by Scott Peterson
I have written the following documentation in such a manner that you can use it to help you keep track of your progress as you assemble this memory enhancement. Simply place a check in the space provided as you proceed. This will allow you to readily follow your progress, and pick back up where you left off if you should have to stop.
Once you have finished this upgrade you will then have in your possession an Atari 65XE with 320K of total ram. This is broken down into chunks of 64K of standard ram, and 265K of page mapped ram. This upgrade is 100% compatible with the previous 130XE/320K upgrade and therefore will run all programs that the earlier enhancement ran.
The Author nor this WEB Site claim any responsibility for any type of damages incurred by do this modification
The equipment you will need is:
A: A medium sized Phillips head screwdriver.
B: A very small jeweler's screwdriver with flat blade.
C: Soldering wick (recommend Chem-Wik .100 inch size), or vacuum desoldering
D: Soldering station (like Weller model WTCP), or LOW wattage soldering
pencil of the 15-25 watt variety.
E: Small pair of needle-nosed pliers.
F: #30 gauge wire (Jameco #130 BE)
G: Wire stripping tool for #30 gauge wire ("Clip and Strip" Jameco #CAS-130).
H: Heat shrink tubing or black electrical tape (tubing preferred).
I. Small pair of wire snippers.
J: Optional: Small carpet sample or blanket.
The parts you will need are:
A: Z1-------> 74LS158
B: Z2-------> CO25953 (Custom chip by Atari)
C: Z3-Z10---> 256K Ram chips #41256-150 (8 required)
D: R1,R2----> 33 ohm 1/4 watt resistors (2 required)
And here we go.................
1.___Place carpet sample or small blanket on a clean, uncluttered workspace
that is well lighted.
2.___Situate all tools and parts on one side of your workspace.
3.___OPTIONAL: Get a fresh cup of coffee!
4.___Place 65XE face down on carpet. Remove all screws holding cabinet
together. Turn unit over. Remove top of cabinet and lay it in a safe place.
5.___Gently pull upward with fingertips on mylar extending from keyboard and
remove it from its connector. Place this keyboard assembly with the top of
the cabinet. Place screws in a small container so they won't be misplaced.
6.___Take needle-nosed pliers and turn all twist tabs on metal shield so it
may be easily removed. Remove all screws from outer edges of PC Board and
then place screws in your container, and the top and bottom shields along
with the bottom of the cabinet should be placed with the rest of the 65xe
7.___Place all ICs in front of you and proceed with the following:
a.___Bend up pin number 15 on all 8 of the 41256 rams. Then snip off the thin
part of the leg so all you have left of pin 15 is the "stub" or fat portion.
Do this on all 8 rams.
b.___Bend up all pins with the exception of 8 and 16 on the 74LS158. Leave
the legs on 8 and 16 long, and snip the thin part off all other pins on this
c.___Bend up all pins with the exception of 8 and 16 on the CO25953. Leave
the legs on 8 and 16 long, and snip the thin part off all other pins on this
d.___Take both 33 ohm resistors and snip the leads so their is 1/4 of an inch
of lead left on either end of each of these resistors.
e.___Place these chips to one side, and position the 65XE motherboard in
front of you. Locate IC numbers U9 through U16. You will find them running
along the left side of the motherboard. Take a piece of tape or a small black
magic marker and place a small mark next to the IC that is labeled U12. You
see the wisdom of doing so later on in this documentation.
8.___Proceed to piggy-back ICs Z3 thru Z10 inclusive on top of ICs U8 thru
U15 inclusive. Please take your time and be sure that each chip is facing
the same direction as the integrated circuit below it. Do a good job
soldering so not only will this upgrade work well but also will be pleasing
to the eyes when you show it off to your admiring friends!
9.___Cut 7 small pieces of #30 gauge wire, and use these to connect all 8 of
the pin 15s of the piggy-backed rams.
10.___Gently turn the 65Xe motherboard over exposing the underside to your
trusty soldering iron. Cut 7 more small pieces of #30 gauge wire and then
proceed to jumper all the pin 1s of the rams. Cut another piece of #30 gauge
wire approximately one foot long and solder it to pin one also and then run
it through a convenient hole in the motherboard. Turn the motherboard back
up with parts side once again smiling up at you.
11.___Grasp the 74LS158 and proceed to piggy-back it on top of an IC on the
motherboard labeled U24 which you will find at the front right of your
computer. Make sure it is facing the same direction as the chip you are
placing it on top of and proceed to solder pin 1 of the 74LS158 to pin one
of U24. Next solder pin 16 of the 74LS158 to pin 16 of U24.
12.___Grasp the CO25953 IC and proceed to piggy-back this gem on top of U2.
U2 can be found approximately in the dead center of your 65XE motherboard.
Again, please make sure both chips are facing the same direction. Remember,
a slow, sure job is often-time the fastest job overall! Proceed the solder
pin 1 of the CO25953 to pin 1 of U2. Next, solder pin 16 of CO25953 to pin
16 of U2.
13.___Grasp one of those 33 ohm resistors you have previously trimmed and
solder one end to pin 15 of Z3. Z3 you ask? Why that is the chip which has
been piggy-backed on top of U12. U12---you know that one! that's the chip
we so wisely marked before we started!
14.___Cut a short piece of wire and attach it to the free end of the resistor
you just connected to Z3 pin 15. Run the other end of this wire to the
CO25953 pin 10.
