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8-bit acorn hardware • Re: Music 500 -> Music 5000 and Music 500 -> Music 3000

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After watching ladies and gentlemen perilously avoiding a nasty bout of E-coli infection, I spent a bit of time figuring out why two different DACs and two different sets of op-amps would give the "wrong" result.

As it turns out the test program that puts a sine wave out, doesn't actually do so.

The shape that comes out isn't a sine wave, it looks as if the sign bit in the M5000 isn't as straightforward as making a memory location negative...

I tried a different technique and went into AMPLE and made a simple test using an enveloped sine wave "Panflute" and yup, perfect sine waves. So the DAC and op-amp is fine. The problem lies somewhere else inside the digital guts of the M5000. I am suspecting the RAM, even though it tests fine in the chip tester, I'm not so confident that it works at the 6MHz cycle time of the M5000.
Playing the same program in AMPLE on BeebEm and M5000

Statistics: Posted by maniacminer — Sat Mar 30, 2024 5:58 pm



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