CPLD replacement for ZX8301

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bwinkel67
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Re: CPLD replacement for ZX8301

Postby bwinkel67 » Thu Jun 23, 2022 6:55 am

lliont wrote:
bwinkel67 wrote:I've found ZX8301's hard to find. I located one source (Mutant Caterpillar) for a reasonable price, but glad a replacement is out there.


If you live in UK the price is reasonable, I live in Greece and a ZX8301 from ebay with price 35 pounds cost me 62 pounds after customs (Brexit) and shipping fees.
With that amount I developed the replacement, with about double the sum I could have bought another QL maybe.


I'm in the US. I bought it from Mutant Caterpillar for £20 but shipping cost £400...well, I didn't have to pay for that as I had it shipped to a friend's parents house in the UK for £2 and my friend visited UK and flew back (the £400 was for the flight...well, I don't actually know how expensive a flight form US to UK is).


Derek_Stewart
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Re: CPLD replacement for ZX8301

Postby Derek_Stewart » Thu Jun 23, 2022 10:56 am

...Should of used surface mail.


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Derek
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Re: CPLD replacement for ZX8301

Postby Derek_Stewart » Thu Jun 23, 2022 11:01 am

Hi

I did a design for a schmatic design for an internal expansion port, connecting to the CPU & 8301 sockets solving the height problem with the two sockets. It did not get made, mainly due too many other things.

I think the CPLD 8301 circuit could be integrated, maybe the code could be adoater to display 512x512, eith the Minerva Second Screen enabled.

This is only an ideas changes to operating system maybe required


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Derek
lliont
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Re: CPLD replacement for ZX8301

Postby lliont » Thu Jun 23, 2022 11:04 pm

The flickering is solved, it just needed a change in horizontal blanking start/duration and now it is very stable in both screen resolutions.
Only thing left is the flash that needs few more macrocells, whatever I tried it won't fit in EPM7128, so I have to wait I think it will take a few weeks to receive the EPM7160.


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ones' complement
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Re: CPLD replacement for ZX8301

Postby ones' complement » Fri Jun 24, 2022 8:15 am

Big difference in price and availability between EPM7128 and EPM7160 :(

...and that is if you are lucky enough to get JTAG unlocked pulls (scroll down to 'So here it is in a nutshell:').

Added: AFAIK only EPM7000S series can be JTAG programmed (i.e. using USB blaster): EPM7128S... / EPM7160S...
Last edited by ones' complement on Fri Jun 24, 2022 12:43 pm, edited 1 time in total.


lliont
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Re: CPLD replacement for ZX8301

Postby lliont » Fri Jun 24, 2022 10:39 am

ones' complement wrote:Big difference in price and availability between EPM7128 and EPM7160 :(

...and that is if you are lucky enough to get JTAG unlocked pulls (scroll down to 'So here it is in a nutshell:').


Thanks for the info.
The new pcb will work with both 128 and 160, If one doesn't care about the flash bit, he can use the EPM128 that is cheap and available and I'll put an alternative flash behavior in like flashing not only the foreground but all the pixels or something, this fits.


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RalfR
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Re: CPLD replacement for ZX8301

Postby RalfR » Fri Jun 24, 2022 10:45 am

lliont wrote:The new pcb will work with both 128 and 160, If one doesn't care about the flash bit, he can use the EPM128 that is cheap and available and I'll put an alternative flash behavior in like flashing not only the foreground but all the pixels or something, this fits.
What I haven't really understood: How have you read the contents of the Ula to know, what it is doing?


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mk79
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Re: CPLD replacement for ZX8301

Postby mk79 » Fri Jun 24, 2022 10:50 am

RalfR wrote:What I haven't really understood: How have you read the contents of the Ula to know, what it is doing?
Nasta has written whole dissertations on the behavior of ZX8301 on this forum, basically all there is to know.


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Re: CPLD replacement for ZX8301

Postby lliont » Fri Jun 24, 2022 11:10 am

What about this alternative, I think its nice

https://drive.google.com/file/d/1oDysjNLvDN4JmFzGGnZ9PvhmNvXh_Ltt/view?usp=sharing

Color complement.
Last edited by lliont on Fri Jun 24, 2022 11:18 am, edited 1 time in total.


lliont
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Re: CPLD replacement for ZX8301

Postby lliont » Fri Jun 24, 2022 11:16 am

RalfR wrote:What I haven't really understood: How have you read the contents of the Ula to know, what it is doing?


I studied Nasta's description of the ULA. It's totally accurate and I mentioned that at my fb post. Nasta is great, respect.



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