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Tidy up formatting

This commit is contained in:
n loewen 2023-07-25 17:41:26 +01:00
parent 9fe17b801f
commit 27a192bcdf
1 changed files with 27 additions and 27 deletions
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readme.md
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@ -8,40 +8,40 @@
- [ ] Consider adding a way to visualize screen memory
- [ ] Do a proper binary version...
## ISA
## Instruction set
0 END
1 STO lit# ; store ... mem[lit#] <- A
2 STO addr ; store ... mem[mem[addr]] <- A
3 LDA lit# ; load ... A <- lit#
4 LDA addr ; load ... A <- mem[addr]
5 ADD lit# ; add ... A <- A + lit# ... and un/set carry flag
6 ADD addr ; add ... A <- A + mem[addr] ... and un/set carry flag
7 SUB lit# ; sub ... A <- A - lit# ... and un/set carry flag
8 SUB addr ; sub ... A <- A - mem[addr] ... and un/set carry flag
9 HOP lit# ; hop ... skip next instruction if A == lit# ... when true: IP <- PC + 2
A HOP addr ; hop ... skip next instruction if A == addr ... when true: IP <- PC + 2
B JMP lit# ; jump ... IP <- lit#
C JMP addr ; jump ... IP <- addr
D CCF ———— ; clear Carry Flag ... CF = 0
E CHP ---- ; carry hop ... skip next instruction if Carry Flag is set ... when true: IP <- PC + 2
F
0 END
1 STO lit# ; store ... mem[lit#] <- A
2 STO addr ; store ... mem[mem[addr]] <- A
3 LDA lit# ; load ... A <- lit#
4 LDA addr ; load ... A <- mem[addr]
5 ADD lit# ; add ... A <- A + lit# ... and un/set carry flag
6 ADD addr ; add ... A <- A + mem[addr] ... and un/set carry flag
7 SUB lit# ; sub ... A <- A - lit# ... and un/set carry flag
8 SUB addr ; sub ... A <- A - mem[addr] ... and un/set carry flag
9 HOP lit# ; skip next instruction if A == lit# ... when true: IP <- PC + 2
A HOP addr ; skip next instruction if A == addr ... when true: IP <- PC + 2
B JMP lit# ; ... IP <- lit#
C JMP addr ; ... IP <- addr
~~D CAT ---- ; Carry Flag Toggle ... CF <- !CF~~
D CCF ———— ; Clear Carry Flag ... CF = 0
E CHP ---- ; skip next instruction if Carry Flag is set ... when true: IP <- PC + 2
F
### Nice features that didn't fit
- hop IF< and hop IF>
- MUL and DIV
- hop `IF<` and hop `IF>`
- `MUL` and `DIV`
- rotates and shifts
## Registers
- A -- accumulator
- IP -- instruction pointer (aka program counter)
- `A` - accumulator
- `IP` - instruction pointer (aka program counter)
## Flags
- CF -- carry flag
- `CF` - carry flag
## Memory-mapped peripherals
@ -55,7 +55,7 @@ F
## Tentative memory map
00-0F - display
10-1F - keypad? (details TBD)
20 - initial value for IP ?
21-FF - free
00-0F - display
10-1F - keypad? (details TBD)
20 - initial value for IP ?
21-FF - free