ULA revistited.
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Re: ULA revistited.
Very nice work Andy!
But I have to wonder: why such a big device (package-wise), couldn't find anything smaller to do the job? I'd be thinking about something like Xilinx XC9572XL in 64p TFQP package, the Altera MAX in the pix looks a bit too much (for my taste, at least) in terms of package size & number of I/O pins (and perhaps cost as well)...
But I have to wonder: why such a big device (package-wise), couldn't find anything smaller to do the job? I'd be thinking about something like Xilinx XC9572XL in 64p TFQP package, the Altera MAX in the pix looks a bit too much (for my taste, at least) in terms of package size & number of I/O pins (and perhaps cost as well)...
Re: ULA revistited.
ah well.... they came along at the right price, NOS i was looking for a single chip (5v) instead of the 2 chip mixed voltage offering i played with not so long back.
yeah there are a few io's spare that will give me plenty of tinkering room for the ones in my Zeddies
Regards Andy
yeah there are a few io's spare that will give me plenty of tinkering room for the ones in my Zeddies
Regards Andy
what's that Smell.... smells like fresh flux and solder fumes...
Re: ULA revistited.
I am intrested also...
Mike
Mike
Re: ULA revistited.
That's what I am loving aboute it!!!Andy Rea wrote:yeah there are a few io's spare that will give me plenty of tinkering room for the ones in my Zeddies
It's not just an replacement but gives also plenty of room for enhancements like 512k bankswitched memory, usb-support with v-drive and many many more giving all those select signals needed
Meanwhile our ZX-Team order needs to be increased from 9 to 10.
You are planning a second batch, are you?
In theory, there is no difference between theory and practice. But, in practice, there is.
Re: ULA revistited.
I think i am just about done with the code for the cpld
all previously mentioned mentioned features work in ZX81 mode
Rompatch is not implemented in ZX80 mode.
Turbo works in ZX80 mode
new aux output, Turbo-Active, for connecting LED (must use current limiting resistor) if you wish.
Regards Andy
all previously mentioned mentioned features work in ZX81 mode
Rompatch is not implemented in ZX80 mode.
Turbo works in ZX80 mode
new aux output, Turbo-Active, for connecting LED (must use current limiting resistor) if you wish.
Regards Andy
what's that Smell.... smells like fresh flux and solder fumes...
Re: ULA revistited.
Well there's an interesting thing.....
i have an almost unmodified ZX81 issue 1, with a ROM labeled
I replaced the ROM with one out of another machine labeled
So if your roms not up to speed you may have trouble with clock doubling !
Andy
i have an almost unmodified ZX81 issue 1, with a ROM labeled
When running Turbo mode, it seems like this rom is borderline for access speed as it would sometimes crash but always when running turboSINCLAIR
RESEARCH 8306P7
D2364C 649 (c) 1981
I replaced the ROM with one out of another machine labeled
and the problem has gone away...<motorola symbol>
ZCM38818P
8312
So if your roms not up to speed you may have trouble with clock doubling !
Andy
what's that Smell.... smells like fresh flux and solder fumes...
Re: ULA revistited.
knocked up some instructions....
http://www.debraclayton.webspace.virgin ... ulamk2.pdf
Please if you note any errors let me know and i'll get it changed.
Andy
http://www.debraclayton.webspace.virgin ... ulamk2.pdf
Please if you note any errors let me know and i'll get it changed.
Andy
what's that Smell.... smells like fresh flux and solder fumes...
Re: ULA revistited.
Very good!.. Ii have many ZX81's dead because of the ULA's
is this ready for sale?
Mike
is this ready for sale?
Mike
Re: ULA revistited.
Just sent email with questions...
Regards.. Mike
Regards.. Mike