How to open 5155?

Tony Duell ard at
Sun Mar 19 13:15:38 CST 2006

> Tony Duell wrote:
> > Undo the 6 screws on the front of the machine (2 
> > rows of 3, pretty obvious when you look at it). 
> Not if you've never taken off the keyboard before (/me smacks forehead)

Ah... Actually, I think the keyboard was supposed to be user-removable. 
You could unclip it when using the machine so you could put it in a 
convenient location.

> > Slot 2 is a 
> > full-length slot
> Looks like my last remaining Plus Hardcard 20 is going to find a home 
> (hope it still works).  Or, I could try to find an IDE adapter and then 
> a CF-to-IDE adapter on top of that...

I feel iike the proverbial donkey who starves between 2 bales of straw. I 
can't decide what to put in slot 2 of my 5155. Candidates are the 
expansion unit interface (which would give me a lot more slots, but ruin 
the portability), a data acquistion card, a GPIB card, or a Transputer 
host interface... All would be rather nice in a portable machine.

> > One thing that is worth doing is the 640K mod. Being a normal XT 
> > motherboard, you can put 41256s in banks 0 and 1, 4164s in banks 2 and 3, 
> > a 74S158 (or 74F158) in the empty DIL socket at the front of the board, 
> > and solder a jumper between pads E1 and E2. Set the DIP swtiches for 256K 
> > (really, all 4 banks used), and you dnn't need any memory expansion cards...
> Good to know, thanks!  You're always a help.


What I forgot to mention last night tis that while the modification is 
easy, geting the motherboard out is not. Obviously you have to remvoe all 
the expansion cards, unplug the power cables and the keyboard DIN plug at 
the back. And then you have to remove the floppy drives (they come out 
backwards IIRC). since you get to one of the fixing screws _though_ the 
floppy drive aperture. The board then slides out towards the right hand 
side of the machine.

I can look up the exact procedure if you have problems.


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