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dk'tronics 4K Graphics ROM

Posted: Fri Jun 03, 2016 2:15 pm
by Alistair
Got the above chip in my ZX81. Not sure if it's a common thing or not but it was installed by a mate whose ZX81 I bought when he moved on to being a Spectrum owner.

The manual indicates that there are 8 separate graphics character sets that can be used (including the standard Sinclair set) and also the ability to create two sets of user defined graphics.

Re: dk'tronics 4K Graphics ROM

Posted: Fri Jun 03, 2016 2:29 pm
by mrtinb

Re: dk'tronics 4K Graphics ROM

Posted: Fri Jun 03, 2016 2:41 pm
by Alistair
Yep, that's the one, based on the manual I have.

Re: dk'tronics 4K Graphics ROM

Posted: Mon Jun 06, 2016 11:26 pm
by gammaray
Are there complete schematics available? I saw some through the link but not sure if that is enough to reproduce.

Re: dk'tronics 4K Graphics ROM

Posted: Mon Jun 13, 2016 8:15 pm
by XavSnap
Are there complete schematics available?
It's a basic ROM expansion, base on the $2000 offset.
A single IR redirection to the $2000 memory bloc.

Just get a ROM expansion card set at $2000 to $3FFF (low memory)

Re: dk'tronics 4K Graphics ROM

Posted: Tue Jun 14, 2016 1:09 am
by XavSnap
Internationals pictures...
xur3.JPG
xur3.JPG (51.2 KiB) Viewed 2078 times
xur1.JPG
xur1.JPG (69.9 KiB) Viewed 2078 times
xur2.JPG
xur2.JPG (72.15 KiB) Viewed 2078 times

Re: dk'tronics 4K Graphics ROM

Posted: Tue Jun 14, 2016 5:04 pm
by 1024MAK
gammaray wrote:Are there complete schematics available? I saw some through the link but not sure if that is enough to reproduce.
I have reverse engineered a schematic, but it only exists as a hand drawn draft on paper at the moment. When I have time, I will redraw it in a CAD program and then post it in this thread. You will have to wait for a while though, as I am rather busy at the moment.

Mark

Re: dk'tronics 4K Graphics ROM

Posted: Tue Jun 14, 2016 7:43 pm
by sirmorris
Is it done yet?

Re: dk'tronics 4K Graphics ROM

Posted: Tue Jun 14, 2016 10:16 pm
by 1024MAK
:lol:

Re: dk'tronics 4K Graphics ROM

Posted: Wed Jun 15, 2016 12:45 am
by XavSnap
but it only exists as a hand drawn draft on paper at the moment.
This ????
mak.jpg
mak.jpg (44.66 KiB) Viewed 2034 times