Hallo allemaal, I just found the GEOS cartridge I mentioned a week or so ago. It has 'only' five parts: - a switch between EXROM and GND to en/disable the cart - two 27C256 EPROMs - one unknown 14 pins IC - one unknown 16 pins IC Unfortunately the codes of the two ICs have been removed :( But I'm quite sure that the 16 pins one is a 74175. The problem: my IC tester says it's not. But I just had the idea to test this by replacing it with a marked one. (not now, tomorrow) The 14 pins one gives me head aches: +------+ +----- 2 -+ | +------+ PHI2 -----+ | ?? +- 1 ---- 5 -+ | +----- 3 -+ | | ?? +- 4 --- 9 of 175 +------+ +-- 6 -+ | | +------+ IO1 -----------------------------+ Pins 8..13 are not used. There aren't many ICs with outputs at pin 1 and 4. What immediately came to my mind was the 7402. But pin 9 of the 175 has a rising edge. OTOH, at the falling edge of IO1 the address should be valid as well and that could work. But again the same problem: my IC tester says it's not. We'll see tomorrow. But it could be that one of you know of ICs that I don't know and still fit the description. -- Kind regards / Met vriendelijke groet, Ruud Baltissen www.Baltissen.org Message was sent through the cbm-hackers mailing listReceived on 2013-06-16 21:00:03
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