Thanks for looking at our Sinclair ZX81 computer – Refurbished and Upgraded to 32K RAM and HRG (Hi Res Graphics) Ready!
Original Polys but no outer cover.
We’ve performed the following work on this little beast:
- Replaced the 5 volt regulator with a new 7805CV, The old regulator was far too noisy and on its way out.
- Added a 100uF capacitor to the output of the regulator to remove noise – helps with artifacting on the screen.
- Replaced the paltry 1K memory with a 32K SRAM chip using a custom PCB – now the ZX-81 has 32K RAM internally! No more RAM pack wobble – and you get to use hires graphics (HRG) as the custom PCB also enables that. You can also disable the HRG8 function with the new revision of our PCB by removing the white jumper.
- All electrolytic capacitors have been changed to make sure that the ZX-81 has a stable power supply.
- The insides of the RF modulator have been swapped out for another custom PCB that gives the ZX-81 excellent composite video output and produces the needed back porch to allow the ZX81 to give a crystal clear picture on modern TV’s – and it uses the same socket as the RF modulator used to so that we don’t have to modify the case at all.
- Comes with its original Sinclair ZX-81 power supply. The power supply has also had its electrolytic capacitors changed.
All in all, this is a well upgraded, refurbished Sinclair ZX-81 computer with a case which is very tidy.
The little man even has new rubber feet to replace the old stinky shoes he used to have!
If you have any questions about this Sinclair ZX81 computer or any of the other computers or modifications on our site then please do not hesitate to contact us.
Also available on eBay – http://ebay.us/4AbuBN?cmpnId=5338273189