Hello Ruud, > I designed and built a 6530 replacement, please see: > > http://www.baltissen.org/newhtm/6530repl.htm Ohh, nice. I did it in the year 1990, too. > 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! Okay, what did you do? /CE (Pin 20) and /OE (Pin 22) from EPROM is /RS0 from 6530 CS1 (Pin 38)from 6532 is GND /CS2 (Pin 37) from 6532 is from the logic around 74LS08 and 74LS139. /RS (PIN 36) from 6532 is A6 (Pin 8) A5 A6 /RS0 CS2 /Y0 /Y2 /CS2 Pin 10 Pin 8 Pin 4 Pin 19 Pin 37 0 0 1 0 0 1 0 *) 0 1 1 0 1 0 0 *) 1 x x x 1 1 1 x x 0 x 1 1 1 x x x 1 1 1 1 or *) 0 x 1 0 0 /CS2 = /A5 & /RS0 & /CS2 is that true? Now i look at my schematics: /CE (Pin 20) from EPROM is /RS0 *) (Pin 4) from 6530 (it's the same) /OE (Pin 22) from EPROM is the inverted Phi2 (Pin 3) from 6530 (but this isn't your problem) CS1 (Pin 38) from 6532 is inverted A6 (Pin 8) from 6530 /CS2 (Pin 37) from 6532 is CS2 *) (Pin 19) from 6530 /RS (Pin 36) from 6530 is A7 (Pin 7) and i've an address correction, my A4 (Pin 3) from 6532 is A4 (Pin 11) logical or A7 (Pin 7) from 6530 (if i remember correctly, this is not used by the floppies, but it retranslate the io register from the 6532 to the 6530). So i use only one 74LS02 (three inverter and one nor) for the logic! And this works. I Think you have a problem with some negations! *) I don't know the real invertion from this pins! But this is only the name! Martin Message was sent through the cbm-hackers mailing listReceived on 2013-10-08 23:00:09
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