Re: Looking for YMF262

From: Richard Atkinson (
Date: 1999-07-06 13:15:26

On Mon, 5 Jul 1999, Ruud Baltissen wrote:

> I once connected a MGP-card to my C64. The card disappeared during moving from 
> one houde to another. 
> If the sound blaster only uses I/O, one half of a 74LS39 will do the trick. 
> Connect the PHI2-clock with input A and the R/W-line with input B. Output C 
> reflects the needed WR-line, output D the needed RD-line. Connect the IRQ-input 
> thru an invertor with IRQ5 of the card. The only thing I don't have a solution 
> for is the DMA. 
> You must hardwire the addresslines A8 and A9 so that the card sees the range 
> $200-2FF. The AEN-line is connected to PHI2-clock AFTER it has been inverted.

Can you point me to an ISA bus reference? I'm afraid I know nothing about
how it works - whether it's multiplexed or not, what the timing of the
address lines, READ# and WRITE# lines is like, how DMA request and
acknowledge lines work, etc etc etc

> For those interested how I connected the MGP-card which needs RAM-addressing as 
> well: I added a 8255. Two ports I used for A8..A19 and one line I used for 
> telling it was an I/O- or Memory-operation. The other lines I used to read the 
> IRQ-lines of the ISA-slot. These lines were connected to the IRQ-input of the 
> C64 thru a NOR-gate.

I propose that the SoundBlaster 64 interface use non-Plug'n'Play cards
configured for the 'normal' SoundBlaster settings - ie. 220h - 22Fh,
certain IRQs and DMAs.


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