Mike's PCjr Page

Before I drag out the logic analyzer....!

My test unit I have set up:
Decided to test a new PS2 Dongle last night, powered up the Jr and the screen mem test counted to ( 004 KB )
then just stopped.... hmmmmm
reset the internal 64K mem board, even swapped it out just in case..
I know this is counting the lower 64K mem that is located ON- the system board.

I decided to strip down the system to just the bare 64K with power supply, no Floppy controller or side cars...
Still counted to ( 004 KB ) and stuck there...

I am going to assume it is the on-board 64K mem chips with the issue or associated ckty, but what bothered
me is that it did not even 'error' out.... just stuck..
so before I dive in I wanted to know if anyone else had run across this issue ..
thanks
Chuck

I may have discovered the issue..
On the MB the first ROM had an extender, I had noticed this, but dismissed it earlier when updating the board with sockets for the TandyMod and Sprint...

Took out the sockets and found a Dallas Clock chip nested inbetween..

So I have never seen this , assumed , Clock solution for the Jr.
Has anyone seen this and is there software support for it ?

I am assuming there is a battery nested in here somewhere, I have not taken it apart, until I get some feedback as to what the Heck this is...

Chuck

The Dallas Chip you have there is documented here: http://www.brutman.com/PCjr/DS1216E.html

The software is there too.

You can remove it to be sure but I doubt that it is your problem unless it has been damaged. In theory it has the ability to alter what the ROM returns. In fact, that is how it works. But it only does that when you "wiggle" the address lines the correct way first. A dead battery on it does not matter.

The DRAMs on the board are not parity checked; it's more likely that you have a bad DRAM.

Agree, I am going to keep an eye on this MB and since I have it as a test set
it should act up again when I use it.

Plenty of chip on ebay.....so should not be a problem....but Sockets are going in !