1 Topic by Luzie (edited by Luzie 2023-02-10 12:24:58)

  • Luzie
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Topic: Load a modified 128K ROM and make divMMC work in 128K Editor and Basic

From Facebook-Group "DivMMC and DivIDE interface for ZX Spectrum and Sam Coupe":

Mario Prato:

Hi Guys,
I recently added a new feature into the divmmc cpld, allram mode, it makes possible to map ram into the first 16K instead of speccy rom, this memory may be also write protected to act like a new rom and automatic mapping can be disabled too.
See the videos, now it's possible to load a modified 128K rom from Velesoft and make divmmc work in 128K editor and basic (dot commands are ok). Or we can load a +3e rom for divmmc (in the video I load Workbench +3e).
I know there are lots of different divmmcs and this firmware is only for the ones that follow my original schematic (Ben's for example).
Jedec file is on my github page, source will be avalaible soon: https://github.com/mprato/DivMMC

Videos are in Facebook, and not in Youtube, so I can not post Youtube-Links here.

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2 Reply by aowen

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Re: Load a modified 128K ROM and make divMMC work in 128K Editor and Basic

Should be possible to use DerbyPro that way too.

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3 Reply by velesoft (edited by velesoft 2023-02-23 22:26:26)

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Re: Load a modified 128K ROM and make divMMC work in 128K Editor and Basic

Firmware is in development.
I test current version with more features. Now will be possible boot from SD card own 48 or 128 rom + system (esxdos). Then system may run full in divmmc ram memory without limits and any other system update may be only about rewriting ESXDOS files on SD card (no more eeprom flashing). As bonus can system rewrite own code and also is possible modify own rom image. New CPLD firmware also can install own +3 rom from SD and use it as +3e rom without divmmc system automapper. On Divmmc 128kB and 512kB models may be last 32kB of ram memory used for 128kB rom image and previous 8kB page for system rom data. +3 rom mode support up to 8 different 64kB +3 roms in one Divmmc 512kB memory. And more features...

All this will be possible after finish release by Mario Pratto. All current version of DivMMC interfaces based on original CPLD XC9572XL-VQ64 can be upgraded by update CPLD firmware. But this may be small problem for some users without JTAG programmer. And DivMMC with 512kB memory enable best comfort, because is we load 128 rom and 8kB system to DivMMC with 128kB ram then will be free only 88kB. Esxdos use about 40kB ram, but if we need use LFN browser, then must be used DivMMC 512kB.
DivMMC 128kB is also full usable, but is impossible active all features in same time. For example is impossible use LFN filebrowser by Bob Fosill+own 128 rom + system in ram. But is possible use all features with standard original nmi filebrowser or Dr SLUMP NMI navigator with LFN support. Or not use booting system from SD (boot from original eeprom) in combination with LFN browser(without possibility use own 128rom,etc..)