ZX80 Core - new ZX80 motherboards

[PokeMon]

Did you set jumper J98 correct ?
This is for the video polarity.
Might be a cold soldering there in the near.

And please check C9 - should be a 68pF capacitor.
This is a little bit responsable for the correct video timing - shift register control together with R2 (470R).

And J100 and R100 is important - this is new on the V11 revision and control the usage of EPROM or EEPROM.
For example, could work without setting J100 but not very properly as it could be very sensitive for static electricity without.

[blittled]

I have the 32K EEPPROM and I have J100 set to middle and right pins but I left out R100 since I thought it was only for EPROMS like the 27C256. Do I need R100?

Edit: I just reread the posts discussing R100 and I see it is required. I'll put it in and see if it works.

[PokeMon]

Yes - it is necessary as it leaves a pin open, which is an address line of EEPROM and may be influenced through electromagnetic fields.
I had an effect prior which gave wrong pixels from the character generator when I moved a finger near the EEPROM which disappeared when removing the finger.
Sometimes complete system hang when getting to close with the finger (like an antenna).

[blittled]

i added the resistor R100 and resoldered the pins of all the ICs involved in the video generation and it came up 100%. I also loaded Mazogs through the ear input with no problem. Just one more question if I may. In inverted video mode does the top and bottom margins still appear white? Now for the fun of soldering the tactile switches

[PokeMon]

Just one more question if I may. In inverted video mode does the top and bottom margins still appear white?

Well, if you use the NMI generator board ZX80NMIX - the answer is yes in SLOW mode. You can enter FAST mode and get a full black screen. The reason is, I followed here a hint of Grant Searle to avoid disturbing pixels on screen caused through I/O programming in SLOW mode on the ZX80. So there is a gate which let the video data through only during video generation not in program mode (the blank lines above and below the screen contents).

Another possibility would be to use the external module ZX8-CCB on J94 instead of the onboard video. So just remove R80 and R89 on solder side, use the 4x2 pin header on J94 and put the ZX8-CCB module on it and use the invert picture jumper on that module rather than inverting the video signal on J98.

[lusciousthelock]

Hi PokeMon, really lovely kit! I recieved mine on Friday and nearly finished building her (been a busy weekend) but Just wanted to check that I do still need to do the mods on R4 and the resistor added to pin 1? Reason I ask as these are detailed in an older 2013 version of your manual but not in the shorter 2014 version?

Also, how are the cases coming?

[PokeMon]

No - these mods are not any more necessary on the V11 board (with the premounted SMD chip on the backside).
They have been fixed.

Cases will be produced later this week - available in about 2 weeks I think.
I will post here more information tomorrow.

[yerzmyey]

Pokemon, it wouldn't kill you to answer the PM.

Ah well.

[PokeMon]

I did answer your enquiry already at 18th of march.
I reposted it now.

[yerzmyey]

Pokemon:

Yes, the idea with PDF could be very good, I will look at it now!