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Started by gerald, 20:48, 09 October 12
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Quote from: IanS on 19:42, 16 October 12I've just opened my dktronics memory expansion.There is a transistor (BF240) that pulls A15 to +5v. I think that explains it, when the CPU is trying to read &4000-&7FFF, the memory expansion pulls A15 high, which means the reads will actually be from &C000-&FFFF.Seem like quite a hack, but I guess it works.
Quote from: Bryce on 20:06, 16 October 12I also have a 464 and several DKTronics RAM expansions. I can try a few things too when I get time. A question to the other hardware guys here: RAMDIS seems to be connected on the 464 to something although it should technically have no function on a 464, at least not the function found on a 6128. There's a track on the PCB, but it's not mentioned on the schematics (as far as I can see). I think I remember testing it at one time and discovering that it was attached to an address line, but I don't remember which one. So the hardware "trickery" might be on both sides. Have any of you looked at this?Bryce.
Quote from: Bryce on 20:21, 16 October 12My CPC doesn't have an ASIC, I'm talking about a classic 464 here.Bryce.Haven't started on the beer yet, but you've just given me a great idea
QuoteToo much beer already?
Quote from: gerald on 18:34, 16 October 12A15/A14 are cannot exchanged on 464, but the move is physically possible because of way the ROM is connected to the bus.Only A[14:0] are connected to the ROM. The gate array then enable the ROM according to the rom configuration register and A15 state.Seeing the upper ROM at 0x4000-0x7FFF mean that the gate array enable the ROM when A15 is low and upper rom is enabled.The gate array are different on 464 (40007/40008/40010) and 6128 (40010). They behaviour can be different.@arnoldemu : did you test it on a 40007 / 40008 / 40010 or even on cost reduced version ?
Quote from: IanS on 18:19, 16 October 12Can you publish the code that you used to test the &c3 mode.
Quote from: arnoldemu on 09:40, 17 October 12I will later.
Quote from: 00WReX on 23:22, 16 October 12Sorry if this is totally irrelevant but I noticed this the other day when I ran the SyX ramtest program. On a normal 6128 you see this...... On a 664 with DK'Tronics 64K expansion you see this...... Not sure how the program works, but anyway that's what it reports. Cheers,Shane
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