomputer should be recrarded
in tAe same way as anv othe r ma j or investment, with rare f ul consideration of.
the functions that the new aequi si tion is supposed to per f orm, and how it wi 11
be used. It can hardlv be too stronqly emphasized that the comp»ter is not
black box that wi 1 1 automa ti ca 1 1v cut costs and increase prod»r ti vi t v. Like
manv other capital improvement, the computer is mere lv a tool, and it wi ll
only work well if. it is applied corrertlv and to the riqht jobs.
Like all computers, the mirro can be used to qrea tes t advantaqe in
"system" environment, that i.s, in a sit»ation where of f ice routines aro well
es tab li shed, and man aqeme n t inte r ven ti on is suppos ed to be the excp mt i on
rather than the rule. In order to fit anv new member even a human beina!
i nto the picture wi th a minim»m of di s ruption it is ver v important to orqan i ~e
the work into a set of fair lv speci f ic, self -contained routines. These can be
assiqned in an appropriate order, so that the new member of the svstem can be
observed and c:orrec ted as the learninq process qoes on. Of cour ~e, when the
new arrival is a computer rather than a person, the necessit v For well
defined, discrete units of work is not merelv a convenience, it is an absol»te
necessi ty. Only when the»ser has identif ied and defined the applirations ran
he beqi n to ma tch the machine, ocr i phera ls, and oe rhaps most impor tant l v ! the
sof twa.re for his own of tice applirations.
The f ir st ste p in planninq f' or comp»te ri @ation is to determine how vour
office operates riqht now, in detail. This mav sound obvio»s, and perhaps
tri vial, but the level of detai 1 required for the most ef f icient start»p of
COmputer SVStem iS Substantial, and it iS Often Surprisina hOw complicated a
supposedlv "simple" procedure really is, when it is broken down into its more
basic elements. The class ir. example, of co»rse, is to desrr ibe how to tie
your shoes.!
In the case of of fice operations, however, the basic element is the flow
of a unit of. information. There are six fundamental questions to be asked
about each movement of i.nformation into, thro»qh, and out of the of f ice.
These are: Who? What? Wher e? When? How? Why? These ques tions sho»ld
asked and answered about each of the everydav information transactions +>at
goes on wi thin the of f ice� . In other words, the user must Ref inc, qui te
explici tly, the identi tv, source, Res ti nation, schedule, ~cans, and mat i vation
of. all the standard forms of information fiowing through the of fice. Me
process may be described as gathering information abo»t information.
The obvio»s place to begin is in the file cabinets. All routine renorts,
work orders, invoices, anR other typical paperwork should be examined and
ca ta loqued . ~i a»re I may ser ve as a quiRe to the kind of in f or ma tion vo»
should be lookinq for when you review a par tic»lar type of Rorument.
obviously there is no need to review everv record in the place. In fact, i»st
a few examples from every cateqorv will s»f fice. Ln order to see what kinds
of forces may be at work within your existing svstem, however, it mav be a
good i Rea to look at examples of a given tvpe of document from dif ferent time
periods, generated by Ri f ferent staf f members, and related to di f ferent ~obs
Changes in format or content, whether these rhanges resulted due to an
"of firial" policy derision, a change in personnel, or nothinq but random
personal whim, should be noted. If a "routine" has been established at some
time in the past, anR it has changed over the co»rse of time, there should be
a reason, and a manaqer should be interes ted in whv it Rid rhange . Qf course,
RECORD DESCRIPTION
Date:Completed by:
Record Name:
Name Department
Originator s!:
Destination:
Description of Record:
Information Description:
Alphanumeric Length of DescriptorNumeric English
Purpose:
Frequency:
-6a-
FIGURE 1--Record description sheets, such as this, will aid
in the introduction of the microcomputer by standardizing reports
and smoothing information flow in the organization.
here never was any real routine, a manager might also want to know that,
especially if he is considering a move into computerization.
During the record cataloging process it is use f ul, nay, imperative, to
inter view some of the people who most frequently or iqi nate and recei ve the
typical documents that you' ve found. The most important ques tions to ask them
include the following:
How many of the s e documents do you see in a week? Do you tend to see
them on a fairly steady basis, or do they come in concentrated batches?
How long does it take to complete this document? Note that "completing
a document may ref er to wri ting it, reading it, or acting on it. ! Do you
usually have to complete the document under time pressure?
What addi tional information do you need to get to complete this document?
Where do you get this additional inf ormation? Is this information always
available in a form that' s convenient for helping you process the document?
I s the inf orma tion usually accura te enough f or your purpos es?
What else needs to be done bef ore you are free of this document?
Who or where do you get it from? Who or where do you send it to? Do the
documents you recei ve as a matter of routine usually contain all the
information you need to process your other documents, or to do other parts of
your job? What other information should be sent to you on a routine basis?
Conversely, do you routinely get a great deal of superfluous information?
If so, does this interfere with or mask" the necessary information?
. he next step in pre para ti on is the eva 1»ation of the cata. loaned record s
and the accompanyinq interviews. lt is of ten convenient to draw a chart of
the information flow in the company. L typical administrative flow chart may
follow the example of Fiq. 2. <o arrive at a reasonablv complete, but still
under standable, picture of the company ' s inf ormation flow, it is neces sar v to
start with a very larqe-scale, over-all view, on the order of Fiq. 2. 'This
larqe-scale information map sho»ld lend itself to a fairly straiqht~orward
division into a niimber of sub-seqments . If not, then it ' s possible t hat the
orqanization itself is not systematized in the best wav. ! On the level of
these sub-seqments, the flow chart mav be expanded to the level of oriqinat ors
and rec i pien ts of the var io»s kinds of documents .
