On 10/08/2013 07:03 PM, Gerrit Heitsch wrote: > On 10/08/2013 06:31 PM, Ruud@Baltissen.org wrote: >> Hallo allemaal, >> >> >> I designed and built a 6530 replacement, please see: >> >> http://www.baltissen.org/newhtm/6530repl.htm >> >> The problem: it doesn't work :( I get five blinks on my 8250LP, >> meaning: error zero page RAM 6530. Please have a look at the >> schematic and maybe you can see if I am overlooking something. Many >> thanks! > > > Unless I'm reading the datasheet for the 6530 wrong, you also need _RSO > to select the RAM which will cover some parts of the ROM: > > From the datasheet: > > A 64 x 8 static RAM is contained in the MCS6530. It is addressed by > A0-A5 (Byte select), RS0, A6, A7, A8, A9 and, depending on on the number > of chips in the system, CS1 and CS2. > > To me that reads that the RAM will cover parts of the ROM, the location > depending on a mask programmed matrix. You will then also need to use > _RS0 in your circuit to select the RAM part of the 6532. > > Also.. How is RS0 generated on the PCB? Your circuit assumes that as > soon as RS0 goes LOW, you can enable the ROM. Is that correct or will > RS0 go LOW at other times with the CS-Lines inactive then? Ok... Forget that part with RAM, I did misread the data sheet, but while the datasheet is unclear in some respects, to me it looks like you need to have RS0 = HIGH to read the ROM and LOW for RAM and I/O. Your circuit has that inverted. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2013-10-08 18:02:10
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