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Corona / Cordata monitor (and systems)

PostPosted: Thu Apr 14, 2016 2:34 pm
by RdM

After a move to a much smaller place I'm trying to clear some stuff from storage.

Yet to be looked at are two (or 1 1/2!) Corona luggables, like ... ta-systems ... ch=viewall

But in the meantime I've hauled out the 12" green screen monitor (branded Cordata after Corona sold to them)



which I used to use with a desktop version of the Corona as my first ever PC, mid eighties!
(I see on preview that the images are a bit truncated from the right, but enough is seen, even if no longer centered!)

It had had it's mains plug robbed, so I opened it up to check & test it - spotted one slightly bulging 25V 33000uF PSU filter cap and replaced it with a 105deg 35V one on hand (it is near a 7W resistor!), saw that the mains input went to a pin labelled 240V on the pcb, near a 117V one, (the rear is labelled only 115V) but still fired it up with a series light bulb after fitting a new mains plug in case of other faults!


Nice that the CRT heater glowed, but I wasn't sure about EHT being present (although likely if the heater supplied from the LOPT as often) until I came up with the brainwave of seeing if it would attract, say, a cigarette paper. Very little response to the screen, so I brought it to near the anode cap. Yes!



Now the thing is, I was going to offer this on TradeMe (&or here), as a green screen monochrome monitor, which it is, but then I remembered that the manual mentioned "high resolution graphics" as well as text modes, so clearly not just MDA.
I have the user (and software) manual for the PC's which cover both the luggable and desktop versions.
Also, the graphics resolution at 640 x 325 pixels is higher than CGA (640×200) and nearly up to EGA (640×350).


I see the EGA ( "scans at 21.8 kHz when 350-line modes are used".

I started to wonder what the pin-out is. On the museum links above people have mentioned CGA, but I fear they might be guessing!
(One commentator reckoned on text it was far better than CGA. Then I found I also had a Technical Reference Manual for it.
Layout, block diagrams, circuit diagrams, complete programming reference &etc. Eventually I found the (J7) video connector.


Those pin numbers (on the left) (would have been clearer as a jpg!) don't seem to correspond to CGA or EGA, if correct.
(horiz & vert sync are 8 & 9) ... PINOUT.TXT

So, what to do? Perhaps it is proprietary, and only of use with the original Corona, or maybe I'm missing something?

If the former, perhaps there's someone on here (or if not, TradeMe) has a has a Corona/Cordata desktop that could use it.

Does anyone have any more knowledge of these PCs?

Since I've closed it back up I don't fancy opening it up again to try to trace out the wiring - the stand has to come off too, and I feel I've spent enough time on it already at the moment!

Next I'll have a look at the luggables, but I have to clear some space in the flat before I get them out of storage!

Cheers, and thanks for reading!

~ Ross.

Re: Corona / Cordata monitor (and systems)

PostPosted: Thu Apr 14, 2016 5:45 pm
by SpidersWeb
That's a bit oddball. Doesn't really seem compatible with any predefined standard. I don't own any Corona gear but my Apricot and Wang PC have similar oddball resolutions too - 720x400 and 800x300 - both TTL green screen mono displays.

I'd probably only want to use this with the original hardware it was intended. Perhaps the original computer itself was able to emulate CGA graphics and that's why they're mentioning it?

Loved the cig paper trick!

Re: Corona / Cordata monitor (and systems)

PostPosted: Thu Apr 14, 2016 9:30 pm
by RdM
I think you're right;- only good for compatible Corona/Cordata units.
That specific video chipset in hardware, & its programming (& wiring).

I think CGA mentions were either in comparison, as better than, or as quick assumptions, guesses. So far.

At least when I can dig the luggables out, there is a complete manual for one.

Thanks! Yeah, once I realised the response at the back, I had to use a 3rd hand;- one on the camera, another on a mirror, for a bit of extra light!

Just to record it. ;=})