DDC Colour Interface for ZX-81

Discussions about Sinclair ZX80 and ZX81 Hardware
Post Reply
User avatar
yerzmyey
Posts: 1240
Joined: Thu May 15, 2008 10:11 am
Location: Rubber Planet
Contact:

DDC Colour Interface for ZX-81

Post by yerzmyey »

I'm wondering how popular the interface was.
Anybody had opportunity to take a look on this? Even buy maybe?

Would be cool if anybody might make some screenshots or photos. Curious if the screen was similar to Spectrum?

I found actually only 1 text about the device (it's below) - and it sounds like it was kinda terrible in usage. Anyway I wonder if there are any schemes to resuscitate the thing by someone with proper skills.




________________________________________
"Interface adds life to ZX-81"

THE DDC Colour Interface allows the ZX-81 user to have a 16-colour display on a TV set. It fits on the back of the ZX-81 and the only internal connection required is to the video lead going into the video modulator.

Control is by turning some of the inverse characters into colour controls. They are in the range from Inverse 4 to Inverse Z and they can no longer be used for graphics. All of the block graphics can still be used. Whatever colour character is printed on the screen it will affect the rest of the line until the end of line or until another colour character is reached. A border around the screen is still maintained in the background colour of red, as when you switch on.

All the colours affect the background colour, as the foreground will normally be black. Inverse graphics will be shown as colour on a black background. The colour character will be shown as a coloured space on the screen. The only difficulty is with editing the lines which contain coloured squares. The normal inverse G, L and K are invisible and there is no way to tell the position of the cursor. You have to watch the blue haze which spreads over the line from the cursor to the end of line and when moving through coloured squares that is extremely difficult. Even when switching-on the computer, the normal inverse "K" cursor is invisible and the only thing the user will see is the blank red screen.

If when switching-on the ZX-81 you get only a blank white screen there is a small resistor inside the unit which can be adjusted to give colour on the screen. That is done easily with a small screwdriver.

The other control inside the box allows you to set shades of colour towards more red or green.

The plastic box is very well made and is fitted like a jigsaw, with no screws, and so can be taken apart and put back together without damage, if with a little difficulty.

The system is very easy to use and fitting it could be much simpler if clips were provided. That would eliminate having to solder wires to fit it on to the video wire going into the modulator.

All the other connections are made by plugging the edge connector of the box into the expansion edge on the back. It can be used with or without a 16K RAM pack but will not work with devices using the upper 32K of memory space. It should certainly put life back into ZX-80s and ZX-81s and is available from ECC Publications, which publishes Sinclair User, for £32.90.
IN NIHILUM REVERTERIS - a big text-adventure game for ZX81: http://tiny.pl/g2m6m
"MONOCHROME" issue 5 - (Spring 2014) free paper/PDF magazine about ZX81: http://tiny.pl/q2m44
ZX81 COMPETITIONS 2007/2009: http://zx81.republika.pl/
User avatar
BrunoFlorindo
Posts: 290
Joined: Sat May 10, 2008 2:46 am
Location: Anaheim, CA, USA

Re: DDC Colour Interface for ZX-81

Post by BrunoFlorindo »

I'm not sure how popular the add-ons for the ZX81 were, but I know that here in the U.S. they weren't popular at all. You see lots of ads on old mags but you rarely see one on eBay, or someone saying 'I have one of those'. It seems there was a boom of interest and new stuff for the ZX81 in its first years, but if quickly stopped. In Europe most people say it became obsolete because of the Spectrum, and in the U.S. it simply faded, little by little, after Timex threw the towel.

Now, if you're like me (an enthusiast, but with no knowledge of electronics), you might see one of these interfaces built one day. One of the Sync magazines that I have (can't remember which one now), has a whole article describing how to upgrade a ZX81 to give it 99% of the Spectrum capabilities, and one of these add-ons was a color interface, similar to the one you describe.

But you have to keep in mind that although we have hardware enthusiasts developing new stuff for the ZX81, it's unlikely someone will look at the old books and mags and say 'I'm going to build the interface that I never had.' The tendency is to build new stuff, not clones of the old.
User avatar
yerzmyey
Posts: 1240
Joined: Thu May 15, 2008 10:11 am
Location: Rubber Planet
Contact:

Re: DDC Colour Interface for ZX-81

Post by yerzmyey »

Hm. I see.

Btw, however it's good that new devices appeare, but actually I'm not sure if it's a good way to abandon the old ones.
Well, at last the schemes should be on the Net. It's like the mentioned before AY interface: well, yes - there are new ones (Turbo Sound, Turbo Sound FM and so on). But at first it would be a good start to reanimate regular humble AY, heh..

