130xe to 1088kxe Upgrade

Well, this is it for me, the last installment on the 130XE. I have not built this mother, but the theory behind it has been built and tested. This doc assumes you have all ready built and tested a 576K 130XE. to finish it you will need the following parts;

Quanity part no. description.
16 41256-15 256K DRAM'S
1 7432 quad OR gate
1 7404 quad invert buff.
2 33 omh resistors.
1 Small piece of PC board.

Note: On the 74 series, you can sub them with 74LS series chips, they use less power...

Nothing fancy, a fine tip soldering iron and some fine wire, ect. Mount the 7404 and the 7432 on a small PC board(1in. X 2in.) connect together pin 14 on the 7432 and pin 14 on the 7404 with a length of fine wire. This is the +5v supply to the chips, connect it to pin 14 of any 14 pin chip in the 130XE or pin 16 of any 16 pin chip in the 130XE. Next connect a lenght of wire to pin 7 of the 7432 and pin 7 of the 7404, this is ground for the two chips, connect it to pin 7 of any 14 pin chip in the 130XE or pin 8 of and 16 pin chip. Next, take U23(U23) out of the socket and bend up pin 17, reinsert it in the socket. Solder a piece of wire to pin 17 U23, and connect it to the 7432 pins 2 and5. Next connect a wire to pin 14 on U23(PIA) run it to pin 1 on the 7404 and pin 1 on the 7432. Now connect a wire from the 7432 pin 6 to pin 17 of the socket U23 is in. Find the 74LS138 you piggy backed to the mother board when doing the 576k mod, remove the jumper from pins 1 and 16. solder a wire from pin 3 of
the 7432 on the PC board to pin 1 of the piggybacked 74LS138. Put some double backed tape on the PC board and stick it somewhere on the mother board of the 130XE. RAM-CHIP installation (lots of them!) Take the
16 new ram chips and cut pin 15 on all of them in half so only the 'fat' part is left. Now, you have to piggy back them on-top of the 64K drams (the left-most row of chips). Solder in 8 of them, connecting all pins except pin 15, then connect a jumper to pin 15 of each new ram chip. Make sure you have about a foot left over. Solder in the next 8 doing the same thing. When you get done you should have 2 new rows of 256k DRAM's solder in on-top of the 64K DRAM's, with a 2 wires, one connected to all the pin 15's of the middle row and another connected to all the
pin 15's of the top row. Take one wire and go out a few inches and install a 33 ohm resistor in-line, cover with heat shrink tubing and do the same to the other wire. Connect one wire to pin 15 of the 74LS138 and the other to pin 13 of the 74LS138. Your done!!! Sorry, as of right now I know of no software to run on this. I release this doc file with out testing it. I have built the small circuit on the PC board and connected it in a 576K 130XE and used it to move the memory instead of the basic control bit, so I know it works, this little circuit works in both the 800xl or 130XE if you have something you would like to use bit 7(self test bit) for. If you have constructed a 320XE mod and would like to use bit 7 instead of bit 5, this is a good way to do it. A warning though, you will regain your antic enhanced mode but software written for the original 320XE mod will not run on it after you do it.

If you are trying to figure out your memory control bits here's a cheat sheet.
Decimal 128 64 32 16 8 4 2 1
Control bit 7 6 5 4 3 2 1 0

Just find you control bits and add them up to figure out the decimal control number. When you get done you should have in one switch position a 130XE with 320K,built in basic and antic enhanced mode. In the other position you lose antic enhanced mode, internal basic but you have 1088K of memory, 64 banks of 16K. By the way typing BYE will still throw you into the self test mode (bit 7 still works). If anyone completes' this monster,
please call my BBS at (408)-384-3906,c or leave me a message at compuserve.

Good Luck


About ILS  -  Contact us  -  Report Web Issues