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On December 23, 1992, I did a brain transplant on my computer.
By installing an ALL 486SX-25 CPU upgrade, I transformed my 10
MHz, 286 Tandy 3000NL into a machine that in some ways
outperforms a 25 MHz 486SX computer. As a sort of pioneer in
trying this on a Tandy 3000NL, I had some problems. I hope my
experiences will help others get a pain-free upgrade.
WHY UPGRADE:
About a year ago, I was beginning to feel left out of
developments in computing. Programs such as Windows run too
slowly to bother to put on a machine like the Tandy 3000NL. OS/2
2.0 will not run at all on a 286 machine. The multi-media
standard requires at least a 386SX. New memory management
software, such as QEMM or those found in DOS 5.0, cannot be
used on a 286.
I wanted to keep somewhat satisfied with my system for 2 - 3 more
years. I began looking at my options: 1) I could buy a new
system. 2) I could get a new case, power supply, and
motherboard. 3) I could replace the motherboard. Or 4) I could
try a CPU replacement module.
I felt that options 1 and 2 would be more than I wanted to pay.
(Yes, I know that there are some very cheap systems available.
And some of those cheap systems are really inexpensive, high
quality systems. But I want to stick to systems that have some
reliability and corporate track record to them, which is why I
got the Tandy 3000NL in the first place.) I also have trouble
parting with old systems. I did not want to add a 286 box or
system to the Tandy 1000A or the 2 Timex/Sinclair computers
already hanging around my home. I also try to upgrade a piece at
a time, and reuse (for at least a while) the hardware from the
old system. This keeps down my cash outlay at any one time.
I felt that option 3 would be a lot of trouble, although it
probably would have been faster, and possibly a little less
expensive, than replacing the CPU. I know that the power
connectors from the T3000NL power supply need to be rewired.
Also, the parallel and serial ports would have to be replaced.
This would either sacrifice a precious slot on the buss, or
require some more rewiring to use the openings already present.
I have done enough electronics work and soldering that I am
confident that I could have done all that, but did not really
want to do it. The memory I had at the time was a mixture of 80,
100, and 120 ns chips, and would have been too slow for a new
board. The new memory would have added to the cash needed.
Also, I would have had that 286 motherboard to add to my computer
collection.
That left option 4. After checking with the various
manufacturers, including AOX, Evergreen, MicroWay, SOTA, and
Cumulus, I found that some (such as AOX, Intel, and Kingston)
were not compatible with the 3000NL, some (such as Cumulus and
one of the Evergreen adapters) were compatible but would run a
386SX at the 10 MHz clock speed of my computer, and two (SOTA and
MicroWay) claimed to be compatable with a 3000NL. The MicroWay
would take one of my precious 16-but slots. The SOTA was
attractive, and I almost bought it, but decided to wait. Then I
got a postcard pack advertising a 286 to 486 upgrade. I called,
and found that it was the ALL 486SX. It used a hot new chip
(Cyrix 486SLC), included a 25 MHz clock, cost about the same as
the SOTA, and _might_ be compatible with the 3000NL. The Cyrix
486SLC also has a 1 Kb internal cache, executes the entire 486SX
instruction set, looks like a 486SX internally, and executes some
486 instructions (such as Multiply) faster than a real 486SX.
Systems using this chip were getting very good performance
reviews in August and September. I recognized the ALL Computing
name; a few years ago they developed hardware to allow a 286 to
map memory like a 386. Since there was a 30 day money back
guarantee, I took a chance and ordered it.
INSTALLATION:
My installation took almost 3 months to complete. Since ALL
Computers has solved the problems, your installation should take
about 20 minutes.
My first problem was the software. It was on HD 5.25" diskettes.
This was easy to solve. Since I do not have a 5.25" HD diskettes
drive, I had a friend copy the HD disks to 3.5" diskettes. I
installed only the cache software. I did not install the ALL
memory manager because I wanted to use QEMM.
