OSI 600D Superboard Build

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stephen_usher
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Re: OSI 600D Superboard Build

Post by stephen_usher »

I do think that you have a working system there, you just can't see it, other than on the oscilloscope, which isn't that useful. :-)
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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rubber_jonnie
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Re: OSI 600D Superboard Build

Post by rubber_jonnie »

stephen_usher wrote: Sun Feb 04, 2024 4:39 pm I do think that you have a working system there, you just can't see it, other than on the oscilloscope, which isn't that useful. :-)
Me too.

Shame it doesn't have any sort of X/Y output, then I could set my scope up to be my display :)
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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Re: OSI 600D Superboard Build

Post by stephen_usher »

I wonder if you could use the information from the ZX81 signal conditioning to get the OSI composite video good enough: https://www.evolutional.co.uk/post/zx81 ... ning-mods/
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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rubber_jonnie
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Re: OSI 600D Superboard Build

Post by rubber_jonnie »

stephen_usher wrote: Sun Feb 04, 2024 10:58 pm I wonder if you could use the information from the ZX81 signal conditioning to get the OSI composite video good enough: https://www.evolutional.co.uk/post/zx81 ... ning-mods/
Hmm interesting 🤔
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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rubber_jonnie
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Re: OSI 600D Superboard Build

Post by rubber_jonnie »

OK folks, this little fella arrived today:

PXL_20240207_221000752.jpg
PXL_20240207_221000752.jpg (235.13 KiB) Viewed 148 times
It had a cold solder joint on the TV on switch, however I was able to fix it and get it all back together in about half an hour. Another win for my little rechargeable soldering iron.

It's a 5.5" black and white TV from Plustron, but the key thing is that it has a composite input. What you're seeing on screen right now is the output from the OSI :)

Zooming in I see this:

PXL_20240207_221000752~2.jpg
PXL_20240207_221000752~2.jpg (306.71 KiB) Viewed 148 times

You may have to zoom in further on this web page, but when you do, you might just see characters in amongst all that mess!! Also with the monitor ROM in I can elicit a response by hitting break, which changes the image, so I think I have a machine that is at least working in some capacity.

I have tried tuning using R58, and I also tweaked the V-Hold on the TV , and the picture does change, though it still doesn't display properly as above. I'll take this as a small win though.

Apparently if I drop to BASIC and type SAVE then return it'll show output on pin 6 of the 6850, so I may try that tomorrow.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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stephen_usher
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Re: OSI 600D Superboard Build

Post by stephen_usher »

I'm guessing that the telly doesn't do 60Hz, just 50Hz.

I wonder if you can slow the OSI's clock down by 1/6th so it does 50Hz video. Hehe. Oh, of course it'll have the wrong number of lines then. Bother.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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rubber_jonnie
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Re: OSI 600D Superboard Build

Post by rubber_jonnie »

stephen_usher wrote: Wed Feb 07, 2024 11:31 pm I'm guessing that the telly doesn't do 60Hz, just 50Hz.

I wonder if you can slow the OSI's clock down by 1/6th so it does 50Hz video. Hehe. Oh, of course it'll have the wrong number of lines then. Bother.
Yes, that's a possibility for sure, and something I'd not considered (Annoyingly). Best I can do is 90% of 4Mhz...

Whilst it may not do 60 Hz, it has helped substantially in that I now know it's working in some sort fashion, so that is helpful.

I don't think I tried connecting to my main LCD tv, as that does support 60Hz. I know it might not like the signal, but I have to try. I only previously tried it on my RetroTink, and to be fair I haven't tried again since fixing the clocks. What have I got to lose?
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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rubber_jonnie
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Re: OSI 600D Superboard Build

Post by rubber_jonnie »

So Klyball, the designer of the reproduction PCB said this over at OSIWeb:

"I'm not a expert on the signal but it could be a pal/ntsc issue. I'm comparing the 2 schematics uk101 to the 600 it looks like there doing the timing for hs and vs a bit different."

Hmm, interesting. I presume then that the guy I got the board from has a display that can do either PAL or NSTC, now wondering how I'm going to get this thing to display at all.

I don't know a lot about the video signals, but I didn't realise that composite could be PAL or NTSC. Clearly I got that wrong having just read this: https://en.wikipedia.org/wiki/Composite ... rrelevant.

So I've managed to find an NTSC to PAL converter on Amazon so I've ordered one to see if it helps me out at all. It is switchable too, so will also do PAL to NTSC.

Should arrive Saturday, so lets keep fingers crossed!!!
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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stephen_usher
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Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
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Re: OSI 600D Superboard Build

Post by stephen_usher »

Hopefully the new box does the trick. It'll have to have a frame buffer to read the frame from the source, store it and then write it out at a different frequency and number of lines (and potentially colour encoding).

With respect to "composite video", you have to think of it as just the TV signal before it gets modulated for transmission over RF, so it would be whatever the TVs in the region expect for their input. So not only will the number of frames per second change but the number of scan lines and the colour encoding (not an issue here).
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
User avatar
stephen_usher
Posts: 5343
Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
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Re: OSI 600D Superboard Build

Post by stephen_usher »

By the way, if you have one of these devices it may be able to do the business:

61IWL4KW7CL._AC_SL1000_.jpg
61IWL4KW7CL._AC_SL1000_.jpg (43.25 KiB) Viewed 51 times
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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