How, qiven the cataloqued records, the interview results, and the flow
charts, it is time to ask some hard <iestions. noes the present system work
as well as its participants feel it should? >Jhat are its identif iahle
weaknesses and stronq points'? Is there a redunRancv of effort in di f ferent
areas of the orqanization? How convenient is it to f ind the reqiii red
i nf ormation when it is needed? Are there anv consistent bott lenecks of
information? Is there a problem with accuracy of documents from anv area?
Are ther any obvious holes in the svs tern, or parts of the sys tern that seem to
work only because of informal intervention by key individuals? &is kind of
human orqanizational "maqic" is extremelv difficiilt to replicate by corno»ter
unles~ it can be def ined in a very explicit way. !
An honest. and informative evaluation of the present system will ease the
i ntroduction of the microcomputer into voiir of tice . As a vile, vou should
beqin to make any chanqes in procedure that may seem helpful at an earlv
s taqe, be f ore br i nqi nq in the computer . It is an advantaqe to have ocr sonne1
qet »sed to any chanqes in procedure beFore thev are Faced with a new,
unfami1 i ar, and verv central participant in the of fice�. Af ter. some st»R v, I t
may he possible to red»ce the number of standard document tvnes, to eliminate
red»ndancy, and perhaps to outline anv new Roc»ments or reports that mav be
initiated af ter the arrival of the comp»ter.
I t is impor tant to remember that man v people are s ti 1 l qui te
uncom f or table with the idea of a computer: thi s is par tie»la r I v tr»e if. t he v
feel that the machine wi ll in some wav be "takino over their job." It is
important to reassure the people who will be handlinq the new svstem that the
computer will be there as an aid to them, not a replacement for them.
The next. staqe of advance planninq For compute ri zation, and it is
overlooked surprisinqly often, is Reve lopinq a work space for the comp»ter.
The most important attributes of a micr ocomputer work station are environment,
storaqe, operator comfort, and access. obviouslv, these factors are import ant
in almost ever v part of the of f ice but they become even more crit ical or
computer and the people who wi ll be worki nq with it .
'The microcomputer work center sho»ld have a cool, clean air suppl v. The
computer is itself a substantial heat source, and both the processor and manv
peripherals are sensitive to both temperat»re and dirt. lf there is anv heavy
electrical equipment in operation nearbv, the microcomp»t er mav require
surqe suppressor to control voltage to the machine. Static electricitv can
damaqe the information on a maqnetic Risk; antistatic carpe tinq is one
possible solution. Because most micros fit easily on a desktop, the space
requirements for the machine alone are not qreat. however, manv new users
mav tend to for»et the additional ~pace required for external Risk drives,
orinter, plotter, bookshelves, and storaqe cabinets, which adds»p to a fair Lv
large floor-space, much bigger than one desk.
Remember. also that for convenient »se i t. wi 11 he neces sar y to give the
operator enough work space to kee p some input and ou tp» t ma te r ia ls laid o»t
for ref erence, as well as the reauired manna.ls and program documentation,
times. This wi 1 1 probably require a single large work table, in add i tion to
the desk holding the computer, and a quickly accessible file rabinet for
storinq disks, etc. The operator should also have access to the bookshelves
and other storage spaces without moving too far� . In addition, the re wi 1 1 be
times when two or more people will need to look at the displav. It is an
ad vantaqe at times to have ample space to do this.
comfortable chair is a neressity for anyone using a keyboard for anv
length of time, obviously. Other environmental factors are glare from the
video display due to liqht re flections, and eye fatigue d»e to the disnlav
itself .
further element of the planning process is to ronsider who will have
access to the machine, on what schedule, and how that access «ill be
controlled. A scheduling system for training and everydav use is very
desirable, and should be sketched out to some level of. detai 1 even bef ore the
machi ne is brouqht in. The sched»les can, of course, be ad j usted later as
experience dicta tes, but you should "e pre pared f rom the outset. 4 log-in,
log-out system will aid in developinq a workable permanent schedule, while
an advance sign-up sheet may help avoid conf lirts and wasted time.
Having prepared in advance, the trans i ti on to a computer ized of f ice
system ran in fact be made with a minimum of disruption and pain. Of course,
there remains the matter of hardware and sof tware selection, a proces~ which
usually qoes on concurrently with the preparations described above. The
f ollowinq sections of this paper outline some of the applications of the
microcomputer to the business of f ice, while other papers in this series of fer
more detailed introductions to both the hardware and sof tware areas.
In any case, the overall financial success of vour install.ation depends
in qreat measure on the ease with which you can work the machine into your
system. Farly setbacks are not irredeemable, of course, but you should
remember that if you allow the computer to disrupt. a workinq off ice, even for
a few weeks, you will have in effect added a substantial amount to the
purchase price of the system. As stated before, the microcomputer can be a
money maker, and it can more than pay its own way if it is used riqht.
However, there is no neeR to challenqe both yourself anR the machine bv
imposinq a handicap durinq the star tup period, especially when this can be
avoided to a qreat extent bv some advance effort in thinkinq and planninc
before the computer arrives.
-1 1-
OVERVIEW OF BUS INES S APPLICATIONS
In this section we will present a general Rescription of some of the more
important applications of the microcomputer in the business off ice. The
purpose of this brief survey is to outline some of the more impor tant
applications of microcomputers in the small-business set tinq. The Retails of
speci f ic hardware and sof tware on the market is hest lef t to the relevant
owner' s manuals and program documentation. However, this brief survey mav
provide some quidance for the selection of applications proqrams for a
particular office environment.
