PCjs Machines

Nine Princes in Amber (1985)

On initial startup (or reset) of the machine below, a PCjs machine script will automatically load “Nine Princes in Amber” disks A and B into floppy drives A: and B: and then start the game.

Preservation Notes

The A and B diskettes are from my private collection, but shortly after purchasing the game in 1985, I modified their contents. For starters, I had patched AMB.EXE on disk A to circumvent its copy-protection:

push    cx
push    ds
xor     dx, dx
mov     ds, dx
mov     ah, 0
pushf                       ; patched with NOP
call    dword ptr ds:4Ch    ; patched with NOP, NOP, NOP, NOP
mov     ax, 401h
mov     cx, 0Ah
pushf                       ; patched with CLC
call    dword ptr ds:4Ch    ; patched with NOP, NOP, NOP, NOP
pop     ds
pop     cx

The copy-protection check was fairly simple: in addition to the usual sectors 1-9 on the first track of disk A, it expected a sector 10 as well, and to obfuscate the sector request, it used a PUSHF, CALL DWORD PTR DS:[004Ch] instruction sequence instead of INT 13h. In addition to the patch, it appears I also reformatted the diskettes and rearranged some of the files, so the original contents of the diskettes, as well as the contents of sector 10, are unknown.

I was able to restore AMB.EXE to its unpatched state, and I’ve included a fake sector 10 on the first track of disk A, so the copy-protection check runs and passes. However, it’s still possible that the disk contents may not be quite right, so if you run into problems, try running the game from a hard disk.

Need hints? You’re in luck, because I also saved the notes I made while playing the game back 1985/1986.

Online References

I also scanned all the printed materials that came with the game and uploaded the PDF to the Internet Archive.

Copy-Protection Information (Disk A)

MFM Sector
Sector ID:010
Track ID:000 - Side ID:000
Size:00128 (ID:0x00)
DataMark:0xFB
Head CRC:0xAC0C (Ok)
Data CRC:0x2BF6 (Ok)

0000| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0008| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0010| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0018| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0020| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0028| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0030| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0038| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0040| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0048| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0050| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0058| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0060| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0068| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0070| F6 F6 F6 F6 F6 F6 F6 F6 | ........
0078| F6 F6 F6 F6 F6 F6 F6 F6 | ........