*** M E M O R U M ***

Hi guys, I've acquired an MTX500 which booted to a white screen when I first turned it on. It had an expansion card fitted (pictured below) - I removed this and the machine now boots fine.

So - what is the board, a RAM expansion? And any ideas why it might cause such an issue? Should it have more chips than it has perhaps, or are the empty sockets just there to add more RAM?

Thanks,
Andy

Hi Andy,

The board is the (relatively common) 32k expansion board. Very often added to an MTX500 to make a 64k machine. The empty sockets are normally unpopulated but were used on an RS128 to hold the additional 64k.

In your case, it does sound like it has a fault though. The only socketed chip is the PAL memory decoder, you might try making sure that it is seated correctly in the socket.

Regards
Dave

Thanks Dave, that worked! A PEEK of 64122 shows the expected 1 so I appear to have a fully working 64k now

Great!

glad you're sorted.

Of course, I will take all the credit for this highly technical repair

It is worth noting though, that the connections to internal boards are prone to problems, the cheap "solder" contacts don't perform very well. You might find that you have to break/remake the connection between the RAM board and the motherboard every so often, ideally, giving the connector a little clean at the same time. Memotech were aware of the problems, and many expansion boards (including my original "MTX512") have the expansion board soldered to the motherboard.


regards
Dave