module
16
MOS 1.21 is MOS 1.2 with three edits. Everything from 0F4Bh onwards is 13 bytes (0Dh) higher in 1.21, and every address pointing there - in JP, CALL, LD, and the entries of FMTBL - is 0Dh larger to match. S13 tells the story; this is the full list.
| MOS 1.2 | MOS 1.21 | 1.2 | 1.21 |
|---|---|---|---|
| 009Ch | 009Ch | LD A,27h (second write to port 11h at start-up) | LD A,15h |
| 0146h-0147h, 015Ch, 0166h | 0146h, 015Bh, 0165h-0166h | MOS 1.2 | MOS 1.21 (banner and message) |
| 0F4Bh-0F4Dh | 0F4Bh-0F50h | RRA / JR NC,0F49h | AND 05h / CP 05h / JR NZ,0F49h |
| - | 0F55h-0F58h | - | LD A,35h / OUT (11h),A |
| - | 0F61h-0F66h | - | PUSH AF / LD A,05h / OUT (11h),A / POP AF |
| 1FD2h-1FFFh | 1FDFh-1FFFh | 46 unused bytes | 33 unused bytes |
The routine at 0F48h is call 160; the second and third insertions are in call 161's routine, which starts at 0F52h in 1.2 and 0F55h in 1.21.
| Call | 1.2 | 1.21 |
|---|---|---|
| 154 | 015Dh | 015Ch |
| 159 | 0F5Ch | 0F69h |
| 161 | 0F52h | 0F55h |
| 162 | 1CEBh | 1CF8h |
| 163 | 1CEEh | 1CFBh |
| 174 | 1E1Bh | 1E28h |
| 175 | 1DDCh | 1DE9h |
| 180 | 0F6Ah | 0F77h |
| 182-187 | 1E8Dh, 1EA2h, 1EA7h, 1EACh, 1EB1h, 1ECDh | each + 0Dh |
| 188 | 0FAEh | 0FBBh |
| 189 | 1E72h | 1E7Fh |
| 192 | 0F92h | 0F9Fh |
| 196-205 | 1893h ... 19B6h | each + 0Dh |
Entry 154 moves down one byte with the version text; entry 161 moves by three because its routine starts after the first insertion. Every other call keeps its routine's address.
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