CPLD replacement for ZX8301

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Derek_Stewart
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Re: CPLD replacement for ZX8301

Postby Derek_Stewart » Fri Jul 01, 2022 7:30 pm

tofro wrote:
mk79 wrote:there are only two revisions, the old CLA2310 and the later CLA2345 which added NTFS support.
ZX8301_spares.jpg


No. NTSC, probably? :lol:

Are you sure, Marcel is a brillant programmer, NTFS support would easy for that level of skill


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Re: CPLD replacement for ZX8301

Postby mk79 » Fri Jul 01, 2022 8:49 pm

tofro wrote:
mk79 wrote:there are only two revisions, the old CLA2310 and the later CLA2345 which added NTFS support.
ZX8301_spares.jpg


No. NTSC, probably? :lol:
Damn :mrgreen:


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Re: CPLD replacement for ZX8301

Postby lliont » Fri Jul 01, 2022 11:04 pm

mk79 wrote:Cannot make heads nor tails of the speed difference you report. Are they as consistent as you say? As far as I know there are only two revisions, the old CLA2310 and the later CLA2345 which added NTFS support.


I time the two by hand with my phone's stopwatch so it is not an accurate measurement, but I always got better times with the one of the two ULAs.
I did the tests between them with the memory upgrade on maybe this has to do with the difference.

I also did once a test with a program :

ULAS.jpg
ULAF.jpg


I noticed twice a small black square (smaller than a char) scrolling up with the numbers while I was testing the fast ULA, could it be that it is faster because of a problem with it?
I don't know but it doesn't matter anyway,

What is nice is that the cpld is faster than both.


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Re: CPLD replacement for ZX8301

Postby Nasta » Sat Jul 02, 2022 12:34 am

Checked, mine is the old CLA2310 in a ceramic case, so perhaps one of the first ones...


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Re: CPLD replacement for ZX8301

Postby lliont » Sat Jul 02, 2022 1:01 pm

Nasta wrote:Checked, mine is the old CLA2310 in a ceramic case, so perhaps one of the first ones...


So from CLA2310 to CLA2345 they maybe made some improvements. And to find out one with a CLA2310 on a standard QL could run the simple basic program and time it, CLA2345 takes about 51.5 secs.


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Re: CPLD replacement for ZX8301

Postby lliont » Mon Jul 11, 2022 1:38 pm

New pcb with video buffer arrived and tested OK.
I tested it with the smaller cpld and a 15Mhz oscillator but in the final version I'll use a 30Mhz oscillator.
So I'm waiting for 2 parts to have the 2 different versions of the ULA replacement board ready.

-One with the EPM7128S with the only difference in the behavior of flash bit that complements the colors instead of flashing using a fixed background color
-One with the EPM7160S that will work exactly as the ULA.

On the new pcb there are 5 pin connections available, one pin can provide the Flash signal as output for more colors as an option enabled by shorting another input pin to gnd.

cpld_b.jpg
cpld_b2.jpg


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Re: CPLD replacement for ZX8301

Postby lliont » Sat Aug 06, 2022 12:50 am

I got the EPM7160S and the 30Mhz smd oscillator and tested it with the new pcb and works OK and with the correct flash bit behavior.
It also outputs the flash bit as a signal for any alternative use, when this output is enabled the flashing is disabled. With a simple resistor dac this could be used to produce 16 colors.

Next I may make a pcb with the smd version of epm7128s to reduce the height so it may fit in my QL that has socketed ram or make a different shape pcb for that reason.


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Re: CPLD replacement for ZX8301

Postby lliont » Sat Aug 06, 2022 7:47 am

The EPM7128S that is cheap and available works also with the new pcb and 30Mhz osc. as I wrote with the difference that it flashes the complemented colors instead of the background and this due to resources limitation because there is no room in the cpld to save the background color data. This produces a more intense flashing result.

If there is another cpld with 5V outputs of the same size or bigger that is cheap and available that I am not aware of tell me.
There is also the possibility to use a newer 3.3V cpld (XC95144XL-10TQG100C) and extra circuit for level conversion, I think this is what I'll do next.


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Re: CPLD replacement for ZX8301

Postby ones' complement » Sat Aug 06, 2022 12:51 pm

AFAIK the ATF1508AS can be used in place of EPM7128S (as used here). But at about the same price (ATF1508 is largest in range).


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Re: CPLD replacement for ZX8301

Postby Nasta » Mon Aug 08, 2022 3:57 pm

ones' complement wrote:AFAIK the ATF1508AS can be used in place of EPM7128S (as used here). But at about the same price (ATF1508 is largest in range).


ATF1508S can also be had in a TQFP100 package which is small and thin, so much so that with a multilayer PCB it may be possible to squeeze the whole board within the outline of the original ULA, perhaps a bit wider. It would require surface mount pins to go into the original socket though.



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