Im looking for some help. I have a MR-X sound card. The GAL chip on it got very warm and it no longer works.
As there are only two ICs - GAL and AY sound chip it should be an easy fix, except I cant source the GALs.
Is there anyone who could program a GAL for me? I'll be happy to pay for the GAL, any post and packing costs and even buy a beer*.
* Other drinks are available
I'm actually in the process of designing my own ZON x-81 compatible PSG for my ZX81+35 clone, and it has been a puzzle to find out details, like clock frequency, and I/O addresses, and such things, the (preliminary) result of my efforts (schematic) can be found here: https://revspace.nl/ZX81%2B34_ZX81_clon ... sion_board
I knew about the mr-x soundcard and have been curious about further details, but just as details about other PSG systems for the ZX81 they are hard to get and some sources are contradictory.
For example, does the son x-81 use 1.625MHz, or something like 100KHz as a clock?
I want to create a zon x-81 clone where you can also read from the PSG registers, would that be possible?
I got a Mail from Rich and a PN from SirMorris. I will send him the JED files this weekend. He'll burn the GAL and ship it to you rune.
I will soon offer on my homepage those files, so that everybody can use them. Anyway they are public domain and for free .....
1.625 is the sound chip frequency I use when setting Sergey Bulba's AY emulator to Zonx-81 mode and it sounds just right, if that helps.mahjongg wrote:
...For example, does the son x-81 use 1.625MHz, or something like 100KHz as a clock?