mith College

Computer Science

Dominique Thiébaut dthiebaut@smith.edu

CSC270 Spring 2016Circuits and Systems

Lecture Notes — Week 8

D. Thiebaut, Computer Science, Smith College

Goal

D. Thiebaut, Computer Science, Smith College

Goal

D. Thiebaut, Computer Science, Smith College

Goal

D. Thiebaut, Computer Science, Smith College

Goal

D. Thiebaut, Computer Science, Smith College

The Motorola 6811 Processor

• M68HC11 CPU • 8 Kbytes ROM • 512 Bytes of On-Chip EEPROM • 256 Bytes of On-Chip RAM • 8-Channel, 8-Bit Analog-to-Digital (A/D) Converter • 38 General-Purpose Input/Output (I/O) Pins

D. Thiebaut, Computer Science, Smith College

The Motorola 6811 Processor

• M68HC11 CPU • 8 Kbytes ROM • 512 Bytes of On-Chip EEPROM • 256 Bytes of On-Chip RAM • 8-Channel, 8-Bit Analog-to-Digital (A/D) Converter • 38 General-Purpose Input/Output (I/O) PinsSystem On a Chip

(SOC)

D. Thiebaut, Computer Science, Smith College

The Programmer's View of the 6811

D. Thiebaut, Computer Science, Smith College

Simplified Architecture

D. Thiebaut, Computer Science, Smith College

Programmer's View

D. Thiebaut, Computer Science, Smith College

Complete Architecture

D. Thiebaut, Computer Science, Smith College

A Sample of 6800 Instructions

http://www.science.smith.edu/dftwiki/images/9/9e/CSC270_Assembly_Instructions.pdf

D. Thiebaut, Computer Science, Smith College

LDAALDAA 0A ; AccA <— Mem[A] (direct)LDAA 0100 ; AccA <— Mem[100](extended)LDAA #3 ; AccA <— 3 (immediate)LDAA X,4 ; AccA <— Mem[X+4](indexed)

LDABLDAB F0 ; AccB <— Mem[F0] (direct)LDAB 0200 ; AccB <— Mem[200](extended)LDAB #3 ; AccB <— 3 (immediate)LDAB X,4 ; AccB <— Mem[X+4](indexed)

LDXLDX #0010 ; X <- 0010 (immediate)

D. Thiebaut, Computer Science, Smith College

STAA

STAA 00 ; Mem[0] <— AccA (direct)STAA 0000 ; Mem[0] <— AccA(extended)

STAB

STAB 00 ; Mem[0] <— AccB (direct)STAB 0000 ; Mem[0] <— AccB(extended)

D. Thiebaut, Computer Science, Smith College

ADDA

ADDA 00 ; AccA <— AccA + Mem[0](direct)ADDA 0000 ; AccA <— AccA + Mem[0](extended)ADDA #3 ; AccA <— AccA + 3 (immediate)

ADDB

ADDB 00 ; AccB <— AccB + Mem[0](direct)ADDB 0000 ; AccB <— AccB + Mem[0](extended)ADDB #3 ; AccB <— AccB + 3 (immediate)

ABA

ABA ; AccA <— AccA + AccB (inherent)

D. Thiebaut, Computer Science, Smith College

INCAINCA ; AccA <— AccA + 1 (inherent)

INCINC 0003 ; Mem[03] <— Mem[03]+1 (extended)

INCBINCB ; AccB <— AccB + 1 (inherent)

D. Thiebaut, Computer Science, Smith College

JMP

JMP label ; PC <— label (extended)

D. Thiebaut, Computer Science, Smith College

First 6800-Assembly Program

D. Thiebaut, Computer Science, Smith College

void main() { char a=2, b=3, result=0; result = a + b; }

ORG 0000a DB 3b DB 4result DB ? ORG 0010start: LDAA a ADDA b STAA result JMP start

D. Thiebaut, Computer Science, Smith College

Assembling By Hand

http://www.ele.uri.edu/Courses/ele205/6811-Instructions/index.html

ORG 0000a DB 3b DB 4result DB ?

