If you want to ask questions about how the machine works, peculiar details, the differences between models, here it is !
How to program the oric hardware (VIA, FDC, ...) is also welcome.
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Voyageur
- 2nd Star Corporal
- Posts: 26
- Joined: Thu Oct 18, 2018 8:25 am
- Location: Sydney
Post
by Voyageur » Fri Jul 19, 2019 9:34 am
Its reference is R26 and its value is 2k2... It pulls down to ground the line between ULA and 74LS365 / Prom 256x4....
Is it an help / a need for generating the Red color ? Why is there nothing like that with the Green and the Blue colors ?
Or is it only used with the PROM ?
I don't understand why there is such a single resistor just there...
Does anybody have information about it ?
Thanks for teaching me !

Oric Atmos : a new life !
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mikeb
- Flying Officer
- Posts: 138
- Joined: Wed Sep 05, 2018 8:03 pm
- Location: West Midlands, UK
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Contact:
Post
by mikeb » Fri Jul 19, 2019 5:54 pm
Secret purpose.
Gateway to Narnia.
Do not mess with it
It's been sat there looking out-of-place, and yet completely innocent, all these years, and its purpose is to stop that video "output" line accidentally floating up to +5v. Spoiler Alert: This pin is also an input, but its not documented, until I fell over it while doing this ...
http://oric.signal11.org.uk/files/pub/u ... Schems.pdf
The answers are in the above!
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Voyageur
- 2nd Star Corporal
- Posts: 26
- Joined: Thu Oct 18, 2018 8:25 am
- Location: Sydney
Post
by Voyageur » Sat Jul 20, 2019 5:13 am
Thank you Mikeb !
That is bright ! I couldn't imagine the concerned chip was the ULA !
A different design for the Red ! A pin with Output and Input :
19 OUT Video R
+ IN VC Reset 2
Now I can see why there is a "lost" resistor.
What a good job made with this document ! Congrats !
Merci encore !

Oric Atmos : a new life !