I removed the 3 screws in the back panel that hold the case
together, and removed the cover. The 2nd 3.5" drive bay is
directly over the CPU, and had to be removed. Two screws hold
this on in the front, and the bay is removed by sliding it back.
The lithium battery was near the CPU and needed to be moved
aside.
The Tandy 3000NL has the 286 CPU in a PLCC (Plastic Leaderless
Chip Carrier) socket. The CPU will have a number like 80286 or
286 somewhere on it, and by manufactured by either Intel or AMD.
(AMD made mine.) (There are other PLCC sockets on the board, but
these contain the Chips & Technologies (C&T) chip set. Most of
these are also larger than the CPU.) The jaws of the chip
extractor fit in 2 notches in opposite corners of the socket.
Following the instructions, my chip came out fairly readily, but
the jaws did slip a bit.
I located the blunt corner of the socket, and aligned the
connector of the adapter. Problem: On my computer, there is
almost no space between one edge of the ALL 486SX ChargeCard and
the front panel. I could just barely get it to fit. I later
found out that there is a cable adapter available that allows the
ALL 486 to be installed where there is more clearance. Although
I did not need this adapter, at least one Tandy 3000NL owner
needed this. There are at least 2 versions of the motherboard,
and even a small difference in the location of the CPU would
prevent the ALL 486 from fitting easily.
My real problems began at this point, and required almost 3
months (end of September to December 22) to solve. After
upgrading my BIOS, and after receiving a reprogrammed ALL 486 on
December 22, everything went very smoothly. But before that
. . .
My first attempt resulted in the ATI video BIOS display on the
screen, followed by the Tandy BIOS display (version 01.04.02),
followed by . . . nothing. I got this result even after pulling
all the boards except the video adapter.
I spent a fair amount of time on the phone with ALL Computers'
technical support staff, who were knowledgeable and supportive
through the ordeal. Two probable problems came up: The ALL 486
was not compatible with Phoenix BIOS versions before version
3.07, and could have problems with certain C&T chip sets. It
turned out that I had both.
On CompuServe, I found a utility to identify the C&T chip set.
This included documentation giving the Micro Firmware BBS phone
number. That BBS also had utilities to identify the Phoenix ROM BIOS
versions. (It turned out that Micro Firmware is the only
supplier of Phoenix BIOS upgrades. More on that later.) I found
that my Tandy BIOS (dated 10/13/88) was based on a "problem"
version of the Phoenix BIOS, and that my C&T chip set was the C&T
CS 8221.
BIOS REPLACEMENT:
I came across a magazine article identifying Micro Firmware as
the Phoenix BIOS upgrade supplier, and ordered the upgrade for
$73.37, including shipping. Although I did not attempt to test
my second ALL 486 with my original BIOS, I believe that the
upgrade is still required. The upgrade provides some
enhancements, such as set-up in ROM (invoked by pressing CONTROL-
ALT-S), password security, user defined hard drive types, support
for 2.88 Mb diskette drives, and hooks to DOS and Windows that
supposedly provide a dramatic performance increase in extended
memory access. If you do not want to spend the extra money up
front, you could try your old BIOS with the ALL 486.
I felt that replacing the BIOS was harder than replacing the CPU
-- mainly because the old ROMs do not come out easily. I used a
combination of a Radio Shack chip extractor tool, a small flat
bladed screwdriver, and much gentle prying at each end of the
chips to remove them. The process took about 15 minutes. Micro
Firmware has good instructions on replacing the chips. The BIOS
is on two ROMS. My old BIOS was marked even and odd, so it was
easty to figure out which chip went where. Since the new ROMS
were 32K instead of the 16K originally installed, I had to change
some jumpers to E26-E27 and E28-E29. The jumper settings are
documented on page 44 of the Tandy 3000NL Installation and
Operation Manual. The manual also has pictures on page 7 and 8
that show the location of the jumpers.
