with function code in AH .
| AH | Description | |----|-------------| | 00h–0Fh | System / reset / configuration | | 10h–17h | Keyboard | | 20h–2Fh | Display (text mode, cursor, scroll) | | 30h–3Fh | Graphics (GDC commands) | | 40h–4Fh | Disk I/O (FDD, HDD) | | 50h–5Fh | Printer / serial | | 60h–6Fh | Timer / date / time | | 70h–7Fh | System information | | 80h–8Fh | Extended memory (EMS / BIOS) | | 90h–9Fh | Sound / beep | | C0h–CFh | Mouse |
AH = 63h CX:DX = microseconds INT 18h (blocks)
One of the most notorious aspects of the PC-98 BIOS for modern users is the CMOS setup utility. On an IBM PC, you press "Del" or "F2" to enter setup. On a PC-98? There was no standard key combination for many models.
If you take an IBM PC formatted floppy and put it in a PC-98, the BIOS will read the first sector, see the signature, but the bootloader will crash instantly because it will try to use IBM BIOS interrupts.
NEC treated the BIOS as proprietary. Many I/O ports used for bank-switching EMS (Expanded Memory) or controlling the 26-pin printer port are undocumented. Emulator authors have to reverse-engineer the BIOS code itself.
AH = 25h AL = lines to scroll CH = top row, CL = left col DH = bottom row, DL = right col BH = fill color INT 18h
with function code in AH .
| AH | Description | |----|-------------| | 00h–0Fh | System / reset / configuration | | 10h–17h | Keyboard | | 20h–2Fh | Display (text mode, cursor, scroll) | | 30h–3Fh | Graphics (GDC commands) | | 40h–4Fh | Disk I/O (FDD, HDD) | | 50h–5Fh | Printer / serial | | 60h–6Fh | Timer / date / time | | 70h–7Fh | System information | | 80h–8Fh | Extended memory (EMS / BIOS) | | 90h–9Fh | Sound / beep | | C0h–CFh | Mouse | pc-98 bios
AH = 63h CX:DX = microseconds INT 18h (blocks) with function code in AH
One of the most notorious aspects of the PC-98 BIOS for modern users is the CMOS setup utility. On an IBM PC, you press "Del" or "F2" to enter setup. On a PC-98? There was no standard key combination for many models. On a PC-98
If you take an IBM PC formatted floppy and put it in a PC-98, the BIOS will read the first sector, see the signature, but the bootloader will crash instantly because it will try to use IBM BIOS interrupts.
NEC treated the BIOS as proprietary. Many I/O ports used for bank-switching EMS (Expanded Memory) or controlling the 26-pin printer port are undocumented. Emulator authors have to reverse-engineer the BIOS code itself.
AH = 25h AL = lines to scroll CH = top row, CL = left col DH = bottom row, DL = right col BH = fill color INT 18h