Russian PCB ZX80 clone problem

Discussions about Sinclair ZX80 and ZX81 Hardware
crrush
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Joined: Fri Jul 26, 2019 10:38 pm

Re: Russian PCB ZX80 clone problem

Post by crrush »

Erm wrote:
Sun Nov 17, 2019 6:22 pm
I'm following this more intently now.
Sure, I will inform you of my progress. However, let's deal with this situation technically wise. Let's also assume the ROM is okay now, but we have the very same picture.
The TV picture is generated only if the CPU (at least starts) reads ROM and may write to RAM, the later is somewhat being controlled by 8 bit IC5. Right? IC 20 is doing some clock job and address video signal, so it is rather good, its clock is ok (since CPU is working). Assuming that I may conclude that it is IC 21 to blame for the bad picture.
Also, IC 18 and 19 are responsible for synch generation. Also, IC 15 is mixing M1 cycles signal with synch, so it also falls into suspicion.
I am moving in right direction?

crrush
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Re: Russian PCB ZX80 clone problem

Post by crrush »

Meanwhile, empty EPROM has just been confirmed

crrush
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Re: Russian PCB ZX80 clone problem

Post by crrush »

Erm wrote:
Sun Nov 17, 2019 6:22 pm
I'm following this more intently now
Alright so I was able to finally start my "Russian PCB" clone, after flashing the ROM. The chip that comes with the kit is empty, so you will need to actually flash it.
After the boot it works, but there are some problems with keyboard and the picture. But it is a breakthrough!
https://www.youtube.com/watch?v=39oFULWiTd0

So for all of those who will build that kit from Ebay - do not forget about ROM, and the kit will start right away nicely.
And yes, looks like keyboard cc for shift key, as it prints "Clear" instead of "X"

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mrtinb
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Re: Russian PCB ZX80 clone problem

Post by mrtinb »

X is supposed to type CLEAR.

Look at the keyboard layout here:
https://da.wikipedia.org/wiki/ZX81#/med ... r_ZX81.jpg
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

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mrtinb
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Re: Russian PCB ZX80 clone problem

Post by mrtinb »

Read chapter 2 in the manual, and you will understand that you should never spell out commands on a ZX81.

http://www.worldofspectrum.org/ZX81BasicProgramming/
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

Moggy
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Re: Russian PCB ZX80 clone problem

Post by Moggy »

mrtinb wrote:
Thu Jan 30, 2020 4:21 pm
Read chapter 2 in the manual, and you will understand that you should never spell out commands on a ZX81.

http://www.worldofspectrum.org/ZX81BasicProgramming/
But you have to spell out some commands on a ZX80 which I think this thread is about unless I've missed something.

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1024MAK
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Re: Russian PCB ZX80 clone problem

Post by 1024MAK »

It may be a clone of a ZX80, in which case, the keyboard looks like this:
Image

Most BASIC key words use the ‘single’ keypress system, apart from some functions where they are entered letter by letter.

The ZX80 manual is here (hosted by World of Spectrum).

Ahh Moggy was wide awake and beat me to it :mrgreen:

Mark

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mrtinb
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Re: Russian PCB ZX80 clone problem

Post by mrtinb »

But even with the ZX80, pressing X gives CLEAR.
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

Moggy
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Re: Russian PCB ZX80 clone problem

Post by Moggy »

Now there's a first Mark!! :lol:

crrush
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Re: Russian PCB ZX80 clone problem

Post by crrush »

Well, that is even better, the keyboard works perfectly in that case then!
For some reason I though ZX Spectrum has all its BASIC command bind to keys, but if ZX 80 has the same concept, it is alright then

The next stop will be Jupiter Ace clone BTW

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