CARDIAC A cardboard illustrative aid to computation

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CARDIACA cardboard illustrative aid to
computation

• illustrates the operation of a computer
• demos basic units of a simple computer
• input
• memory
• accumulator
• program
• output

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Simple Computer Block Diagram
output
input
program unit
memory
accumulator
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SIMCO
Instruction register
Program unit
Program counter
Control unit
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(No Transcript)
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The IR
The function of the instruction register is
to store each instruction word during the
time that particular instruction is being
executed. Once this instruction is executed, the
IR is fed a new (instruction) word.
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CARDIACs IR
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Program Counter (PC)
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CARDIACs PC
Program counter bug
Program counter bug
Noteit has Moved to Next instr
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Flow Chart
Start
receive numbers to be added
do addition
announce answer
stop
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Turn on computer
Start
Take 1st no., from input and store in memory
READ FIRST NUMBER
Take 2nd no., from input and store in memory
READ SECOND NUMBER
clear acc and transfer 1st no. to it from memory
PUT 1ST NUMBER IN ACCUMULATOR
transfer 2nd no. from mem to acc and add it to 1st
ADD SECOND NUMBER TO FIRST
STORE SUM IN MEMORY
transfer sum from acc to memory
transfer sum from mem to output and print
PRINT SUM
Stop
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017 read first number 018 read second
number 117 put first in accumulator 218 add
second to the first 619 store sum in
memory 519 print sum

memory location
computer word
operation code
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MEMORY
00
05
01
addresses
02
03
04
SIMCO has 100 addresses (00 through 99)
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CADIACs memory
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Converting SIMCO to THE Stored-Program Mode
Instruction Register


Program Counter
Program Unit

Control Unit
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input
control
memory
cell selector
cells
output
accumulator
op code
address
instruction register (IR)
program counter
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Program Example
017 read (input) first number 018 read second
number 117 put first number into the
accululator 218 add second number to the
first 619 store sum in memory location
19 519 print the sum
Memory locations
Operation codes(op codes)
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Op codes
cardiac Instruction Set
Op Code Abbr. Meaning ------- ----
----------------------------------- 0 INP
Input. Read from input device 1 CLA
Clear accumulator and add 2 ADD
Add to accumulator 3 TAC Test
accumulator contents 4 SFT Shift
accumulator contents 5 OUT Output.
Write to output device 6 STO Store
accumulator to memory cell 7 SUB
Subtract from accumulator 8 JMP Jump
to address 9 HRS Halt and Reset
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You can install a javaversion of cardiac
Requires Java language be installed first Your
instructor will demonstrate CARDIAC in
operation. http//sourceforge.net/project/showfil
es.php?group_id49761release_id91891 Note to
install type java jcinc from DOS command
window Play around with ittry to figure out how
to write and execute a program
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CARDIAC program
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1st program instruction
Note program begins in memory Location nine
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Data wordsload here
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Output 8 9 17