Accountinq Applications
Accounts Receivable/Payable Programs
In justifying the acquisition of a microcomputer, the accountinq function
is probably the greatest initial source of benefits in the small-husiness
settinq. A system that can assist in computinq balances, updating, verifvinq,
and printing hills and statements, maintaininq an un-to-date record of cash
requirements, writing and recording checks and purchase orders can often pav
back the entire installation cost in a relativelv short period . In fact, the
business use of the computer in the accounts-receivahle/pavahle function
remains the moet impOrtant sinqle application for manV Small-business
microcomputer users.
Potential savinqs due to computerization of the accountinq function arise
from two principal sources. First, accountinq svstems can help management
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control cash flow. Accurate and up-to-date evaluation of the comapanv' s cash
position can of ten prevent short-term financial problems from arising due to a
lack of current information, in other words, clue to knowina too little too
late. Second, the computer svstem can save accountinq ef fort by faci litatinq
Rata entry and verif ication, obviously speedinq the routine calculations, and
by reducinq and localizing errors. These two benefits are clearly relateR:
the high speed of the system allows rapid Rata retrieval and manipulation,
which gives management a faster response when an evaluation of cash position
is needed. Manual operations and bookkeepinq expenses can be cut accordinqly,
since onl v the input functions actually require a signif icant amount of
operator time.
The computer performs numerical operations very reliably and accuratelv.
This means that in general, with a verified workinq system of proqrams, the
only source of exror is the input process. If an input veri fication procedure
is used, such as repeatinq each Rata entry and comparinq the two inputs which
the computer can do very quicklv!, then the possibility of introducinq
numerical errors is reduced substantially. Thus, if .the initial input to the
system is regarded as reliable, then all subsequent numerical results are
equally valid . Furthermore, there will be no arithmetic errors to "mask"
any original data flaws. The "self-auditing" nature of the input verification
process also facilitate error location and recoverv, and leads to qreater
accountability.
Machine requirements for an accountinq package vary widely, The most
important variables are: number of accounts, repox'tinq features, invoice and
check-writing characteristics, and auditinq and error-trapping abilitv.
Simple accounts-payable proqrams can run on 16-k machines, while more
-13-
sophisticated sof tware may require 64 k and up. Dual Risk drives are of ten
required. For invoice and check wri tinq, a daisy-wheel printer gives best
results, rather than a dot-matrix type.
When choosing accountinq software the selection is extensive! the hest
course is to consult your own accountant or bookkeeper first. Then, allow
them to review the available software-vendors' literature with you, anR with
the computer or software sales people. Since your accountinq staff will he
the people who will use the system, their opinion on the required features of
software, which in many cases is as much a matter of personal preference as
well as functional business requirements, will be most valuable in the
decision process.
Sample reports from a typical accounts payable proqram are show in the
followinq Fiqs . 3 a-c! .
General Ledqer Proqrams
The qeneral ledger is the source of the majority of financial reports in
the boatyard. The general ledqer can also be the source of hundreds of
headaches for manaqers, accountants, and hookkeepers because of the long,
tedious hours spent trackinq down input and arithmetic errors. Among all the
accountinq functions the qeneral ledger is the most time consuminq and
critical to the financial health of the yard.
The use of the microcomputer to assist the bookkeeping process and
maintain an accurate qeneral ledqer is a very straightforward and cost-
effective application. The microcomputer can cut bookkeeping time
requirements siqnificantly hy allowing for detailed audits, error recovery,
-14-
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BAKERJOHN K.LOS ANGELES HOSP ITAL
000118 05/15/S20001 19 05/15/82 1000
4 000120 05/15/S2 1020.00 21019 9921019 99e e e REPORT TOTAl e ea
Fj GURE 3b Tise Vendor Pun&ran by vandnr as wa» aeAnalysis pn vridee a a eenarara liednQ of
VENQONPURCHA88AlCALYSII Snnmaryofpwnhaeee aeratumenrOradea.
5,548.92 '.00 - - .'01 ~ 586~ 1 1, 001 l07 65'' ... "'.004,OOO.OO - - - .OO ~lq 515 97 - 006,000 00;, 002e470 00 00
900 00 ..-, .50 756 871 56 ' .- '. '- ~ 004',750.00,,=': �.'-'.".00 . -:.- 44!851 75 . -;XRK00':
10s 000-00' ~ .-"' '~00
49' Ool a 96'-, . X!K.75-- :.:: a
FIGURE 3cThe awaice ~%ovid' a Iisting oi am lhe eIrpem throrrghevoiCee entered into InvoiCe Data Enter
01
-Of OO
- - -The eyttam'errppcia " 'RHeap an axeurrgng
MAMMAL CSCSCK RSOls'l%R-
Hantivrittenohecka ' mrrNPA-bertt--~ eatppenmred - -. acomia wtgleeimplehrar the etiam.;-, "hier corwr».'-. - ..
A~counte Payabrte R~porte-
and double-entry accountinq. Balance sheets, income and expense statements,
and other specialized reports can of ten be prepared in a matter of minutes,
rather than Rays.
In a computerized qeneral ledqer system, the account Rata is usually
contained in a master qeneral ledger file, or it can be combined with other
f inancial proqr am Rata f i les, such as accounts recei vahle/pavable, oavrol 1, or
even inventor v data, to form an inteqrateR sinqle-entry svstem, as shown in
Fiq. 4. General ledqer systems are usually hiqhlv interactive. The system
provides the operator wi th prompts for the information to be inserted, or
displays a menu from which the user can choose the Resired repor t or format
for input or output. Reports can be either custom desiqned or follow a
s tandard format. Sample reports from a typical microcomputer-based qener al
ledger proqram are shown in the followinq Fiqs. 5 a-c! .
