diff options
Diffstat (limited to 'src/mame/machine/taitocchip.cpp')
-rw-r--r-- | src/mame/machine/taitocchip.cpp | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/src/mame/machine/taitocchip.cpp b/src/mame/machine/taitocchip.cpp index be743a6cfff..dfd85aa29fa 100644 --- a/src/mame/machine/taitocchip.cpp +++ b/src/mame/machine/taitocchip.cpp @@ -64,18 +64,18 @@ CLK is supplied with a 12MHZ oscillator on operation wolf (move below MODE notes to upd7811.cpp?) The four Mode0/Mode1 combinations are: - LOW/LOW 78c11 mem map is 4k external rom (i.e. the eprom inside the c-chip) from 0x0000-0x0FFF; - the low 4 bits of port F are used, to provide the high 4 address bits. - speculation: likely the eprom can be banked so the low or high half is visible here, - or possibly one fixed window and 3 variable windows, managed by the asic? - LOW/HIGH 78c11 mem map boots to internal rom (mask rom inside the 78c11 inside the c-chip) from - 0x0000-0x0fff but the memory map is under full mcu control and can select any of the - four modes (internal only, 4k external, 16k external, 64k external) + LOW/LOW 78c11 mem map is 4k external rom (i.e. the eprom inside the c-chip) from 0x0000-0x0FFF; + the low 4 bits of port F are used, to provide the high 4 address bits. + speculation: likely the eprom can be banked so the low or high half is visible here, + or possibly one fixed window and 3 variable windows, managed by the asic? + LOW/HIGH 78c11 mem map boots to internal rom (mask rom inside the 78c11 inside the c-chip) from + 0x0000-0x0fff but the memory map is under full mcu control and can select any of the + four modes (internal only, 4k external, 16k external, 64k external) The following two modes are unusable on the c-chip: - HIGH/LOW 78c11 mem map is 16k external rom from 0x0000-0x3FFF; - the low 6 bits of port F are used, to provide the high 6 address bits. - HIGH/HIGH 78c11 mem map is 64k external rom from 0x0000-0xFFFF; - all 8 bits of port F are used to provide the high 8 address bits. + HIGH/LOW 78c11 mem map is 16k external rom from 0x0000-0x3FFF; + the low 6 bits of port F are used, to provide the high 6 address bits. + HIGH/HIGH 78c11 mem map is 64k external rom from 0x0000-0xFFFF; + all 8 bits of port F are used to provide the high 8 address bits. VPP is only used for programming the 27c64, do not tie it to 18v or you will probably overwrite the 27c64 with garbage. (see http://www.cpcwiki.eu/index.php/UPD7810/uPD7811 ) |