Please use google translator to read text because site is in polish language.
You need Pc-speed software available on Atarimania site and MS-DOS boot disk. I tested emulator and it work under MS-DOS 6.22 well.
tOri wrote: ↑Fri Jan 28, 2022 11:09 pm
-> joska - try to fix your device and write about success or fail, thanx.
Thank you so much for this! Yes, I will now attempt to get my PC-Speed working Need to finish a couple of other projects first simply to clear some space on my workdesk.
That was quick I just replaced the GALs, did not do any other repairs or checks. Before this pc_speed.prg would not detect the presence of PC Speed. Now I just have to find my DOS boot-disk and see if the emulator actually works...
2022-01-29 14.29.06.jpg
This is in an otherwise stock Mega 2. No harddisks connected (yet).
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It was really quick I'm sure it is working good because you see pc-speed boot screen.
I'm curious about old GALs operationality. Maybe they simply are deprogrammed by time?
You can check it using programmer.
I have to warn everyone who uses devices with old CPLDs like the GAL or memories like EPROM, EEPROM. It looks like they might come lost single configuration bits due to aging and for some other reason. Datasheets mentions about 20-30 years of data retention. Only way to keep these working for next years is to reverse engineer all logic inside secured chips and reprogram they like new. Don't be surprised when your beloved device stop working someday due to single bitflip... I ask everyone who can help with it and can contribute old devices for reverse engineering before they'll completely die...Not all will be rebuilt because some devices are secured by custom chips, but some can be...
It will be a serious problem for all vintage computing...
joska wrote: ↑Sat Jan 29, 2022 2:55 pm
Have not checked the old GALs yet, will do it later this weekend.
Both the old GALs could be programmed and successfully read back, but when I reinstall them my PC-Speed does not work. So there's something fishy with atleast one of them. I will not spend any more time on this as it works perfectly with the new GALs.
Last edited by joska on Sun Jan 30, 2022 12:39 pm, edited 1 time in total.
Really - it looks strange and is not obvious. Not all pins are involved in the programming process of GAL. I suspect that one of the outputs is damaged.
