OSI 600D Superboard Build

[rubber_jonnie]

Woo hoo!!

My LS163's just arrived so the 600 should hopefully be back up and running very soon!!

[stephen_usher]

[rubber_jonnie]

And we have video again!!!

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And I've made a slight tweak to the value in the monitor ROM at $7E0 from 65 to 64, and it's shifted over 1 column left now, which is enough.

A value of 63 is too far, and ideally the value would be 63.5, but we know that's not going to happen.

It's close enough for 24 columns to work.

[stephen_usher]

Yay!

[stephen_usher]

So, next is the tape interface... Remove the cap and see what happens. I dare you.

[rubber_jonnie]

So, next is the tape interface... Remove the cap and see what happens. I dare you.

Lol, I already did and it didn't help. I have a concern that my 'scope probe maybe faulty so going to try another. Might just be me being paranoid

I also have a test routine that is in the service manual, so going to try that, see what it turns up.

[rubber_jonnie]

I've been doing a bit of 'burn in' with the OSI just to try and flush out any more bad IC's, and so far it's looking good

Of interest is the power consumption:

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And that's just for the base machine with 8KB of RAM and not a lot of other stuff. I'm wondering how much extra load the 610 expansion board will add with the extra RAM and FDD interface.

Yep I know the voltage is a bit higher, but well within spec and only set that way so I could check some voltages expected on the cassette circuit. They're low at 5v, and still low at 5.2v, but I'm honestly not sure if it will make much difference to the circuit on account of them being well into the TTL high range even if not the same as the service manual states.

I guess we'll see. Off to set it back to 5v now.

IMG20240409130222.jpg (177.19 KiB) Viewed 9021 times

There you go

[stephen_usher]

One and a half amps is quite a lot. I wonder what's burning all that electricity.

[rubber_jonnie]

One and a half amps is quite a lot. I wonder what's burning all that electricity.

I think, and I'd have to go and check, but the specced PSU in the manual is for 6A, which would give headroom for the 610 to be added. That is with just a simple basic program running that prints out all the available characters on screen then starts again.

I'll see if I can get a thermal pic of what's the hottest

[stephen_usher]

Actually, thinking about it, 1.5A at 5V is only 7.5 watts. It just seems a lot.