Digital Logic Sim Computer

8-bit processor implemented in a Digital Logic Simulator.
Full documentation: Documentation.pdf

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Demo

Program to calculate Fibonacci of 7 shown in GIF:

00: LDI 1     (513)
01: STA 244   (1012)
02: LDI 1     (513)
03: STA 245   (1013)
04: LDI 2     (514)
05: STA 247   (1015)
06: LDA 244   (500)
07: ADD 245   (2293)
08: STA 246   (1014)
09: LDA 245   (501)
10: STA 244   (1012)
11: LDA 246   (502)
12: STA 245   (1013)
13: LDA 247   (503)
14: ADI 1     (2305)
15: NOP 6     (6)
16: CMP 15    (1807)
17: STA 247   (1015)
18: JGT 20    (1556)
19: JMP 6     (1030)
20: LDA 245   (501)

Instruction Set

Mnemonic	Opcode	Details
NOP	0	No Operation
LDA	1	Load RAM -> ACC
LDI	2	Load Immediate -> ACC
STA	3	Store ACC -> RAM
JMP	4	Jump Unconditionaly
JEQ	5	Jump if E FLAG
JGT	6	Jump if G FLAG
CMP	7	Set FLAG
ADD	8	Add ACC += RAM
ADI	9	Add ACC += Immediate
SUB	10	Add ACC -= RAM
SBI	11	Add ACC -= Immediate
SHF	12	Shift ACC <<= RAM
AND	13	And ACC &= RAM
ORR	14	Or ACC |= RAM
XOR	15	Xor ACC ^= RAM

Python Helper

Helper script to convert from the Assembly-like language to the decimal ROM codes Example Program:

LDA 200
ADI 1  
STA 200

Example Output program.txt

456
2305
968

Files

Chips/               # Logic chips
Documentation.pdf    # CPU design & instructions
Operation2Decimal.py # Python helper script
program.txt          # Example program

Running

Make sure you have Digital Logic Sim installed

Create a new project or add to a previous project and get its location e.g.

%APPDATA%\SebastianLague\Digital-Logic-Sim\Projects\MyProject\

Copy all files in Chips/ folder into the appdata Chips/ folder

After scripting your program using the python helper, copy the decimal codes in program.txt and paste it in the ROM chip inside the sim

now open the CPU core and press Enable!

Credits

Inspired by Sebastian Lague’s Digital Logic Sim