README formatting

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Izaya 2017-03-13 17:36:11 +11:00
parent 856bcf40f5
commit c5d745608e

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@ -13,23 +13,23 @@ The T400 is an 8-bit stack machine operating at 1Hz (due to ABMs only running on
### Instructions ### Instructions
Any words encountered that aren't instructions are pushed to the stack. This makes very compact simple program code. Any words encountered that aren't instructions are pushed to the stack. This makes very compact simple program code.
| ins | function | mnemonic | | ins | function | mnemonic |
|--------|----------------------------------------------|---------------| |-------|-----------------------------------------------|---------------|
| 255 | push program counter | ppc | | 255 | push program counter | ppc |
| 254 | swap TOS | swp | | 254 | swap TOS | swp |
| 253 | read memory from TOS | read | | 253 | read memory from TOS | read |
| 252 | write to memory from TOS | write | | 252 | write to memory from TOS | write |
| 251 | add TOS | add | | 251 | add TOS | add |
| 250 | suptract TOS | sub | | 250 | suptract TOS | sub |
| 249 | jump to TOS | jmp | | 249 | jump to TOS | jmp |
| 248 | skip if TOS = zero | sez | | 248 | skip if TOS = zero | sez |
| 247 | jump if TOS = zero | jez | | 247 | jump if TOS = zero | jez |
| 246 | jump to subroutine, push pc to retstack | jsr | | 246 | jump to subroutine, push pc to retstack | jsr |
| 245 | return from subroutine, PC = top of retstack | ret | | 245 | return from subroutine, PC = top of retstack | ret |
| 244 | duplicate TOS | dup | | 244 | duplicate TOS | dup |
| 243 | drop TOS | drop | | 243 | drop TOS | drop |
| 242 | halt processor | hlt | | 242 | halt processor | hlt |
| 241 | pre-read address at TOS | prd | | 241 | pre-read address at TOS | prd |
### I/O ### I/O
The T408 uses memory-mapped I/O. This may seem like a stupid idea on a machine with 8-bit addressing but port-based I/O isn't hugely sane. The T408 uses memory-mapped I/O. This may seem like a stupid idea on a machine with 8-bit addressing but port-based I/O isn't hugely sane.