ZX81 Part 2 – Upgrading the on board memory from 1K to 16K
ZX81 Repair and upgrade
Part 2 – Upgrading the on board memory from 1K to 16K
00:00 Introduction
02:13 removing the old chip
04:22 Repairing a faulty circuit board trace
08:48 Installing the wrong chip socket
18:15 This is where I realise my mistake
19:40 Replacing the wrong socket with the correct one
24:50 Bending the chip pins for the correct connections
29:00 Testing and photos
4-part trilogy* upgrading and repairing a ZX81
Part 1 – Replacing the TV modulator
Part 2 – Upgrading the on board memory from 1K to 16K
Part 3 – Replacing the faulty keyboard
Part 4 – Recapping and voltage regulator
EBay TV Composite Video (TV Modulator)
https://ebay.us/nJB9rY
EBay Replacement 16k RAM Chip
https://ebay.us/IPAQIy
EBay Replacement Keyboard
https://ebay.us/bZXQ1m
ZX-81 Components
https://www.retroleum.co.uk/sinclair-...
You can find an excellent ZX81 emulator here
http://www.zx81stuff.org.uk/zx81/jtyo...
You can see early PCs at these two computer museums:
Bletchley Park: https://www.tnmoc.org/
Cambridge: http://www.computinghistory.org.uk/
*A trilogy in four parts.
https://en.wikipedia.org/wiki/The_Hit...