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+--- Thread: Someone's Fast & Easy Bitmap Graphics (/thread-1087.html)
Someone's Fast & Easy Bitmap Graphics - someone - 09-09-2026
When there's no rules and someone tinkers;
a slight mod of a 128K DRAM Coreboard and Alpha Plus Base board is configured to punch a neat hole in the memory map for easy PCG access.
e.g PCG being accessed at memory location 8000-BFFF or part thereof.
Bank #0 at 8000-87FF
Bank #1 at 8800-8FFF
Bank #2 at 9000-97FF
Bank #3 at 9800-9FFF
Bank #4 at A000-A7FF
Bank #5 at A800-AFFF
Bank #6 at B000-B7FF
Bank #7 at B800-BFFF
Doing this removes the onerous task of tracking & changing PCG banks continually.
A dedicated I/O port is used to augment the existing memory paging scheme to switch in the PCG.
In conjunction with someone's RA3 mod for 8X8 High PCG memory support and enabling Colour RAM, one can perform fast and easy bitmap graphics.
A useful configuration is:
0000-7FFF used for switched DRAM pages
8000-BFFF used for PCG
C000-EFFF used for DRAM (non-switched)
F000-F7FF used for CHAR or ATTR RAM
F800-FFFF used for COLRAM
RE: Someone's Fast & Easy Bitmap Graphics - MbeeTech - 10-09-2026
Excellent thinking Someone.
The 2 new Microbee models have something very similar already implemented, but it allows for PCG banks > 7 as there are 10 banks implemented, 4 planes deep.
Screen, Colour, Attr and font are also mapped in with Linear addressing mode.
RE: Someone's Fast & Easy Bitmap Graphics - Graham72 - 18-09-2026
Noice. But to do this needs a hardware mod? A little easier to emulate tho?
RE: Someone's Fast & Easy Bitmap Graphics - MbeeTech - 13-10-2026
Hi Graham.
Yes, 'Someone's ' Mods do require hardware mods for it to work on a regular Premium series Microbee.
'Someone' may even give us details of the procedure to do the mods at some point ;-)
RE: Someone's Fast & Easy Bitmap Graphics - Graham72 - 13-10-2026
(13-10-2026, 08:02 AM)MbeeTech Wrote: Hi Graham.
Yes, 'Someone's ' Mods do require hardware mods for it to work on a regular Premium series Microbee.
'Someone' may even give us details of the procedure to do the mods at some point ;-)
Thanks, when you have time could you please explain how you see the differences between regular Premium series and the Alpha Plus revisions 1-4?. cheers g
RE: Someone's Fast & Easy Bitmap Graphics - MbeeTech - 13-10-2026
Hi Graham,
The Alpha Plus is the Premium series. Alpha Plus was the name given during development, whereas they were marketed as the Premium Series.
The The first version (Rev 1) included grey scale composite video output circuitry, Rev 2 was not produced as far as I'm aware, Rev 3 dropped the Grey Scale composite
and tidied up ECO's, and Rev 4 was the final production release, again with a few minor changes for production, but nothing significant in terms of functionality.
RE: Someone's Fast & Easy Bitmap Graphics - Graham72 - 13-10-2026
(13-10-2026, 11:42 AM)MbeeTech Wrote: Hi Graham,
The Alpha Plus is the Premium series. Alpha Plus was the name given during development, whereas they were marketed as the Premium Series.
The The first version (Rev 1) included grey scale composite video output circuitry, Rev 2 was not produced as far as I'm aware, Rev 3 dropped the Grey Scale composite
and tidied up ECO's, and Rev 4 was the final production release, again with a few minor changes for production, but nothing significant in terms of functionality.
Thanks Ewan, now Iunderstand. Cheers g