Spectrum Computing

I am moving home, so some of my gadgets must go. I have listed the following: 1. Romantic Robot Videoface replica: https://www.ebay.co.uk/itm/266255840593 2. ZX-BTaudio interface: https://www.ebay.co.uk/itm/266255831011 3. ZX Nuvo 128K (issue 1) - partially assembled: https://www.ebay.co.uk/itm/2662...

@KWF do you mean TR1 and TR2? Yes indeed. My mistake, just corrected. The existing ZTX313 are likely to be fine. They rarely cause problems. So check/replace the capacitors first. Well, if you are on the Perfect Video Signal Quest it might be worth replacing noisy transistors with better ones. ;)

Give a good cleaning of the RCA connector with a wet sandpaper like 1000 grid. An oxidation of the RCA to be removed. You can also try following: - replace caps in 12V line. The most critical are C44 and C45 (100uF each). Good quality low ESR caps will help. - replace TR1 and TR2 if they are ZTX313 ...

You are missing the point, because this one is suitable for line/aux inputs and gives low level output signal. ZX Spectrum EAR input needs a bit of power.

It would be straight forward if you selected a different BT audio module than MH-M18. There are off shelves modules with embedded audio amplifiers.

I've checked Sizif512 schematic and the BT module audio output is connected to the Tape In input, biased there and then amplified/converted to square wave using NOT gates (74HCU04 type fed off 3.3V line), and finally wired to 3.3V CPLD. In ZX Max 128, the audio output of BT module might wired in sim...

I cannot find any reference to the BT module in ZX Max 128K. I am not familiar with ZX Sizif and how the BT module is connected there, but there is 3.3V TTL logic instead of 5V.

MH-M18 modules got weak audio outputs, the signal swing is approx. 1V only and you need an amplifier. Have look here: https://forum.tlienhard.com/phpBB3/viewtopic.php?t=3847 and here: https://www.youtube.com/watch?v=rLYKKHdo0hs I've designed and built an external module that can be connected to any ...

F/W v.6,85 is the only one that allows programming all supported GAL types correctly.

yeah, counting DIP switches from the left:
S1 - DivMMC Flash ROM OFF / ON

The others are as shown in the photo in.the post above.

If you were interested in building ZX Spectrum IssueOne replica, I would be able to help. Drop me a PM.

If your ULA is deaf there is a way around the issue. You can add the audio input using one transistor and a 3-state buffer connected directly to CPU data bus. If you go one step further you can also add Bluetooth audio module and it work like a charm, loading software directly from a mobile.

Congratulations with the purchase. Personally I was not able to justify spending silly money on Issue One, so I cloned it a few years ago. It was a challenge because I had to do all tracks manually with no access to real one and using photos available on various websites and with a help of a few goo...

ZX Spectrum standard is BT631W not A.
Have a look here: https://www.britishtelephones.com/documents/plug431.pdf

And here: https://zxnet.co.uk/spectrum/btconnectors/

ZXSP + ZASM: https://k1.spdns.de/Develop/Projects/zx ... ributions/

Hi David, Thanks for the message. I'd love to hear more about what you made, see some pictures and hear more about your plans. Please visit my GitHub, the link in the footnote. There are some of my retro works. A bit more is on my youtube channel , but not much. My plans are fluid, however now I am ...

Hi All, I recreated Videoface (VF) digitiser for ZX Spectrum and it works as it should. However it is slow (approx. 3 frames/sec) and quality of captured images could be better. From the other hand, VF is easy to build, but don’t trust in the schematic diagram available on the net. I’ve read about a...

Hi All, I have been back to 8-bits for a few year as mainly reader on other Speccy forums. I am not a Facebook fan, so I don't know what is going on there in retro-world. When I was a teenager my parents bought me Timex Computer 2048 and I played games and wrote a few BASIC programs back then. Then ...