Table of Contents
NEC PC-9801 - I/O Ports
02h
35h
37h
71h
73h
77h
7Ch (GRCG - Control)
7Eh (GRCG - Tile)
NEC PC-9801 - I/O Ports
02h
TODO
35h
TODO
37h
TODO
71h
TODO
73h
TODO
77h
TODO
7Ch (GRCG - Control)
bit 7 - enable (1)/disable (0) GRCG
bit 6 - enable (1)/disable (0) read/modify/write mode
bit 4-5 - select plane exposed to CPU (0-3)
bit 3 - enable (1)/disable (0) plane 3
bit 2 - enable (1)/disable (0) plane 2
bit 1 - enable (1)/disable (0) plane 1
bit 0 - enable (1)/disable (0) plane 0
7Eh (GRCG - Tile)
This port accepts sequential (in order of enabled planes) 8-bit tile data.