Memory requirements for supportinq a qener al ledqer svstem are dependent
on the number of entries to be maintained in memory at a qiven time. This
requirement can usually be estimated by reviewinq your existina books. In
certain cases, also, the machine requirements will Remend on the level of
sophistication of the computerized accountinq svstem. For example, if the
qeneral ledqer proqram forms part of an inteqrated system with other
accountinq proqrams, such as oayroll or accounts receivable/pavable, to allow
for single-entrv accountinq, the memory requirements will be increased
considerably, 128 k beinq the norm for such inteqrated svstems. In spite of
the recent decreases in memorv costs, compared with other system components,
memory requirements can still be a critical factor in Reterminina the
selection of hardware and software, althouqh this may no lonqer be true
several years from now.
-15-
FIGURE 4
Single-entry accounting systems can simplifythe introduction of the microcomputer intothe boatyard business office. Each program,represented by a different shaped box, can"stand alone," yet each program communicateswith the general ledger program.
FIGURE Sa
DAILY TRANSACTION JOURNAL
G3r 31/82GENERAL
POST tNGS FOR: 03/
SOURCE JOURNAL'r CDESCRIPTION8/L NO.
CASH IN BANKACCOUNTS P4VASLECONTRACTS PAVABLNO'fES PAYABLE
l ri1-r.vari201-00ZO? in- OS-GG
JOURNAt TOTALr
SOURCE JOURNALS CR8/L NO DESCR IPTI-ON
iI 0 1'~O - CASH IN BANK105-00 ': ACCOUNTS RECEIV
.JOURNAL, TOTALs
--'-,.� SOtJRCE JOURNAL f PR8/L NO~' ~: DESCRIPTION
!emfarl~ - CASH. TaL BANK?10~0 ''... - FEDERAI- &/ff TAftES
"- F. I . C. A. l AXES - PA501 ~ �.. � SAL'4R I.ES. '505~ -,: .;-' PAYROLL TAXES%10~ ' '.' - FRINGE' BEMEF ITS
I' ' JOURNAL." TOTAL I
SOURCE JOURNAL: S JG/t. NO. �, DESCRIPTION
C4SH IN BANK
complete lrshng of aliThe General Ledger transacsiorls affectlrlgDetail Report i ~ a the General Ledger. Reference number Reference remarkDETAIL REPORT
03/31/82
DATE REF
101-00 C
02/28/82- CD JV 15. /' CASH DISSURSENENTS02/28/82 CR JV-14 / CASH RECEIPTS02/28/82 PR- JV 17'; ./ PAYROLL02/28/82 SJ JV 13 - / SALES JOURNAL.
85i 51n. 8267r465i 60
7;315.82.5i 734 60'
lgr626. 44123, 222'. 04
NET' POSTIN6 FOR PERIOD fENDING .BALinNCEs
ACCOUNTS RECEI VABLE
n4t ANCE FOR4/AR Total of activity forperiod
Tfie Dariy Transaction thereby providing anRegister summanzas audit trail from the Souroe Journals Cashall coatings to the various Source Disbursenafnts. Cash Each Source JournalGeneral Ledger, Journals. Reornpts, payroll, etc.! is in balance
FIGURE Sb
OI.'MORAL JOURNALKNlMY RRPIÃlT
~ m/is r
~ POSTXDATE
SJ SALES JOURNAL
DESCRIPTION
05/ZI/a2 Jv- Iz
8/L NO
5i734 60B9, 445. Z2
25' 655 ' 0421 ~ 524. B412,4!9. 50
154. 777. 52 154, 777. 52aac&aea
03/51/82 JV 14 CR CASH RECEIPTS
8/L NO DESCRIPTIUN
01 AA
101~10~12~11~2120M'2~401-OO402~403-OO451~452~4~~
CASH IN BANKACCOUNTS RECE I VABLEINVENTORY � PRODUCT AINVENTORY � PRODUCT B .INVENTORY - PRODUCT CSALES TA X PAYABLESALES � PRODUCT ASALES � PRODUCT 8SALES � PRODUCT CC. O. S � PRODUCT AC. O S � PRODUCT BC. O. S. � PRODUCT C
FIGURZ 5c
At any bme you may~ a Tnal Batsnc» General Ledger isindicabng tbat your m baganda.
P
STATE OF THE ART1RIAL BALANCE FOR PERIOD ENDINB 05/51/B2
DATEt 05/51/82
BEBINNINB'~RALPetCE
ACCOUN Tl4PIBER ACT ZV I
e~essa~~~nrmarsRI~~wm . > ~~ '.~~r~ a ~s~
0 101~I OS~1 05~011~012~1
, ~ 12~21~5
151~
CASH IN BANB:PETTV CASHACCOUNTS RECEI VABLENOTES RECEIVABLEINVENTORy - PRGBUCT 4INVENTORY PROIDUCT BI NVENT ~Y � PRODUCT CLANDBUILD INS .AUTOS h TRLXXSEQU I ~:
~TTtmP L a'+
142, 848~ 48147. 50
89,295. 9910,000 0052, 069. 3746,941.60l5,392 30"-B5, 510.81
105r &i 005'I ~
19. 626- 44CR- 125, ~. 04. 00 147
22 179. 72 111,475,71~ OO - 10r000 OO
1,914. 74 . 55, 984. 114~784.84CR- 42,156 76
11.962.75CR
In war kinq with a computerized qeneral ledqer it is vital for the
operator to be aware of the use of storaqe space, that is, how much memory is
available in the system at any time. In some sof tware arranoements, an entire
accountinq system can be interrupted crashed! if the operator attempts to
enter more data than the proqram can store. The entire proqram will then have
to be restarted, and this procedure can he lengthy, especially with larqe
amounts of Rata to be recovered from disk. Protection aqainst this kind of.
crash is one impor tant feature of more sophisticated accountina sof tware.
Obviously, therefore, it is crucial to make sure that the sof tware vou
acquire has enouqh entry space available for your current needs, plus a
reserve. Furthermore, because your requirements may expand into this reserve,
a backup system should be incorporated which will tell the operator how many
available entries are left, or at least provide an advance warninq as the
system approaches its capacity.
