On 6/3/2017 11:15 AM, bwack wrote: > Hi Jim and Mark. I became one of the testers. I accepted to receive and make > a video about it. I didn't know about this discussion at the time, and that > it was a quick mash-up, so this turned more into a pcb 1.0 review than an > easy of use review. > > I've learned that the cartridge sets #EXROM or #GAME, and in some cases both > (16k). Then, why is there a double throw jumper for #EXROM and #GAME? I believe you're trying to use the single ROM cart design for a 16kB cart. I don't think that will work, or at least I never designed it to do so. The design parms for the single EPROM cart was to support putting an 8kB ROM at either ROML or ROMHI had > One chipselect/outputenable, two chipselect signals: > Now the second thing I gather is that the PLA drives #CS and or #OE with > #ROML or #ROMH. Those signals are dependent on #EXROM and #GAME. Because the > overview doc I got from Mindflare says : "Single EPROM support - 2764 or > 27C64 (1 x 8k bank) / 27128 or 27C128 (2 x 8k banks)", I decided to buy an > 27C128. Here is the problem: a double throw jumper has no place on selecting > #ROML and #ROMH for #OE. It's either #ROML or both, right? The second > problem: I have a single chip, but two chipselect/output enable drivers > #ROMH and #ROML. Someone in the thread suggested two diodes and a resistor. > This was not everything needed to make it work. The #ROML was also connected > to A13, the MSB of 27c128's address bus. I don't know. as far as I can tell from the schematic, that cannot happen. Jim Message was sent through the cbm-hackers mailing listReceived on 2017-06-04 00:00:02
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