Manufacturer:Private project of a group of Microtel engineers
Model:Portable using a Xerox-820 mainboard
Serial Number:-
Year of Manufacture: Logic board: IC date codes early-mid 1981
Disk drive: IC date codes 80nn, DIP switches 8235
Power supply: latest IC date code 8147
Date of Receipt:~ 2003
Source:NS
State upon Receipt: Excellent physical condition. Second 820 mainboard included.


Date: 2009 Dec
Symptoms: Powered up, screen filled with @ and P except at beginning where monitor message is displayed, which is likewise scrambled. Would appear to be video-memory problems.
Analysis: Second 820 board swapped in to check it, display good, monitor comes up "XEROX 820 VER. 2.0".
Solution: Two 9114's for high-order-bits of video memory on first board replaced with TMS2114-45NL, sockets installed. Video problem fixed: reset/power-up brings up monitor "XEROX 820 VER. 2.0". "a" command with boot disk boots to "Big Board CP/M 60K VERSION 2.2.1".


Date: 2013 Feb
Symptoms: Powered up. Some keys not functional, correlates to keyboard data bit 0.
Solution: Keyboard opened and connector exercised, OK, now functional, may have been connector pin cleaned by insertions. Now boots to CP/M, DIR works, some other commands hang.


Date: ~ 2013
Procedure: Transferred to RF.


Date: 2021
Procedure: Transferred to UVic.


Date: 2022 Jul
Symptoms: Some keys again not functional, appears to be same problem of 2013 Feb.
Analysis: Again, OK after keyboard has been opened. Signal levels observed on data lines from keyboard onto main board: appear OK, nothing unusual or distinguishing.
Problem appears again a few days later. Signal for LSB bit now middling at Z5.1,2 input: 2V L ~ 3V H. Connection through IC socket at Z12.2 (output from keyboard scanner) poor, varying up to > 60 ohms.
Solution: Z12 reseated, OK. Socket is SCANBE, side-contact pins.