Word Processing Programs
Word processing is a useful and extremely time-saving application of the
microcomputer. Even a relatively simple W-P system allows letters, reports,
orders, quotations and specifications to be written, edited, and printed far
more quickly and accurately than is possible with a typewriter. word
processing is particularly effective in cases where correspondence, reports,
or other documents are assembled from standardized components. In such cases,
the required pages can be recalled from disk, modified as required for a
particular job, and then printed. '1he advantages of speed and accuracy will
ultimately lighten the load on secretarial staff, although there will be an
initial investment in the effort required to prepare the standard document
modules in advance.
For the usual microcomputer-based W-P system, the system itself is
usually loaded from disk at the beginning of a session, thereafter, the drive
is free to be used for storage and retrieval of documents. However, more
sophisticated word processing programs may a3.so contain dictionaries,
word-break information, and other utility functions. In such cases, the W-P
system disk must remain available at all times, so that dual drives are
necessary.
Desirable features of a word processing program include the ability to
switch the display from page to page rapidly, and to perform editing
operations by individual character, word, line, sentence, paragraph, or entire
page at a time. 'Ihe ability to move entire blocks of text from one place in a
document to another, and to do this conveniently, is extremely valuable.
For standard communications such as requests for vendor information,
forms for regulatory agencies, and other frequently accessed addresses, it may
be useful to maintain mailing lists, or even equigoent lists and the like, on
a disk, to supplement the standard document segments. With such a system,
even the insertion of modifications to standard documents can be assisted by
the compu ter.
Word processing programs can often be used in conjunction with accounting
spread-sheet and database programs, allowing for virtually automatic report
generation. Zn such a combination, a .typical database run can produce not
only the screen output, but also an entire standard report on the printer.
Typical uses for this kind of application may include standard reports on
scheduling, project expenditures, progress, or billings.
-1 8-
Database Systems
Many business operations require access to larqe sets of information:
for billinq, payroll, material orderi nq, planninq, schedulinq, etc.
Typically, this information must be made available to different users for
various applications. Often, each of these distinct applications requires
that the information be accessed and displaved in a special wav, suitable for
the particular need.
In a conventional filinq svstem information is ordinarilv storeR in a set
of filinq cabinets. As each user needs to store or retrieve information, he
must go to the correct ranqe of cabinets, tinR the proper Rrawer, and locate
the desired information in a labeled folder within the file. Database systems
currently available for the microcomputer can be useR to facilitate Filinq
procedures in the business office, and thus to streamline the over-all flow of.
information.
A database is, in effect, an electronic filinq svstem in which user
access time can be measured in seconds rather than minutes or hours. In
addition, the database system keeps track of the file contents, and can
perform all searchinq, collatinq and manipulation of desired data.
Database Orqanization
The primary purpose of the database is to serve as a hiqhlv structured
and rapidly accessible electronic filinq system . From the user's viewpoint,
the basic orqanization of the database is analoqous to a conventional filinq
system.
Inf ormati on i s maintai ned in the Ratahase in the Form of Ris ti net
-19-
records. A record corresponds to an individual file entry, and may refer to
any collection of information describinq a single entity in the file; whether
this is a transaction, a work order, a purchase order, a part, or even a
vessel. In a sense, a record correponds to the material that would normally
be kept in a single file folder in a conventional filing svstem.
The information set contained in each record is stored in the form of.
consecutive fields. Fwch field corresponds to a descriptor, or attribute of
the entity, that is, a parti cular kind of inf ormation about. the enti tv:
date entered, oriqinator, weiqht, cost, vendor, date required, etc.
Obviously, the set of attributes used in a particular database depends
entirely on the nature of the problem. Thus far, the database is in concept
and arranqement almost identical with a conventional filing system.
For reasons of computer memory structure, however, each field must also
have a formal width, that is, the number of characters stored in consecutive
columns within the field, and of ten a type definition, such as real number,
inteqer, alphanumeric literal!, date, or dollar value. These field widths
and types are assigned by the user when setting up the database.
For example, a purchase order record might be set up with the followinq
fields:
-20-
Field Number
DescriptorField Width
Type
Field Number
Descriptor
Field Width
Type
P,,O ~ No9
Numeric
5
Uni t Pr ice
7
$ Value
2
Item Description15
Alphanumeric
6
guanti ty4
Numeric
3
Ve nd or Name
15
Alphanumeri c
7
Total Cost
7
S Value
4
vendor Item No.
20
Numeric
8
Date Ordered
Date
Simi lar records, corresponding to simi lar entities, are stored together
within the database as a file in computer usage ! or a segment. F+ch record
in a particular file uniquely refers to a particular entity, yet each is set
up identicallv in terms of fields. A file is therefore analogous to a file
drawer in a conventional filing system.!
collection of related files, or seqments, constitutes a database. The
conceptual orqanization of a database is illustrated in Fig. 6.
Database Filing and Retrieval Operations
Since the database structure is so closely patterned on that of a
conventional filinq system, the power of the database concept ari,ses from
speed, compactness, and above all, from the abi l i tv to access particular
f iles, records, and fields automatically, according to commands entered bv the
user.
The database management system is a proqram containing a set of routines
to:
�! Keep track of files and file contents.
�! Maintain a cataloq of record formats for all files'
�! Perform specific input and output functions.
�! Perform search and retrieval functions.
�! Perform arithmetic operations on the database contents.
