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+--- Thread: PC85 Menu System Trivia (/thread-295.html)
PC85 Menu System Trivia - someone - 09-03-2021
There are at least two versions of the PC85 menu system known as PC85 and PC85b.
PC85 has its menu code all contained within one ROM at the PAK 5 location.
PC85b however, has its menu code split across two ROMs to accommodate its expansion with the main menu at PAK 5 and the additional support at the PAK 10.
Interestingly, the PC85b also supports 16K PAK ROMs. This is accomplished by using the PAKPORT's D[2:0] select the desired PAK ROM /CS signal (as normal) and additionally D3 to select the upper or lower half (either %0000-%1FFFF or %2000-%3FFF).
For example: PAK 10 is actually the upper half of the 16K PAK 2 ROM.
The PC85 menu system relies upon non-standard and undocumented MWBASIC entry points to accomplish support of the MENU command syntax.
RE: PC85 Menu System Trivia - ChickenMan - 09-03-2021
The PC85b menu is much the same as the Premium PC85 also with 2 16k roms.