ULA revistited.

Any discussions related to the creation of new hardware or software for the ZX80 or ZX81
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RetroTechie
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Re: ULA revistited.

Post by RetroTechie »

Very nice work Andy! 8-)

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)... :?:
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Andy Rea
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Re: ULA revistited.

Post by Andy Rea »

ah well.... they came along at the right price, NOS :D 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 :lol: that will give me plenty of tinkering room for the ones in my Zeddies 8-)

Regards Andy
what's that Smell.... smells like fresh flux and solder fumes...
Mike3
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Re: ULA revistited.

Post by Mike3 »

I am intrested also...

Mike
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Paul
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Re: ULA revistited.

Post by Paul »

Andy Rea wrote:yeah there are a few io's spare :lol: that will give me plenty of tinkering room for the ones in my Zeddies 8-)
That's what I am loving aboute it!!!
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.
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Andy Rea
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Re: ULA revistited.

Post by Andy Rea »

I think i am just about done with the code for the cpld :D

all previously mentioned mentioned features work in ZX81 mode :D

Rompatch is not implemented in ZX80 mode.

Turbo works in ZX80 mode :D

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...
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Andy Rea
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Re: ULA revistited.

Post by Andy Rea »

Well there's an interesting thing.....

i have an almost unmodified ZX81 issue 1, with a ROM labeled
SINCLAIR
RESEARCH 8306P7

D2364C 649 (c) 1981
When running Turbo mode, it seems like this rom is borderline for access speed as it would sometimes crash but always when running turbo :?

I replaced the ROM with one out of another machine labeled
<motorola symbol>
ZCM38818P
8312
and the problem has gone away...

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...
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Andy Rea
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Re: ULA revistited.

Post by Andy Rea »

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
what's that Smell.... smells like fresh flux and solder fumes...
Mike3
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Re: ULA revistited.

Post by Mike3 »

Very good!.. Ii have many ZX81's dead because of the ULA's

is this ready for sale?

Mike
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Andy Rea
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Re: ULA revistited.

Post by Andy Rea »

yep :D
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Mike3
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Re: ULA revistited.

Post by Mike3 »

Just sent email with questions...

Regards.. Mike
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