QL-VGA

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mk79
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Re: QL-VGA

Postby mk79 » Mon Jan 13, 2020 9:10 am

Dave wrote:Since the NTSC flag in the 8301 allows 60Hz output, would that simplify things? Or is the 60Hz tied strictly to different resolutions?
If you've got some 60Hz output you can probably get away with just using a line doubler (like OSSC) and have a standard compliant output, too. But then you have all the problems that a 60Hz poll on a QL would imply, most software was never really designed for this.


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Re: QL-VGA

Postby Dave » Mon Jan 13, 2020 3:43 pm

mk79 wrote:
Nasta wrote:As far as I know, there isn't a version of the 8301 ULA that actually implements this. It was obviously planned but may never have been implemented.
Actually I tried "POKE hex('18063'),64" on my German issue 6 or something QL and the display gets weird and the poll frequency changes to 60Hz, so I think NTSC with the 8301 is a thing ;)


Yep. :D


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Re: QL-VGA

Postby Nasta » Tue Jan 14, 2020 11:08 pm

mk79 wrote:
Nasta wrote:As far as I know, there isn't a version of the 8301 ULA that actually implements this. It was obviously planned but may never have been implemented.
Actually I tried "POKE hex('18063'),64" on my German issue 6 or something QL and the display gets weird and the poll frequency changes to 60Hz, so I think NTSC with the 8301 is a thing ;)


Inreresting, I've seen several versions of the 8301, but none had that. Does the NTSC flag work on both MODE4 and MODE8? It would have to limit the number of display lines so in 60Hz there would be a lot of vertical overscan.
Can you check some more so I'll add it to the 8301 documentation thread? Can you tell me what the markings on your 8301 are?


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Re: QL-VGA

Postby papanillu » Thu Jan 16, 2020 5:55 pm

Hi
I should buy one of these, (or maybe two) if they become avaiable.


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Re: QL-VGA

Postby mk79 » Sat Jan 18, 2020 9:09 am

Nasta wrote:Interesting, I've seen several versions of the 8301, but none had that. Does the NTSC flag work on both MODE4 and MODE8? It would have to limit the number of display lines so in 60Hz there would be a lot of vertical overscan.
Can you check some more so I'll add it to the 8301 documentation thread? Can you tell me what the markings on your 8301 are?
I didn't check all my ZX8301 (got 10 or so), but the 6 or so I did check all have date codes from 1985:
zx8301.jpg
The line timings don't change at all, it just displays less lines to meet the 60Hz. PAL mode (pink is CSYNC, blue is BLUE with a completely white picture):
QL_Video_PAL.png
Same view with NTSC. Apparently there are now about 192 white lines (the counter is a btit jumpy between 190 and 192):
QL_Video_NTSC.png
The vsync front porch is apparently 32 lines:
QL_Video_NTSC_FP.png
The back porch curiously seem to be 34 lines
QL_Video_NTSC_BP.png

All a bit weird but that's what my scope says at least. Mode 4 and mode 8 seem to be identical timing wise.

Cheers, Marcel


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Re: QL-VGA

Postby NormanDunbar » Sat Jan 18, 2020 8:43 pm

Hi Marcel,

I always hated you for being so young, talented and for having a brain the size of a planet, but now I find out that you have a Rigol scope too. ;) ;) ;)

I have to make do with a EspoTek Labrador. https://espotek.com/labrador/product/es ... dor-board/

However, I have two! :D :D

Cheers,
Norm

PS. Joking of course!.


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Re: QL-VGA

Postby janbredenbeek » Sat Jan 18, 2020 11:31 pm

mk79 wrote:
Nasta wrote:Interesting, I've seen several versions of the 8301, but none had that. Does the NTSC flag work on both MODE4 and MODE8? It would have to limit the number of display lines so in 60Hz there would be a lot of vertical overscan.
Can you check some more so I'll add it to the 8301 documentation thread? Can you tell me what the markings on your 8301 are?
I didn't check all my ZX8301 (got 10 or so), but the 6 or so I did check all have date codes from 1985

On my D15 QLs, the POKE has no effect. But your 8301 is a CLA2345, this is different from mine (CLA2310, date code 8453).
(I have two issue 5 QLs and two issue 6, all are plain UK models but some have a 220V power supply rather than 240V).

Jan


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Re: QL-VGA

Postby mk79 » Sun Jan 19, 2020 10:22 am

NormanDunbar wrote:I always hated you for being so young, talented and for having a brain the size of a planet, but now I find out that you have a Rigol scope too. ;) ;) ;)
Now, if I had done this using one of the scopes at work, ranging from some 4000€ Agilents to 15000€ LeCroys, I would understand the envy, but the Rigol? :-D :-D It's less than 400€ nowadays, what are you waiting for ;) Of course mine was a business expense and paid for by QL-SD sales, so thanks everybody :-)

Cheer, Marcel


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Re: QL-VGA

Postby mk79 » Sun Jan 19, 2020 10:25 am

janbredenbeek wrote:On my D15 QLs, the POKE has no effect. But your 8301 is a CLA2345, this is different from mine (CLA2310, date code 8453).
(I have two issue 5 QLs and two issue 6, all are plain UK models but some have a 220V power supply rather than 240V).
Interesting. I only have German QLs, which automatically seems to imply that I only have issue 6 QLs. I've shot a few ULAs during my experiments, but the replacement chips were all CLA2345, too. Do your issue 6 QLs also have the 2310?

Cheers, Marcel


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Re: QL-VGA

Postby janbredenbeek » Sun Jan 19, 2020 12:12 pm

mk79 wrote:
janbredenbeek wrote:On my D15 QLs, the POKE has no effect. But your 8301 is a CLA2345, this is different from mine (CLA2310, date code 8453).
(I have two issue 5 QLs and two issue 6, all are plain UK models but some have a 220V power supply rather than 240V).
Interesting. I only have German QLs, which automatically seems to imply that I only have issue 6 QLs. I've shot a few ULAs during my experiments, but the replacement chips were all CLA2345, too. Do your issue 6 QLs also have the 2310?

Yes, these are Issue 6 QLs with (originally) JS ROMs.
But AFAIK the German QLs were made by Samsung (SG-xxxxxx serial numbers with Issue 7 boards)?

There's a lot of info on build standards on Urs König's page here: http://www.sinclairql.net/build_standards.html

cheers, Jan.



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