Sinclair ZX80 / ZX81 / Z88 Forums

Hi,
my clone is done ... now I'm working on expansions - first is a zonx. This is a video of my first ZonX version on a breadboard https://www.youtube.com/watch?v=Kemn_Q3tHYs


Best,
Augusto Baffa

Hi there,

Welcome to the club!
My first computer was a Tk82c also ... I'm from Rio de Janeiro and have just assembled a clone from scratch

best,
Augusto Baffa

This is beautiful! Could u upload the eagle files?

Well... I've tested the logic and I bought it from a trusted store but I'm not entirely sure

but after my adjusts it's working very well... this is my final version with slow circuit and zx81 8k rom

First, change all capacitors.

So... after these years... Did u get it working?

mrtinb wrote: ↑Fri May 04, 2018 7:48 pm That would be 7400-chips. It's a proof og concept to connect to other hardware. Let's see what time will bring.

I've found an issue in the project. There is an high pass RC filter after IC8 PIN9 that creates a pulse signal to IC11 PIN2 (LS7400 NAND) and IC16 PIN9 (74LS10 3-NAND). error.png That differential RC Pulse circuit works correctly to IC 16 feeds IC9 S/L PIN 1 but is not working on IC 11 to activate t...

Hello, my name is Augusto Baffa and I'm from Rio. My first computer was a TK-82C (brazilian clone of ZX81 by microdigital). My father bought in 1982(when I was 2 years old) and give to me when I was 9. Of course I was allowed to play with it but only under supervision. When I was nine he encouraged ...

Hi folks, I am building a ZX80 following the ZX80 project on the Grant Searle website and it is working, but the screen is inverted. WhatsApp Image 2021-02-06 at 00.45.49.jpeg WhatsApp Image 2021-02-14 at 11.28.12.jpeg If I remove the R25(470) I get a "normal" inverse image but the characters are be...

I couldn't find Charlie Ingley on the member list. Could u tell me his username? He introduces himself here ;) Mark There is a TK90X ULA developed by Victor Trucco and Fabio Belavenuto in 2012 using a CPLD (code versions for Xilinx and Altera). TK90X is a brazilian clone of ZX Spectrum and uses a d...