15.___Grasp the other 33 ohm resistor and solder it to the 74LS158 pin 4
(this is one of the ones you have previously piggy-backed.) Now take the long
piece of wire you had previously connected to all of the pin 1s of the rams
and solder this to the free of your resistor.
16.___Now take the metal bottom and place the motherboard back into this
17.___At the front of your computer on the lefthand side you will find R108.
Desolder the end of this resistor closest to the front end of the computer.
Solder a short wire to the new free end of this resistor, put heat shrink on
the connection, and connect the wire to pin 11 of the CO25953.
18.___Our next chore is to locate U6 which can be found near the center of
the front end of the motherboard. Please be careful as the traces on this pc
board are very delicate and will not be able to tolerate much abuse. Gently
desolder pins 23 and 24 of U6. The best way to do this is take your solder
wick, place it against the leg to be desoldered,and heat it until you see the
solder beginning to flow into the wick. Turn the motherboard over and make
sure all the solder is off of the pin on this side also. Repeat this step
with pin 24 also. Then take a small, flat-bladed jeweler's screwdriver and
use it to push the pins back and forth a bit. This will free up the pins and
allow you to remove them easily and not tear the living daylights out of the
board! Turn the motherboard back with the parts side up, and use that same
jeweler's screwdriver to pry pins 23 and 24 of U6 out of the board. Leave
them extended in a horizontal direction, snip the thin part of the leg off,
thus leaving the fat parts of these 2 legs for you to connect to later.
19.___Cut a small piece of wire, and strip either end. Connect one side of
this wire to the land where pin 23 of U6 used to be. Fasten the other end of
this wire to CO25953 pin 1.
20.___Cut a small piece of wire, and strip either end. Connect one side of
this wire to the land where pin 24 of U6 used to be. Fasten the other end of
this wire to CO25953 pin 2.
21.___OPTIONAL!:Get your second cup of coffee.
22.___Cut a short piece of wire, strip both ends, and connect one side to the
74LS158 pin 1, and the other side to U17 pin 30.
23.___Cut a short piece of wire, strip both ends, and connect one side to the
74LS158 pin 2, and the other side to U23 pin 15.
24.___Cut another short piece of wire, strip both ends, and connect one side
of this wire to the 74LS158 pin 3, and the other end goes to U23 pin 16.
25.___Cut another short piece of wire, strip both ends, and connect one side
to the 74LS158 pin 15, and the other end to pin 8 of the same chip.(74LS158)
26.___Cut yet another short piece of wire, strip both ends, and connect end
of the wire to CO25953 pin 6, and the other end to U6 pin 35.
27.___Cut another short piece of wire, strip both ends once again, and
connect one side to CO25953 pin 7, and the other end to pin 8 of the same
28.___Cut another short piece of wire, strip both ends once again, and
connect one side to CO25953 pin 9, and the other to U17 pin 26.
29.___Connect one end of this wire to CO25953 pin 12, and the other side to
U6 pin 23.
30.___Cut a short piece of wire, strip both ends, and connect one side to
CO25953 pin 13, and the other end goes to U6 pin 24.
31.___Cut a short piece of wire, strip both ends, and connect one end to
CO25953 pin 14, and the other end goes to the same chip pin 16.(CO25953)
32.___Cut yet another short piece of wire, strip both ends, and connect one
end to CO25953 pin 15, and the other end goes to U6 pin 5.
33.___Cut another short piece of wire, connect one end to CO25953 pin 3, and
the other end goes to U23 pin 12.
34.___Cut another short piece of wire, strip both ends, connect one end to
CO25953 pin 4, and the other end goes to U23 pin 13.
35.___Cut one final piece of wire strip both ends, connect one side to
CO25953 pin 5, and the other end goes to U23 pin 14.
36.___Check all your wiring, and rearrange it to be pleasing to the eye as
well as functional.
37.___Get your SpartaDos 3.2 that has the RD.COM file on it, say a prayer and
load 'er up! If it boots you probably are ok! If not, don't panic, simply go
back through section step by step, you will find it is probably some little
error or oversight.
38.___While you have your computer open it would be a good idea to solder the
joystick jacks, the monitor, I/O and power supply ports also. It may save
you a bit of aggravation later on!
39.___Reassemble your upgraded computer by placing the top metal cover back
over the motherboard. Turn all twist tabs and then insert the appropriate
screws. Gently plug the keyboard back in, position it in its slots in the
cabinets, and then place the cabinet top on. Turn over and insert all screws.
While you have it out, why not use a bit of cleaner on it to make it sharp!
If you don't have SpartaDos, then Run, don't walk to your favorite computer
store and get it!
For you programming types, here are the control numbers for location 54017
Bank # Control # Hex #
Bank 1 ------->131----->83
Bank 2 ------->135----->87
Bank 3 ------->139----->8B
Bank 4 ------->143----->8F
Bank 5 ------->163----->A3
Bank 6 ------->167----->A7
Bank 7 ------->171----->AB
Bank 8 ------->175----->AF
Bank 9 ------->195----->C3
Bank 10 ------->199----->C7
Bank 11 ------->203----->CB
Bank 12 ------->207----->CF
Bank 13 ------->227----->E3<--|
Bank 14 ------->231----->E7<--|130XE
Bank 15 ------->235----->EB<--|Banks
Bank 16 ------->239----->EF<--|
It is recommended to use SpartaDos 3.2, but you can also use MYDOS 4.1
or higher, and also Topdos 1.5 and higher with the 320k series of upgrades.
Enjoy your 130K 65XE!