Hi I'm thinking about making a home made multi cartridge for VIC 20. (Yes, I know that there are quite a few already but making the hardware is a hobby for me). For games it seems rather simple. Some are 4k at A000, some are 8k at A000, some are bigger with 8k at A000 and more at either 2000 or 6000. And there's the Scott Adams adventure games at 6000 too. Even though there are different combinations, no single game cart requires or can even make any use of any other cartridge (except perhaps in theory 40/80 column cartridges together with an adventure game). So here it's just a case of mapping one set of rom images to the correct BLK outputs. But for all other kinds of cartridges there are multiple possible configurations. The most obvious is to have switchable ram at all possible places (including the two I/O blocks) in the memory map. But then there is all kinds of ROM cartridges that might actually be useful to combine. For example Super Expander (the ROM part), Programmer's Aid, VIC-MON, Basic 4.0, firmware for different hardware (IEEE, 40/80 column cards) e.t.c. (And VIC-MON comes in different varieties for usage at different places in memory, although AFAIK it's only the 6000 version that were officially sold, all others are relocations of that). Also there are more than one monitor to choose from (VIC-MON, HES-MON and maybe a few others). Which combinations is of any use? I'm thinking about a design whith four software writable registers for freely selecting rom images for 6000, 7000, A000, B000 and some hardware to reuse one of the registers for 2000 (for games) and perhaps also reuse one of the registers for 4000 (for a relocated monitor). Or should I go all the way with registers for each 4k block 2/3/4/5/6/7/A/B000 and for each 1k I/O block? Combined with on/off for ROM and RAM for each 4k block would probably make it possible to have any desireable configuration. I already have a few EPROM:s large enough to contain most images that I might want, and I also have a few 62256 32k SRAM chips, and some 6264 8k SRAM chips. I also have a few 28256 EEPROM:s, so maybe I'll add both eprom and eeprom to be able to have the already known images in eprom and homebrew stuff in eeprom. Or am I just feature creeping it so it might never be buildt? Perhaps I should go for a few dip switches to enable/disable rom/ram for each BLK and use one EPROM for all stand-alone 4k A000 cartridges (i.e. mostly games) and one EPROM for everything else with combined images containing Super Expander, Programmers Aid, VIC-MON e.t.c.? -- (\_/) Copy the bunny to your mails to help (O.o) him achieve world domination. (> <) Come join the dark side. /_|_\ We have cookies. Message was sent through the cbm-hackers mailing listReceived on 2017-07-18 08:00:03
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