The program is designed to allow the user to perform these tasks with a
minimum of manual effort. The user is required only to issue instructions, or
commands, to the system, tellinq the program which function he wants to
perform, and the program will repond with the appropriate actions to store,
-21�
PURCHASINGREC E IVING SHIPPING
QRQcpcP~>ROLU
eANKING
FIGURE 6
Database Management Organization � Data files, organized by records and fields, are
controlled by a central program which gives the user access to virtually any combinaticm
of file record and field through a series of subroutines.
ACCOUNTSRECE I VIABLE
CCOUN TSPawned E
recall, or manipulate parts of the database.
For data input, as an example, the user first describes the format of a
new file at the time of the initial entry into that file. At this stage, he
must Refine the fields within that file. Thereafter, when making additional
entries into that file, the computer will automatically recall the format,
and will normally but not in all systems! prompt the user to enter the new
information sequentially into the record.
For our previous example, a purchase-order file, the program will first
ask for a purchase-order number, followed by an item description, then the
vendor's name, and so on down the list of fields. The program will monitor
each entry to insure field compatibility, for example, to see that a proper
date entry is made in the "Date Ordered" field, and not some other type of
information. The number of columns in the input may also be checkeR against
the specified field format for the entry.
The utility of the database concept becomes more apparent in the
retrieval and manipulation of data. As mentioned previously, Rata retrieval
in a conventional filing system consists of. opening drawers, searchinq for anR
locatinq or failing to locate! the correct folder, and then finding and
withdrawing the document containinq the desired information. The entire
process is repeated for each document reguired. Often, the documents are also
physically removed from the file space for use at someone's desk. Thev are
then at least temporarily unavailable to other users, and unless a
time-consuminq flagginq system is installeR, onlv the actual user may know
where the required information has qone. Worse, the withdrawn information may
be lost or misfiled on return. 1n a computerized database, by contrast,
documents can be used and displayed without beinq withdrawn from storaqe .
As its most basic use, the database proqram can search for and locate
particular records, copy and collate them, and present them to the»ser in anv
format desired. This simple function is performed by routines that make use
of the orqanization of records within the files of the database.
Recall, however, that the data in each record is stored in discrete,
predefined fields, each of which contains a dif ferent attribute. The actual
data stored within a field on a particular record mav be ref erred to as a
value of that attribute. The user can specif v desired values of any
particular attribute, and instruct the proqram to find only those records
having certain characteristics. Such proqrams are often called relational
database proqrams because of this valuable form of Rata search and retrieval.
The desired characteristics of records can be defined for relational »se
either by specif ic values or ranqes of an attribute. Furthermore, a number of
attributes can be speci f ied at the same time, usinq "AND" or "OR" loqical
operators, to locate a verv specif ic subset of records from the database. On
output or display, records can also be sorted accordinq to values of the
attributes. The order of the sort depends on the user' s specific commands.
That is, records may first be sorted accordinq to values of attribute A, and
within a given value of A, sub-sorted by the value of attribute R. In most
systems, both numerical and alphabetical sort alqorithms are available.
Database Arithmetic Operations
Database proqrams are not necessarily restricted to electronic filinq,
search, and retrieval operations. A number of commercially available database
programs also allow the operator to specify mathematical relationships between
entries in the database in order to create and fill new information sets.
-23-
Consider aqain the example of the purchase-order file. .iven the uni t
purchase price of each item, and the quantitv ordered, the database manaqement
program can compute a total price for each order . The program can add the
number of units or total purchase prices for any number of records, specified
relationally. Thus, the proqram can compute the total number of units of a
particular item description, and the total cost, ordered from a particular
vendor or qroup of vendors !, during a specified period. All of the
information needed to identif v the required records and per f orm the ari thme tie
manipulation is contai ned within the database f ile . ! Thus, database material
can be manipulated by both relational and arithmetic operations at the same
time.
Common arithmetic operations found in tvpical database proqrams include
the four basic arithmetic functions, totals and suhtotals, percent, and in
more sophisticated systems, hiqher math functions and elementarv statistics.
Database Output Operations
A, valuable feature of the database system is the ability to specifv
output. format for a particular run, or for a particular use. There are two
basic types of output available to the database user: formatted and format-
free.
Formatted output is tvpically used for standard reports and other
frequently used database applications. The user must initiallv define the
type and arrangement of output desired. This formatting process is commonlv
referred to as "desiqninq a screen." Typicallv, a "screen" corresponds to an
array of output that can fit on the display at one time, in readable form.
Normally, it also corresponds to an 8-1/2 bv 11-inch sheet, althouqh this can
-24-
be varied at the user's discretion on certain svstems. The user defines the
screen by graphicallv blocking out areas of the Risplav to contain information
from the database, usinq a special system routine, and insertinq anv required
labe llinq or text material that will remain consistent in the report format.
When the screen def inition is finished to the user ' s sati sf action, it is
analoqous to a standard form with blanks for the entry of Rata. The screen,
or standard form, can then be catalogued and saved on Risk for furtheruse.
Typical screen layouts are shown in Fiqs. 7 and 8.
Format-free output is typicallv used in relational-database operations,
such as informal queries, searches, and sorts that are not intenRed to produce
s tandard reports or documents. The data resultinq from the operator ' s request
is simply printed in the order speci f ied by the instruction, without extra
material or pre-specified format.
Limi tati ons of Microcomputer Database Svstems
A wide variety of database sof tware is available. Some proqrams
are exceptionally powerful, versatile, and convenient, while others have
rather stringent limitations which must be considered before purchase. The
most important limitations in database applications are size, arithmetic
operations, and access re lationa 1 operations I .
