UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Computers


Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

Thread Tools
Old 12th May 2022, 11:05 am   #1
Join Date: May 2022
Location: Bilbao, Spain
Posts: 10
Default A curiosity: security flaw in Sharp PC-1430

The Sharp PC-1430 was a pocket computer programmable in BASIC. I got mine in 1986 and it still works. Mine even has RAM expanded to a whooping 4 KB (giving around 3 KB of usable RAM) by soldering a second SRAM chip on an empty position.

The thing is, I found a silly way to bypass the password protection at the cost of some RAM corruption.

One day, while I was bored, i filled the input buffer. And when it got full I hit "INS" like I was going to insert another character.

It should have ignored the keypress, but it really tried to insert and I saw an odd characer which wasn´t in the official character set accessible from the keyboard: A tilde (~).

Curious about that I kept pressing INS repeteadly while more tildes and other undocumented characters like aquare root, some greek letters, etc, appeared. It was obvious I was dumping memory.

At some point I kept pressing INS and suddenly I saw the password appearing on screen. Assuming that it had been replaced by the most frequent characters I saw (which was the tilde, probably a 0, I cleaned the input buffer and I gave the order:

PASS "~~~~~~~~"

And it worked. Password bypassed!

I guess it will work on other similar computers. I think the pocket TRS-80 was a rebranded Sharp?

Just thought you would find it amusing
borjamar is offline   Reply With Quote
Old 13th May 2022, 11:16 am   #2
Join Date: Oct 2010
Location: Melton Mowbray, Leicestershire, UK.
Posts: 147
Default Re: A curiosity: security flaw in Sharp PC-1430


I suppose you should tell Sharp and give them a chance to fix the problem ;-)

Good find. There are people in the retro computer community who will pick this up and run with it.


acollins22 is offline   Reply With Quote

Thread Tools

All times are GMT. The time now is 1:10 am.

All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at
Failure to heed this warning may result in death or serious injury to yourself and/or others.

Powered by vBulletin®
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.