OSI 600D Superboard Build

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rubber_jonnie
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Re: OSI 600D Superboard Build

Post by rubber_jonnie »

stephen_usher wrote: Fri Mar 29, 2024 12:05 pm I think the fuzzy video thing is due to the change in speed (and manufacturing process) between now and the 1970s.
I wouldn't be surprised if it's that at all.
stephen_usher wrote: Fri Mar 29, 2024 12:05 pm Indeed, I'm surprised that the BoM didn't state a specific manufacturer's part as the timings differed so greatly back in the day. There are many systems where the service manual states manufacturer and even down to build date for replacement parts.
It think this was in part due to Ohio Scientific providing all the parts in the kit, so you didn't buy a bare board back in the day and supply all your own components. I haven't seen any indications that it came as a bare board at this point, but I could be wrong.

The BoM does state alternatives, but in the case of U21, it's another LS04. I've also ordered some 7404's to see how they fare just out of curiosity.

I've just set up the jumpers for cassette operation, so need to see if that's working now. More fun and games, then I can build the 610 expansion board :)
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, so I tried this which I had kicking round in a drawer.

It's just a composite mod I made for an Atari 2600 (I think) that I abandoned and bought a ready made one for that included a nice cable and audio built in too.

IMG20240329145534.jpg
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IMG20240329150554.jpg
IMG20240329150554.jpg (174.75 KiB) Viewed 240 times

And there is a definite improvement with the LCD.

This is before:

IMG20240329145249.jpg
IMG20240329145249.jpg (289.46 KiB) Viewed 240 times

This is after:

IMG20240329145340.jpg
IMG20240329145340.jpg (301.58 KiB) Viewed 240 times

However this is the CRT with it:

IMG20240329145453.jpg
IMG20240329145453.jpg (216.45 KiB) Viewed 240 times

And this is the CRT without:

IMG20240329145649.jpg
IMG20240329145649.jpg (176.34 KiB) Viewed 240 times

Personally I prefer the CRT without.

I think there is scope for both a CRT out and a VGA out, since with the mod I can get the pot at R58 adjusted well to work on both outputs.
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 »

I've been looking at cassette saving for the OSI today for fun ( :excited: ) and have hit another issue, possibly another dead IC, and though the TL866 says otherwise, I have ordered a replacement just in case. I also managed to find some 7476's as well so those are also on the way.

It would be nice if I actually had the IC's I need in stock, but like with capacitors, it's just never the case :pullhair:

When I run the 'SAVE' command (It's a weird and wonderful way to save, but that's another story) I can see the data leaving the 6850 and getting to where it should do in the last IC in line, U64, a 74LS76.

However, it should then output from pin 15 to the other gates, but I just see a constant square wave...

I don't have any shorts, but what's coming out of pin 15 should represent what is going into pins 2,4 & 16, and it just isn't. I did also remove the IC but there was nothing on pin 15 coming externally, so it has to be coming from the IC. So I lifted pin 15 and it's definitely being generated in the LS76.

The BoM says SNC5476J, 7476 and 74LS76, so it's looking like another possible timing issue due to a modern chip.

I probably won't use cassette much, but I want as much working before I start off on the 610 expansion board.
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 »

rubber_jonnie wrote: Fri Mar 29, 2024 5:52 pm I also managed to find some 7476's as well so those are also on the way.
Annoyingly the supplier of the 7476's had a stock error and canceled my order. They issued the refund PDQ, but I'd rather have had the IC's. :pullhair:

EDIT - Just found some at Cricklewood Electronics, I certainly recommend them as a supplier.
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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HigashiJun
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Re: OSI 600D Superboard Build

Post by HigashiJun »

rubber_jonnie wrote: Mon Apr 01, 2024 9:29 am
Annoyingly the supplier of the 7476's had a stock error and canceled my order. They issued the refund PDQ, but I'd rather have had the IC's. :pullhair:

EDIT - Just found some at Cricklewood Electronics, I certainly recommend them as a supplier.
:dizzy:
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stephen_usher
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Re: OSI 600D Superboard Build

Post by stephen_usher »

rubber_jonnie wrote: Mon Apr 01, 2024 9:29 am EDIT - Just found some at Cricklewood Electronics, I certainly recommend them as a supplier.
Yeah. They're reliable for old parts, though not cheap.
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 »

HigashiJun wrote: Mon Apr 01, 2024 11:21 am
rubber_jonnie wrote: Mon Apr 01, 2024 9:29 am
Annoyingly the supplier of the 7476's had a stock error and canceled my order. They issued the refund PDQ, but I'd rather have had the IC's. :pullhair:

EDIT - Just found some at Cricklewood Electronics, I certainly recommend them as a supplier.
:dizzy:
Exactly...
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 »

stephen_usher wrote: Mon Apr 01, 2024 11:43 am
rubber_jonnie wrote: Mon Apr 01, 2024 9:29 am EDIT - Just found some at Cricklewood Electronics, I certainly recommend them as a supplier.
Yeah. They're reliable for old parts, though not cheap.
Yes, definitely not cheap at all, but at the moment I'll take reliable over cheap!
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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HigashiJun
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Location: Tokyo

Re: OSI 600D Superboard Build

Post by HigashiJun »

rubber_jonnie wrote: Mon Apr 01, 2024 12:13 pm Yes, definitely not cheap at all, but at the moment I'll take reliable over cheap!
A wise man decision...

8-)
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chronicthehedgehog
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Re: OSI 600D Superboard Build

Post by chronicthehedgehog »

I've got 40 SN74LS76AN on my shelf if you need more. I bought a good job lot a couple of years ago. I got a bit OCD about 74X at the time :D
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