After nearly 40 years in storage, I have got a ZX81 to show my son how we used to program for fun when I was a lot younger. We have found out how far things have progressed since then.
Our ZX81 is an Issue 1 with an early version ULA, and we have been trying to make it work with 21st Century Tech by;
Changing the RF Output to Composite with one Transistor and two Resistors to allow it to work on a modern TV.
Changing the RC Network to try and Save to a PC Sound Card as we don't have a Cassette Reorder. But this still did not work.
Changing the 5 Volt Regulator to a DC-DC Rgulator
Replacing the RF Modulator and Transistor modification with a full Back Porch Board.
Add a three Resistor ZX-Wespi ESP32 Board, now with zx-iot-mi V0.2.2.0 software on it.
Change Internal RAM from 1K to 16K using 32K RAM Chip and linking LK2
But the ZX-Wespi software will not run after typing LOAD "" as can be seen in the video.
Although it did run once after it was left switched on for a couple of minutes. But the option "Save" did not do anything. Nor could we enter "SYS" or "HELP", as we could only get to "SAVE" or "GOSUB" respectively.
Could it be due to the early issue Version of ULA that we have? Does it need a newer version? Is there something else we can check?
ZX-Wespi help needed
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ZX-Wespi help needed
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Re: ZX-Wespi help needed
I don't know, why it is not working for you.
I think you need to ask for help in the topic in the German forum:
https://forum.tlienhard.com/phpBB3/viewtopic.php?t=3360
I think you need to ask for help in the topic in the German forum:
https://forum.tlienhard.com/phpBB3/viewtopic.php?t=3360
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Re: ZX-Wespi help needed
Does your zeddy have the early maths bugged ROM with the PRINT SQR error?
I had one like that and could not get the Wespi to work. It had a fairly early ULA (date code 8112) and worked once I replaced the ROM.
I had one like that and could not get the Wespi to work. It had a fairly early ULA (date code 8112) and worked once I replaced the ROM.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Re: ZX-Wespi help needed
Did you change the RC network for loading as well?
You better return to the original values for load and save.
Which ULA Version have you got?
184 and 210 are known as working.
I'm not sure we tried the earlier type (lower than 184, can't remember right now)
You better return to the original values for load and save.
Which ULA Version have you got?
184 and 210 are known as working.
I'm not sure we tried the earlier type (lower than 184, can't remember right now)
In theory, there is no difference between theory and practice. But, in practice, there is.
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- Joined: Thu Jun 09, 2022 12:11 am
Re: ZX-Wespi help needed
Thank you all for your replies.
It's all a bit new (again) after all these years, and a steep learning curve. But a fun challenge for my son and I. However I must admit that I was pleasantly surprised it worked from day one when we first powered it on. All the other bits like not working on a modern TV, or no Cassette Recorder has been very interesting finding out how to resolve.
We will check out the link to the German Forum to see what we can find out from there. As for the ULA and ROM versions we will check what is which. I think the ULA was either 154 or 184?
But will get back to you with the details. Plus yes we changed the RC Network back to the original.
I will also double check our wiring and solder joints. It is odd though how it got to the Splash Screen once, after some minutes, when we forgot to power it off? Or could there be some interference being picked up by our wiring? Our cables to the ESP32 are all on the Component side of PCB, and not screened. We'll let you know any developments.
It's all a bit new (again) after all these years, and a steep learning curve. But a fun challenge for my son and I. However I must admit that I was pleasantly surprised it worked from day one when we first powered it on. All the other bits like not working on a modern TV, or no Cassette Recorder has been very interesting finding out how to resolve.
We will check out the link to the German Forum to see what we can find out from there. As for the ULA and ROM versions we will check what is which. I think the ULA was either 154 or 184?
But will get back to you with the details. Plus yes we changed the RC Network back to the original.
I will also double check our wiring and solder joints. It is odd though how it got to the Splash Screen once, after some minutes, when we forgot to power it off? Or could there be some interference being picked up by our wiring? Our cables to the ESP32 are all on the Component side of PCB, and not screened. We'll let you know any developments.
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- Joined: Thu Jun 09, 2022 12:11 am
Re: ZX-Wespi help needed
We have a ULA Type ULA2C184E and the ROM is a P22389 D23644C 649
If that means anything to someone?
If that means anything to someone?
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- Joined: Sat Nov 26, 2016 2:42 am
Re: ZX-Wespi help needed
It means both the ROM and ULA types are fine to work with a Wespi.
Here is one I fitted to those types recently:
Here is one I fitted to those types recently:
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
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- Posts: 4
- Joined: Thu Jun 09, 2022 12:11 am
Re: ZX-Wespi help needed
I think that we will need to experiment with moving the wires and the position of the ESP32 Board.
Ours came with Header Pins that make it taller, and that is why the Board is mounted 90 degrees differently to yours. Plus our wires are soldered to the Component Side of the ZX81. So we will solder them to the Underside instead. It could be that there is some interference between the Boards?
The Back Porch Board is fitted inside the RF Modulator Can, and the RF Board has been removed. Also we used an Electrolytic Capacitor instead of a Tantulum, but this shouldn't be causing our issue. It's just larger in size.
We have already cut back the Keyboard Flexi Cable due to a break in the Foil, but the Flexi is already showing signs of more cracking. So I am nervous of making too many more adjustments inside before it breaks again. Although I had bought a spare Replacement Keyboard when I thought that it was "worn out" before I found the broken Foil. So that could be one more thing the ZX81 requires.
Ours came with Header Pins that make it taller, and that is why the Board is mounted 90 degrees differently to yours. Plus our wires are soldered to the Component Side of the ZX81. So we will solder them to the Underside instead. It could be that there is some interference between the Boards?
The Back Porch Board is fitted inside the RF Modulator Can, and the RF Board has been removed. Also we used an Electrolytic Capacitor instead of a Tantulum, but this shouldn't be causing our issue. It's just larger in size.
We have already cut back the Keyboard Flexi Cable due to a break in the Foil, but the Flexi is already showing signs of more cracking. So I am nervous of making too many more adjustments inside before it breaks again. Although I had bought a spare Replacement Keyboard when I thought that it was "worn out" before I found the broken Foil. So that could be one more thing the ZX81 requires.