Size limi tations may be imposed bv the machi ne, hut not always directlv
by the size of random-access memorv. For example, while manv machines feature
the ability to expand RAN capacity by installing additional memorv boarRs,
many database proqrams are limited to the RAN available on the basic svs tern
f or which they are des iqned . Thus, the ef f ective capaci tv of the database
-25-
PURCHASE
ORDER NO : f 18DATE: [ WOLVERINE BOATYARDS
ANN ARBOR, MICHIGANMATERIAL REQUISITION
AND
DATABASE ENTRY FORM
PART NO. : <I2
PART DESCRIPTION : "l3
VENDOR
ADDRESS * 5
CITY, STATE, ZIP: * 6TELEPHONE * 7
/NUMBER OF UNITS .> 34
/
VENDOR CODE NUMBER : *2COST PER UNIT : . 33
TOTAL PURCHASE PRICE : > 35
4 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 0 0 ~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 4 ~ ~ ~ ~ ~ ~ ~ ~ ~ 0 ~
FIGURE 7
Typical database input screen � This screen will prompt the user to fill inthe information to be stored and used with the database. Each entry promptsthe user for the pertinent information with a descriptor, such as vendor:.Following the descriptor is a field indicator. Example field indicatorsare: *-alphanumeric,[-must fill date filed, .-decimal field, and >-must filldate field. These field indicators insure the information is of the correcttype to insure record compatability. Following the field indicator is thenumber of the field the information will be stored. / indicates the end ofthe field. Any information which exceeds the / will be lost.
WOLVERINE BOATYARDS
ANN ARBOR, MICHIGANDATE : [
DATABASE OUTPUT SCREEN
PRODUCTION "ONTROL SAMPLE
/ DEPARTMENT : * 13/ WORK CELL : * 14
COST CONTROL NO. : *12WORK PACKA"E NO. : +16
CUMULATIVE VARIANC: kI 29 CUMULATIVE VARIANCE: . 30
/ TO [FOR THE PERIOD [
~ ~ ~ ~ ~t
~ ~ ~ ~ tt eo l I ~ ~ ~ 1a ~ o ~ s f ~t
~, l,~ ~~ ~ 92 ~
FIGURE 8
Database Output Screen � Production control reports can be quickly and efficientlyproduced with the database systems currently available. The information can bepresented in any format desired by the user. Similar to FIGURE 7, the data isformatted with a descriptor, a field indicator, field number, and end of recordindicator. Note that not all of the information vill be supplied by the database,the user must still fill in the date and period of the report. However, the programmay fill in dates automatically with the computers internal clock.
25b
SCHEDULE % COMPLETE : fi 20ACTUAL % COMPLETE . i' 21VARIANCE f/ 22SCHEDULE INDEX: f/ 23
/% BUDGETED COST/% ACTUAL COST/ VARIANCE/ COST INDEX
$. 2425
26
27
may be software-limited, rather than hardware-limited.
Sof tware capacity limitations mav results from the following
considerations:
� ! Maximum number of files def inable within a Ratabase.
�! Maximum number of records within each file, and within the datahaseas a whole.
3! Maximum number of different fields per record .
�! Maximum total number of characters per record .
Each of these quantities qenerallv has an absolute limit, hut all of
these limits may not actually he achievable simultaneously. For example, in
increasinq the amount of information stored in each record, the user generallv
decreases the total number of records available.
In many cases, too, the limits cannot, be exceeded without causinq the
system to "stall," or even "crash." In stallinq, a filleR database will lock
out all new entries, and may even prohibit modifications to existing entries.
Although none of the existing database information is lost, the operator mav
waste some time and effort enterinq Rata into the input and Risplav buffer,
only to find that this information cannot be transferred into database memory
due to the filled condition.
In more unfortunate cases, a filled system may start to overwrite itself,
losinq previously stored data. Needless to sav, it cannot be assumed that the
data lost is the oldest data, and therefore no lonaer useful. Similarlv, the
overwritinq may occur into a file space containing clifferentlv formatteR data,
which will cause further errors when data is to be recovered from that file.
Needless to say, any qood database svstem should stop dead before it does
this much damage.
F!owever, most serious problems ran he averted hy ensuring that the
system generates some kind of message as the capacity limit is approached, or
at least that the operator has some convenient means of. Retermininq how much
usable space remains in the database. Old records must he trans f erred to
separate inactive or "dead-files" storaqe, to make room for new entries. To
avoid system interruptions due to database fi llup, this file-saving operation
should be done on a fairly reqular basis, rather than wai ting until thinqs
ge t tight.
The ari thmetic operations available in di f f erent systems vary wide lv.
The potential database buyer must carefully consider which arithmetic
operations he will use, takinq account insofar as possible of future needs and
applications. For example, the user may beqin with an application of the
database program in the business of f ice alone, hut he should consider whether
database concepts will eventually he used hy engineerinq or production, which
may well have more complicated arithmetic and statistical needs.
The most signif icant potential problem in microcomputer databases,
however, is in terms of permitted types of access to the Rata. Some database
management proqrams are truly relational across all files in the database, and
can move from file to file with ease while carryinq out relational operations.
Access can he specifieR throuqh any attribute, or combination of attrihutes,
in any file. Less sophisticated proqrams, however, may only allow relational
access throuqh a sinqle master file in each database. All other files in
the database can be accessed only by direct record location, based on searches
throuqh the master filch This limitation implies that the hurRen is on the
user to ensure that the database is set up to allow Rata in the support files
to be accessed by cross-referencinq from the master file.
The next. section, codinq systems, is stronql v related to the concept
of the dat.abase. In the desiqn of his codinq system, the system user
obviously imposes certain field width and storaqe-capacity limi tations on his
own database. At the same time, however, he can ensure that database entries
are fairly standard, easy to enter and correct, transparent and logical, and
convenient to use as keys in searching for particular records.
