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The final step, the 1088XE. Version 2.0(This one works!) By Scott Peterson, June 1986.

Well, this is it for me, the last installment on the 130XE. I have not built this mother, but one has been built and tested by another person in Mass., and it works!! This doc assumes you have already 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.
Small piece of PC board.
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Note: On the 74 series, you can sub them with 74LS series chips, they use less power...

Tools;
Nothing fancy, a fine tip soldering iron, screwdriver, needle nose pliers, 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 and 5. 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. Run a jumper from the 7404 pin 2 to the 7432 pin 4. 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 (you might want to piggy back the 256K DRAM's prior to mounting them on-top of the 64K DRAM's). 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. Last but not least, install a jumper to pin one of each of the left bank of ram-chips, just like you did in the 576k mod to the bank on the right. After doing this run the jumper to any pin one of the right bank, what you should wind up with is a common connection to every pin one of both banks of ram-chips.

Your done!!!
Sorry, as of right now I know of no software to run on this (maybe Mydos 4.2? or Top-Dos 1.5+). I will provide a table for the control numbers, ect.

-------------------------------------
Bank# Control# Hex#
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1 1 1
2 3 3
3 5 5
4 7 7
5 9 9
6 11 B
7 13 D
8 15 F
9 33 21
10 35 23
11 37 25
12 39 27
13 41 29
14 43 2B
15 45 2D
16 47 2F
17 65 41
18 67 43
19 69 45
20 71 47
21 73 49
22 75 4B
23 77 4D
24 79 4F
25 97 61
26 99 63
27 101 65
28 103 67
29 105 69
30 107 6B
31 109 6D
32 111 6F
33 129 81
34 131 83
35 133 85
36 135 87
37 137 89
38 139 8B
39 141 8D
40 143 8F
41 161 A1
42 163 A3
43 165 A5
44 167 A7
45 169 A9
46 171 AB
47 173 AD
48 175 AF
49 193 C1
50 195 C3
51 197 C5
52 199 C7
53 201 C9
54 203 CB
55 205 CD
56 207 CF
57 225 E1
58 227 E3
59 229 E5
60 231 E7
61 233 E9
62 235 EB
63 237 ED
64 239 EF
-------------------------------------

That's all of them, 64 16K banks for a total of 1,024,000 bytes extended ram and 64,000 bytes of 'normal'(?) ram. I have a tester for this one but that's it for right now. Like I said earlier, There is a working model, It was built by Dennis Porter of Mass. His many long distance phone calls made this work.

Good Luck
Scott

P.S. 2 meg is very, very possible. You just need wwuunnn more control line. This would have to be bit 0 of the PIA, but you would lose the switch-able O.S. Its up to you guys from here, that's funny, the 1040 ST only has 1,024,000 bytes of ram.