NEC PC98 CPU devices and I/O ports (Summary)
Reference: PC-9801VX Hardware Manual (1987)
I/O port table
| I/O address | Device(Last bit of address is 0) | Device(Last bit of address is 1) |
| 000 - 007h | Interrupt controller(Master)(8259) | DMA controller(8237) |
| 008 - 00Fh | Interrupt controller(Slave)(8259) | |
| 010 - 01Fh | Reserved | |
| 020 - 02Fh | Calendar/Clock(1990,4990) | DMA bank(8237) |
| 030 - 03Fh | RS-232C interface(8251) | System port(8255) |
| 040 - 04Fh | Printer interface(8255) | Keyboard controller(8251) |
| 050 - 05Fh | NMI | 320KB FDD interface(8255) |
| 060 - 06Fh | GDC(Text)(7220) | Reserved |
| 070 - 07Fh | Screen line/scroll controller(52611) | Timer controller(8253) |
| 080 - 087h | Fixed disk interface | Reserved |
| 088 - 08Fh | Reserved(Sound board(1)) | BRANCH4670 Network board |
| 188 - 18Fh | Sound board(2)(YM2203) | BRANCH4670(mirror) |
| 090 - 097h | 1MB FDD interface(765) | CMT interface(8251) |
| 098 - 09Bh | GP-IB switch | |
| 09C - 09Dh | Reserved | |
| 09E - 09Fh | 68000 board | |
| 0A0 - 0AFh | GDC(Graphics)(7220) | Character ROM |
| 1A0 - 1AFh | EGC Extended address | Reserved |
| 0B0 - 0BFh | Network controller board(7201)/Extended RS-232C board(8251) | |
| 0C0 - 0C7h | ODA printer board(8255) | GP-IB(7210) |
| 0C8 - 0CFh | 640KB FDD interface(765) | |
| 0D0 - 0DFh | Not used | Reserved(※) |
| 7FD0-7FDFh | Not used | ※Mouse interface(8255) |
| 3FDA-3FDBh | Not used | ※Frequency of beep sound(8253) |
| BFD8-BFDBh | Reserved | ※Mouse interrupt polling time |
| BFDC-BFDFh | Not used | |
| 0E0 - 0EBh | Key-down sense | |
| 0EC - 0EDh | Key-down sense | Not used |
| 0EE - 0EFh | Not used | |
| 0F0 - 0F7h | CPU | Not used |
| 0F8 - 0FFh | Numeric data processor | |
| 100 - 3FFh | Mirror of 000 - 0FFh(x3) | |
| 400 - FFFh | Mirror of 000 - 0FFh(External devices only)(x12) | |
| 1000-FFFFh | Mirror of 000 - FFFh(x15) | |
For details, see NEC PC98 I/O ports (Details)
Bellow pictures are photos of CPU and device ICs on NEC PC98.
Intel N80286 - CPU(when the system dip switch SW3-8 is ON)
Intel D82288 - Bus controller for 80286
NEC μPD70116(V30) - CPU(when the system dip switch SW3-8 is OFF)
AMD D8284A - Clocks generator for 8086/8088(V30)
NEC μPB8288 - Bus controller for 8086/8088(V30)
NEC μPD765A - Floppy drive controller(640KB/1MB FDD interface)
NEC μPD4990A - Serial I/O calendar(Real-time clock)
NEC μPD7220A - GDC(Graphic Display Controller)(Text/Graphics controller)
NEC μPD7261A - Hard drive controller
NEC μPD8048 - Microcontroller(Keyboard controller)
NEC μPD8237A - DMA controller
NEC μPD8251AF - Serial I/O(RS-232C interface, Casette magnetic tape(CMT) interface, Keyboard interface)
NEC μPD8253 - Interval timer(Timer controller)
NEC μPD8255A - Parallel I/O(320KB FDD interface, System port, Printer interface)
AMD P8259A - Interrupt controller
Suwa-Seikosha SED9420 - FDD data/clock separator(VFO)
NEC μPD52611 - CRT master slice(Display sctoll/line controller)
NEC μPD65101-S017 - ASIC(EGC(Enhanced Graphic Charger)(VRAM data bit operation accelerator))
PC-9801VX motherboard
