Sinclair ZX80 / ZX81 / Z88 Forums

I built the replica on the new PCBs and found small problem that I did not notice during the prototpe phase. It required just small almost invisible cut so I repaired all PCBs I will ship tomorrow (more info on my site http://www.8bity.cz/?p=380 ). The replica works as expected. http://www.8bity.cz/...

Hi all, thank you. I sent reply to all who sent me PMs. If you do not receive it, you can contact me at http://www.8bity.cz/wp-content/uploads/2011/04/email_martin_img_thumb7.gif . The PCBs are unpopulated and I sell them for production cost. I do not make it for profit. I built my first replica on ...

Hi, I have recreated a replica of ZX80 using Grante Searle's foil patterns, which I repaired (therer were 2 small errors) and I created the drill data and white silkscreen, so the PCBs are drilled, both sides tin-plated and connected with vias. Almost like an original ZX80. I created small batch of ...

I took picture of all the rivets. There are two colours and two sizes. Small whites hold the case togethe, small blacks hold the keyboard to the bottom part of the case and bigger three hold the PCB to the bottom part of the case. Sorry that the measurments are handmade, but I was too lasy to redraw...

The PCB was made by http://www.apama.cz/ here in Brno (Czech Republic). I plan to produce more PCBs for small Czech community, but if enyone else is interested, just mail me to kiwisek@hotmail.com.

SOLVED! The problem was caused by disturbance/intererence on the keybord row lines which were not connected anywhere if no key was pressed.I found that R13-R17 were not connected to the +5V on Grant's PCB. The other problem was that 47k is too much. I think about 10k should be OK, but I tried even l...

I tried this with no jack connected into EAR connector and the behaviour is the same. It returns immediately after NewLine. And the most strange is that original ZX80 does the same I am lost. Any other ideas before I will try logic analyzer?

Regards

Martin

Yes, I have the original ZX80 and the most strange is that it behaves the same way :-( It returns immediately after NewLine, no wait for any signal. I tried it with iPhone, not cassette recorder, is it different? I will have to look at LOAD routines, but I thought it just checks the keyboard for bre...

Hello, I have built a replica of ZX80 using Grant Searle PCB foils (I just created the drill data to make vias connect both layers of PCB as needed without soldering vias). I had to repair one mistake in Grant's work on /MREQ to make it work. Everything is working as expected with one exception. I c...