OSI 600D Superboard Build

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rubber_jonnie
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Re: OSI 600D Superboard Build

Post by rubber_jonnie »

chronicthehedgehog wrote: Mon Apr 01, 2024 1:01 pm 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
Much appreciated.

I do have some coming, but will give you a shout if I run into problems, thanks.
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 »

Quick update, I put together a quickie video buffer that slots into the 2 unused sockets at the top of the board, and picks up 5v & GND to power it.

IMG20240401160112.jpg
IMG20240401160112.jpg (307.36 KiB) Viewed 250 times

Video out on my LCD is pretty nice from it and I now have 2 outputs, one for CRT and one for LCD :D

IMG20240401160702.jpg
IMG20240401160702.jpg (235.75 KiB) Viewed 250 times
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 »

:dualthumbup:
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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HigashiJun
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Re: OSI 600D Superboard Build

Post by HigashiJun »

:girldance:
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rubber_jonnie
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Re: OSI 600D Superboard Build

Post by rubber_jonnie »

Well, my 7476's arrived and it's made no difference to the tape output. Hmm

What's weird though is that pin 11 outputs to R56, a 100K resistor, and on the IC side there is a signal, but on the other side of the resistor, that connects to pin 9 of J2, there isn't. t

Pin 9 of J2 connects to pin 7, the cassette out, via a voltage divider.

The resistor measures fine, however there is a capacitor, C13 between the output of R56 and GND. Could I have got this cap wrong as well? So I need to check that and see if lifting one leg changes what I see on pin 9 of J2.

It should be 0.01 uF. I can at least check that, though for now further testing has to go on hold as an LS163 in my video circuit has died and guess what? I don't have any spares!!!

I have, I'm sure, nearly every 74 series IC ever made (Maybe I'm exaggerating :) ), but I never have the one I actually need. So the OSI will have to wait a couple of days.

More and more I'm thinking I accidentally powered my bench PSU on at 8.5v and that's why so many have died. Meh!
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 »

Grrr.... Silly chips.

Do you see a signal if you lift the non-chip side of the resistor and/or remove the cap?
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 Apr 03, 2024 12:59 pm Grrr.... Silly chips.

Do you see a signal if you lift the non-chip side of the resistor and/or remove the cap?
Annoyingly I didn't get that far before the LS163 in the video circuit decided to go bye bye.

I will probably pull one leg of the cap to check the value at least, and I may be able to blind type to see if I get anything with the cap lifted/removed.

Just wondering if I've filtered myself again...
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 »

One other thing I'll be doing once I have this up and running again is to fix the problem of the display being shunted 2 characters to the right, which is very noticeable on the LCD.

So I have modded the ROM file at location $7E0 after discussing over at OSIWeb, and once I have some new ROMs (My current ROMs aren't erasable) I'll flash it.

It just requires that value to be changed from $65 to $63, which will shift it 2 columns left. Increasing the value moves it a column to the right, decreasing moves to the left. Apparently you can also add or subtract $40 from that value to move the bottom left corner up or down too, however that's not necessary for me.

I'll report back on the results.
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 »

:crossed1:
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
rubber_jonnie
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Re: OSI 600D Superboard Build

Post by rubber_jonnie »

Well I lifted a leg on the cap and tested it, it is indeed the correct value, 0.01uF. I'll leave the leg lifted until I can get the video fixed and will look at it again then.

The LS163's are from a supplier who I trust so I expect them to be here in the next few days.
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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