New ZX80 boards

[zx80nut]

Hi Lee.
The replica layouts on my page are very accurate (within a fraction of a mm) of the original board, so the centre of the keypad spirals (centred between the keypad contact through-holes) can to used to confirm the layout of the switches on your board from the edges.
I've spend many (too many, if you were to ask my wife) hours making the layouts accurate to the original, by overlaying the re-drawn board with high-res scans of the original, then taking actual measurements to confirm.

All the best with your development - looks great

Regards.

Grant.

[Mike3]

So ... update on the New ZX80 boards?


Mike

[KnightFire]

What happened with these boards?

At one point I had actually prepaid for a board for my son and I to assemble as a summer project, but was asked by Lee if it was OK to send it to Germany instead - we capitulated, but I regret that decision now, as all the boards appear to have worked.

[Paul]

The three boards all had some troubles.
Jens board did not start the clock due to a defective chip, all our European boards had problems with the shifted keys.
Jens and me switched to different diodes, different resistors and different chips 74hct instead of LS.
Our two German boards are running flawlessly.
Last time I heard from sormorris board it still had keyboard problems. No idea if he ever got it working.
@SirMorris and Jens:
could you bring your board to Mahlerts for a photo session of all three European boards?
Maybe one of us would be willing to give his running Lee80 to you?
I still have one unbuilt zx80 board from Martin lukasek.
And one that is built and running.
It's based on grants first PDF version.
Would you like me to ask if Martin still has a board?
I could be persuaded to give away my unbuilt board as I would like to switch to the latest version of grants PDF.
I see what I can do for you.
In our German forum Pokemon was thinking about a new board layout. Maybe this could be interesting for you too.
In case it comes close to production I will post news here in case someone would be interested.
Kind regards
Paul

[KnightFire]

Wow, Paul, many thanks for the prompt reply. Awe shoot, guess my memory failed me - I thought they all worked.

I am actually a proud owner of one of Martin's boards as well - beautiful wee beasties!
I'm also a new owner of an issue 3 UK ZX80!

I'd love to get my hands on a ZX81 board based on the ZX80, but with no adapters or daughter board, and with (VGA) video out.

PS
Is there any info on the different ZX80 mobo issues?

[Paul]

I never saw a zx81 board with VGA out.
Only the ax81 which is "only" an emulation.
Biggest problem, as always, are the different modes to create hires.
That makes it close to impossible to copy a frame buffer.
If anything could create a VGA output, it would probably be cpld or even fpga based.
By the way, there is a cpld hybrid zeddy, zx80 and Jupiter ace from holmatic in the German forum.
But without VGA (up to now).

[KnightFire]

Knew of the ax81, tried to contact the creator a year or so ago without success; I've a request of him. Would his direct driving of a 320x240 LCD display be useful for hires?
Alas I can't read CZ, nor German; and some of the sites just won't work with the online translators. Martin's site translates quite well thou.

[Paul]

PS
Is there any info on the different ZX80 mobo issues?

I would be very interested in any information about other issues.
I only know owners of issue 3 , divided in Kit and ready built.
There are different cases, some thicker were injection moulded, earlier models were thinner ABS that had been heated and pressed (how is this called in English?).
I have a zx80 keyboard that is not shiny, most were shiny though.
Some late models were without sockets, but all issue 3.
Having a different issue could increase its price significantly.
Any info is welcome. This summer I am going to start editing a wiki that was supplied by some German friends.
So any info is welcome, especially copies of prints and links to informations.
Please pm those to me.
I will try to have my wiki pages in English and German.
Kind regards
Paul.

[Lee Hart]

Hello to all,

I apologize for the long pause! KnightFire "woke me up" with a private email to see how things were going on my ZX80 board. The rev.A boards worked, but had a few problems I wanted to resolve before ordering more (keyboard layout, shift key operation, and video output). I set it aside to work on other projects until I had time to fix it properly.

Then Life got in the way. I got distracted by other things, and it's taken a while to get back to it! (If you're interested, you can see one of the distractions at http://www.sunrise-ev.com).

I have fixed the keyboard layout. It now accepts either RWAP's ZX80 membrane overlay, or individual tactile switches. I changed the keyboard pullup resistors from 47k to 10k, and the input chip from a 74HC244 to a 74LS244. That seems to have fixed the intermittent SHIFT key problem. (Note that the real cause is that the Sinclair design does not generate a proper logic low level on U10, the keyboard input IC).

I was working on the video when I set it aside. I am building a ZX81 adapter for it, that plugs into the expansion connector. It *almost* works! I am going to look at it again after my long "vacation" and see if I can resolve the issues.

If all goes well, I should be able to make another batch of these boards. Is anyone still interested?

[Paul]

Hello Lee
Nice to hear from you!
There is definitely still interest in your zx80 pcb's
I am glad you did not completely retired.