After replacing the BIOS, the Setup procedure must be done. You
will find that the new setup allows changing some features on
your system. Micro Firmware supplies a utility to figure out
what features were set BEFORE replacing the BIOS. You should
print these out so you can set up in the same way. THEN if you
play with the other options, you can always get back to a
configuration that works.
C&T CHIP SET COMPATIBILITY:
ALL technical support informed me that it was the intention of
ALL to support all the C&T chip sets. An adapter (or possibly a
reprogrammed PAL) was being prepared to solve my problem. They
gave me an RMA number for the return of my unit, and said that
they thought that a replacement that would work with the Tandy
3000NL would be shipped in about a week. For reasons that I do
not understand, the one week stretched into almost 10 weeks.
However, when I finally did receive the replacement unit, it had
been tested on all kinds of C&T chip sets and mother boards
(except for the Tandy 3000NL!!!) ALL technical support was
fairly confident that it would work, and I am pleased to report
that it works very well.
RESULTS:
Most programs appear to run somewhat faster than before.
Programs such as FRACTINT, which can take advantage of the 1K
cache memory and the enhanced hardware multiply on the Cyrix
chip, run MUCH faster than ever. Fractals done using floating
point math appear to get done as fast as a 3000NL with a 287
coprocessor. One freeware program (look for ASQZIP.ZIP on
CompuServe) reports a CPU speed of 184.5 MHz, which is not right.
I do not have a standard benchmark program, such as SI or
Landmark, so I can't report those results. I expect that due to
the mixture of slow memory and a fast processor, the overall
performance is like a 20 or 25 MHz 386SX.
The biggest improvement is that I am no longer locked out of new
programs which require a 386 or better processor. I can use the
copy of QEMM that I bought in anticipation of upgrading my
processor, and I can get full use of DesqView's multi-tasking. I
could run Windows at some acceptable speed (if I ever decide to
get Windows!) and I should be able to run OS/2.
------------
ADDITIONAL INFORMATION
My hardware:
. Tandy 3000NL, 8 M memory on Tandy 25-4027 memory expansion
adapter, with Phoenix ROM-BIOS upgrade A286 1.01 for C&T
CS8221 (NEAT) chip set. (The memory and BIOS were upgraded
during the time I was waiting for the ALL 486.)
. ATI VGA Wonder video board
. NEC 3D monitor
. Always IN-2000 SCSI hard disk controller, with Seagate ST296N
drive
. 3.5" HD diskette drive
. 5.25" 360K diskette drive, pulled from Tandy 1000A
. BocaRam AT Plus Memory board with 2 M memory
. Creative Labs Soundblaster Pro sound board
. DAK video capture board
. Marstek hand scanner controller.
Product Information:
ALL 486SX Chargecard
. Cyrix 486SLC processor, 25 MHz clock
. ALL Charge 386 memory management software on a 5.25" HD disk
. Chip pulling tool
. Installation instructions
. Software to activate the hardware cache on a 5.25" HD disk
. Manual on the hardware should be included now.
Micro Firmware BIOS upgrade
. Phoenix BIOS, A286 version 1.01 for C&T CS8221 (NEAT) chip
set (Phoenix started a new numbering scheme since version
3.7)
. Diskette of utilities, including one to figure out hard disk
parameters, a low level disk formatting utility, the set up
program, a utility to show the type of chip set used in your
computer, and a utility to assign port addresses for serial
ports.
Sources:
. Tech Direct (Sells All 486SX Chargecard)
Sales: (800) 275-8344
. ALL Computers (Manufacturer)
Information: (216) 564-7875
. Micro Firmware (Sells Phoenix BIOS Upgrades; has software on
BBS to identify BIOS versions and C&T chip sets)
Sales: (800) 767-5465
BBS: (405) 321-2616
If you take this route to upgrading and have any problems, please
drop me a note on the CompuServe Tandy forum.
Don Parth