So is there some new device working similar to the "DDC Colour Interface"? Is that what You mean?
IN NIHILUM REVERTERIS - a big text-adventure game for ZX81: http://tiny.pl/g2m6m
"MONOCHROME" issue 5 - (Spring 2014) free paper/PDF magazine about ZX81: http://tiny.pl/q2m44
ZX81 COMPETITIONS 2007/2009: http://zx81.republika.pl/
User avatar
BrunoFlorindo
Posts: 290
Joined: Sat May 10, 2008 2:46 am
Location: Anaheim, CA, USA

Re: DDC Colour Interface for ZX-81

Post by BrunoFlorindo »

I think I didn't use the right words. I'm like you, I would like to see old interfaces and hardware projects built.
yerzmyey wrote:...Btw, however it's good that new devices appeare, but actually I'm not sure if it's a good way to abandon the old ones.
I'm actually one of the few who would like to have them built. :)
yerzmyey wrote:...at last the schemes should be on the Net.
Instructions on how to build many interfaces and hardware projects can be found on the magazines, newsletters and book scans. But when it comes to schematics of things that were released commercially, it's a needle in a haystack.
yerzmyey wrote:It's like the mentioned before AY interface: well, yes - there are new ones (Turbo Sound, Turbo Sound FM and so on). But at first it would be a good start to reanimate regular humble AY, heh..
Again, I agree with you. That's why I asked in another post in this forum if you could ask your friend how he built the interface for you. His interface was built for your Timex, but it would be nice to see the schematic, even if it's hand-drawn. :)
yerzmyey wrote:So is there some new device working similar to the "DDC Colour Interface"? Is that what You mean?
Actually I meant the opposite. I was referring to a project that was on a very old magazine, showing how to built a color interface for the ZX81. But it had nothing to do with the DDC.

Another reason why it seems impossible to find info about old interfaces it's because they're really rare, and sometimes the only thing we know about them is what we see on ads on old magazines, nothing else. It seems that here in the U.S. the few hardware hobbyists that were addicted to the ZX81/TS1000 developed their own hardware projects, instead of supporting the commercially released ones. This might or might not have been a good thing.
User avatar
yerzmyey
Posts: 1240
Joined: Thu May 15, 2008 10:11 am
Location: Rubber Planet
Contact:

Re: DDC Colour Interface for ZX-81

Post by yerzmyey »

Bruno:
>Instructions on how to build many interfaces and hardware projects can be found on the magazines, newsletters and book
>scans. But when it comes to schematics of things that were released commercially, it's a needle in a haystack.
--------------
Ah, I see now.
I didn't know.
So Spectrum is in more comfortable situation, there are loads of schemes on the Net. Well, maybe not *so* comfrotable 'cause one must have abilities to "translate" Russian names of electronic-parts (they have their own nomenclature, even for Z80 itself, but their hardware is impressive).

>Again, I agree with you. That's why I asked in another post in this forum if you could ask your friend how he built the
>interface for you. His interface was built for your Timex, but it would be nice to see the schematic, even if it's hand-
>drawn. :)
-------------
Yes, yes. it's kinda problem because they guy, short time after the AY making, has landed in hospital ward of toxicology and then in 'drying-out' if You know what I mean. Heh. Pity, he was fine electronic/soldering-guy.
Finally he left country and I have no contact with him.
However that was me who gave him the schemes. And I can look for them on harddisks (will be hard, too many of them) but remember the schemes are for Spectrum 48Kb and Timex. (I mean the AY interface works even on ZX128K, hehe :) - then it has 2 AYs - but it's *ment* to be used on 48K models :) ).


>Actually I meant the opposite. I was referring to a project that was on a very old magazine, showing how to built a color
>interface for the ZX81. But it had nothing to do with the DDC.
------------
I see, I see. Well, I was just curious anyway. I don't need colour in ZX81 _so much_. But would be nice to have such a device anyway. ;)



>Another reason why it seems impossible to find info about old interfaces it's because they're really rare, and sometimes
>the only thing we know about them is what we see on ads on old magazines, nothing else. It seems that here in the U.S.
>the few hardware hobbyists that were addicted to the ZX81/TS1000 developed their own hardware projects, instead of
>supporting the commercially released ones. This might or might not have been a good thing.
-------------
Ah. I get Your point.
I thought that Timex made the 1000/1500 pretty popular in USA. In early 80s I mean of course.
IN NIHILUM REVERTERIS - a big text-adventure game for ZX81: http://tiny.pl/g2m6m
"MONOCHROME" issue 5 - (Spring 2014) free paper/PDF magazine about ZX81: http://tiny.pl/q2m44
ZX81 COMPETITIONS 2007/2009: http://zx81.republika.pl/
Post Reply