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Build yourself a 128k Ram Card

Ok let's talk about how using these files to build a 128k ramcard for your HP48.

At first a warning. It is not easy to build a ramcard for the HP. I give you absolutly no waranty!!!

The best way is to install a unix and get the wonderfull program PCB from Thomas Nau. (look at pluto.medizin.uni-ulm.de) Then you can use the 'hp-ramcard' File and forgot the other things.

For those of you which are really poor DOS or WIN user is the rest.

1. Take the file HP2.PS and print it with a good laserprinter on transparent paper.
2. Make a single side circuit board with it. (use an epoxy board!)
3. Saw a hole in the board for Ramchip. The chip must lay upside down in the hole with his legs on the pads. You can read the partnumber from the chip on the side of the pcb where are _no_ copper lines. But don't solder it now!
4. Saw the board at the copper line around the board. But don't saw the copper line away!
5. Remove the copper line at the bus-area with a knife.
6. Slanting the board at the bus, so it is easier to put it in the HP.
7. Test the _empty_ card at the HP for good accuracy in fitting. Do some finetuning.
8. Take an electric drill and a little diamond rotary grinder. Look at place for the batterie. There must be a hollow for the batterie. Without a hollow the card is to thick!
9. Saw a hole for the microswitch.
10. Perhaps it is necessary to make some hollows for the diodes and the capacitor.
11. Glue a peace of epoxy on the upper-backside. It makes it easier to remove the card out of the HP.
12. Gild the bus with gold if you can do it! Without this I had have some problem after a year!
13. Solder the parts from the partlist. Have a look at HP1.PS and HP.GIF to find the right places.
14. Make the red bridges (HP3.PS) with very thin isolated wire.
15. >At least, connect the batterie.

I've done it, and it worked fine! Here is the result:

Good luck!

Stéphane Grundschober