CODING SYSTFHS
The use of a special "lanquaqe" is essential in the application of the
microcomputer in the boatyard. The shipbuildinq industry has, of course,
developed its own terminology based on traditional usaqe. bulkhead, deck,
floor, even the words port and starboard, are terms which would be clearly
understood by builders, althouqh not by many other people, and still less by a
computer, at the outset. In order to keep track of inventory, tor example, or
to follow the progress of a particular part or assembly throuqh the yard, the
computer must be provided with a descriptive "language" that is concise,
easily entered, and capable of manipulation by the machine. For other
reasons, of course, the words of this "lanquaqe" should be easi lv inter preteR
by people, too. What is required is a compact, standardized set of. svmbols
that can be used to pass information reqardinq the various items that the yard
must work with, or the various qr oups or functions within the yard or the
entire company. This set of. symbols may be referred to as a code.
For reasons of storaqe efficiency, the computer is served best either by
a purely numerical languaqe, or by by short sequences of letters and numbers,
alphanumeric strinqs, as they are called. The advantage of usinq some
alphabetic characters in the code is that if the letters are chosen
meaningfully, they will assist the user in enterinq, interpretinq, and
cor rec ting the data. The machine itself, of course, is indi f f e rent to the
actual appearance of the code, but onl v requires that the set of codes be used
consistently.!
Prior to developinq the code it is most important to consider who will be
using the information in the code, and what functions the information will
have to the operator, the user, and within the proqram itself. The record
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cataloging process described in an earlier section is a good model for
evaluating the kinds of information that may be required in the code.
Another aid to this process is shown in Fig. 9. Each component of the
information contained in a code requires a "field," that is, a series of
consecutive columns reserved to receive a particular number of characters.
The fields can be separated by dashes, by blank spaces, or they can be
adjacent although this can make the code more difficult to enter or read! .
Depending on the amount of information to be contained in a particular code,
therefore, the total length of the code may vary from one character to an
entire line, or morc' Naturally, very long codes are less efficient from
both the machine-storage and human-convenience standpoints, and in general
enough information for most purposes can be conveyed in a code of reasonable
length.!
There are a number of different approaches to coding systems in use. In
the manufacturing environment, two primary forms of codes are most commonly
used in database systems, namely, "hierarchical" and "indexed.'
A hierarchical code is a tree-like structure, in which each item of
information must be present in a strict order. For example, the first field
in the code may represent a particular item of output, while the second field
may be a description of a particular attribute of this item . This second
field might have another meaning depending on the contents of the first field .
In general, the chain of reference in a hierarchical code goes from right to
right.
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-3oa-
0'0 0G
a4
0
4 8C40
4
S
cC
c5U
4
U I I
G
Q
8
'U 0
6'e CI
CI
'4
S 8C
Q
8 Q
R R
By contrast, an indexeR code sometimes called a referencinq code!
implies only a location within a specif ied list of items. In ef feet, the code
is analoqous to a conventional filinq svstem, althouqh it does not have to
have an obvious order. This concept is illustrated in Fiq. 10. As in an
alphabetically ordered file, the fact that two Rif ferent codes may beqin with
the same character has no particular relationship to any similaritv between
the meani nqs of the two codes, any more than pi pi nq, pane llinq, or plate are
similar because the words all beqin with the letter "p." Althouqh there are
applications for indexed codes in many areas, most database manaqement
proqrams are best used in conjunction with a hierarchical system of codes.
One of the considerations that Ristinquishes a "qood" codinq system from
a "bad" one is the degree to which the code can aid in correctinq mistakes in
input, or in avoiding mistakes in interpretation. Codes can be given some
error-resi stinq qualities either bv addinq redundant characters to each field,
or hy addinq characters that are transparent to Fnqlish. For example, to
represent, the three-field code 00-12-37, an entry miqht be made in the form
0000-1122-3377. Thus, any appearance of dissimilar Riqits in the first two or
last two columns of each expanded field would be recoqnized hy the machine or
by the operator! as an error. However, it is obvious that this a cumbersome
arranqement.
Addinq mnemonic alphabetical prefixes to fields is a common plov. In
order to aid in error recovery, two quidelines should be followed: first, the
mnemonic should contain enough letters to mean somethinq obvious> second, the
meaning should tend to persist even with one character missinq or incorrect.
Finally, in developinq a code, the followinq qeneral rules may be of some
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FIGURE 10 a. Hierarchical Structured Cade � 3 implies 4, 4 implies A.
FIGURE 10 b. Referencing Code-- no relation between similar code words.
FIGURE 10 c. Networked Hierarchical Code-- If B. then A.3 and B.l, B.2, and C.
A! !.3.3
B ,2.1B ~ p .2.2B<p.2 3
FIGURE 10 d. Combinatian of Referenced and Hierarchical Coding.
1 ! The code should consist of a series of fields, separateR bv hyphens
for clari ty.
2! In general, each field should correspond to information that is useRby a particular department or function within the varR. In this wav, reportsgenerated from the database using the codes can be easilv tailored to give thevarious departments only the information they need from a particular code,nothing more and nothing less.
�! Do not include information items that can be directlv derived fromother fields in the code. This tvpe of redundancv does not contribute vervmuch to error recovery, and it hoes use up both input time and storage snace.
4 ! Use alphanumeric codes . Meaningful pre f ixes will aiR in readahi litvand in error recovery. The cost in computer storage is negligible, becausethe "internal" form of the code doesn' t have to 'have the same appearance as
the external representation.
�! Keep the code as short as possible, consistent with expressing allthe necessary information. The longer the code becomes, the more chance thereis for an error.
�! Do not include information in the code that has no immediate user.However, leave room for future additions in the database for expansion. Thismeans that you may want to incorporate extra fields in the definition of arecord. They can be lef t empty until they are needeR. On the. other hand, iffuture needs dictate the inclusion of additional information and there is no
room lef t in the record description, the entire system of Rata storage mavhave to be overhauled.
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