ORG 0010start: LDAA a

ADDA b STAA result JMP start

D. Thiebaut, Computer Science, Smith College

Assembling By Hand

http://www.ele.uri.edu/Courses/ele205/6811-Instructions/index.html

ORG 0000a DB 3b DB 4result DB ?

ORG 0010start: LDAA a

ADDA b STAA result JMP start

What can you say about the different

bytes?

D. Thiebaut, Computer Science, Smith College

We stopped

here last

time…

D. Thiebaut, Computer Science, Smith College

Side Notes• Motorola 6811 instruction set different from the

Pentium instruction set. Different register sets.

• Different architecture but same groups of instructions (data move, arithmetic and logic, control), and similar addressing modes.

• A note about C, C++, Java and Python programs running on different processors.

• Speed of execution C++, vs Java, vs Assembly http://www.science.smith.edu/dftwiki/index.php/Speed_of_Instructions:_Nasm,_Java,_C%2B%2B_and_Python_comparison

D. Thiebaut, Computer Science, Smith College

Assembling By Hand

http://www.ele.uri.edu/Courses/ele205/6811-Instructions/index.html

ORG 0000a DB 3b DB 4result DB ?

ORG 0010start: LDAA a

ADDA b STAA result JMP start

D. Thiebaut, Computer Science, Smith College

Assembling By Hand

http://www.ele.uri.edu/Courses/ele205/6811-Instructions/index.html

ORG 0000a DB 3b DB 4result DB ?

ORG 0010start: LDAA a

ADDA b STAA result JMP start

D. Thiebaut, Computer Science, Smith College

Assembling By Hand

http://www.ele.uri.edu/Courses/ele205/6811-Instructions/index.html

ORG 0000a DB 3b DB 4result DB ?

ORG 0010start: LDAA a

ADDA b STAA result JMP start

D. Thiebaut, Computer Science, Smith College

Assembling with an Assembler

Visit this page before continuing…

D. Thiebaut, Computer Science, Smith College

Assembling with an Assembler

http://www.science.smith.edu/dftwiki/index.php/CSC270_Assembling_6800_Assembly_Programs_on_OSX/Windows

D. Thiebaut, Computer Science, Smith College

www.science.smith.edu/dftwiki/index.php/CSC270_Assembling_6800_Assembly_Programs_on_OSX/Windows

D. Thiebaut, Computer Science, Smith College

www.science.smith.edu/dftwiki/index.php/CSC270_Assembling_6800_Assembly_Programs_on_OSX/Windows

D. Thiebaut, Computer Science, Smith College

www.science.smith.edu/dftwiki/index.php/CSC270_Assembling_6800_Assembly_Programs_on_OSX/Windows

0000 03 0001 04 0002 00 … 0010 96 0011 00 0012 9B 0013 01 0014 97 0015 02 0016 7E 0017 00 0018 10

D. Thiebaut, Computer Science, Smith College

ExerciseWrite and assemble a 6800 assembly program that computesy = 2*x + 3, where x and y are byte variables…

D. Thiebaut, Computer Science, Smith College

Instructions Cycles

http://www.science.smith.edu/dftwiki/images/7/71/6811CycleByCycle.pdfSection 10, Pages 10-6 and 10-13:

D. Thiebaut, Computer Science, Smith College

LDAA 03 ; Acca <— Mem[03] (direct)

D. Thiebaut, Computer Science, Smith College

LDAA 03 ; Acca <— Mem[03] (direct)

D. Thiebaut, Computer Science, Smith College

LDAA 03 ; Acca <— Mem[03] (direct)

D. Thiebaut, Computer Science, Smith College

LDAA 03 ; Acca <— Mem[03] (direct)

D. Thiebaut, Computer Science, Smith College

LDAA 03 ; Acca <— Mem[03] (direct)

D. Thiebaut, Computer Science, Smith College

Example Program ORG 0000

a DB 0

ORG 0010start: INC a JMP start

D. Thiebaut, Computer Science, Smith College

D. Thiebaut, Computer Science, Smith College

D. Thiebaut, Computer Science, Smith College

D. Thiebaut, Computer Science, Smith College

Timing DiagramE

R/W'

Address

Data

D. Thiebaut, Computer Science, Smith College

Observing the Execution with a Scope

D. Thiebaut, Computer Science, Smith College

You are ready forLab 7!