Building an IBM Compatible
or How to be a real Clone
Baltimore, Md 21206
Although I believe this to be a project that any reasonably intelligent
person can accomplish, the Author assumes no responsibility for failed
attempts, errors, omissions or injuries or losses connected to the use
of the information contained herein. If you need help, get it. If you
are not sure, ask. So there.
Copyright 1990 DJ Elliott. All Rights Reserved.
If received via BBS
I INVITE YOUR COMMENTS AND YOUR CRITICISM. PLEASE SEND ME E-MAIL
WITH YOUR RESPONSE. YOU ARE FREE TO UPLOAD IT TO OTHER BBS'S IN
IT'S ENTIRETY WITH NO CHANGES TO THE TEXT. COMMENTS SHOULD BE
OUTSIDE OF THE ARTICLE.
DJE January,1991 Version 1.3
Revision History- Original November, 1989.
This is a living document. It is being corrected and expanded
constantly. Below is the date of the latest modification.
January 7, 1991
Yes, You Can!
Build your own IBM Compatible Computer
by DJ Elliott
With very little know how and using only what you already know about IBM
Compatible Computers, it is an easy and enjoyable task to assemble an
80286 Machine for a total of about $800. This machine will look like a
store model and do everything a store bought system will do, and leave
you $1000 or more for other pursuits.
The Machine can be built in your spare time in a few days, or over a
number of weeks or months, adding the parts as you can afford them and
find them at the right price.
This author, over three months of occasional work and with no formal
training, built a 12 Mhz 80286 Compatible Machine with 2048K Memory, a
5 1/4 and 3 1/2 Inch drive, a 10 meg hard disk, Parallel and Serial
Ports, and a 1200 bps Modem. Actual work time was in the neighborhood of
10 hours. This unit is a virtual Rocket, running 700% faster than an IBM
XT (source: PC Tools Diagnostics). A soldering gun was used ONCE, to
add a switch (optional for my uses). The gun was the most technical
piece of equipment used. There was no test equipment, special tools or
mathematics involved. This article is written on the described Machine.
Since that time, I have assisted in the building of several other
machines, and advised on many others. Over 300 people have downloaded
the original article. Once you start, you are hooked. I have since
increased memory to 4 megs and bought a used 40 Meg hard drive at a show
for $40 and I constantly improve and upgrade the machine as I learn
more, which is the real lasting fun of the project.
Why build a computer instead of buying it? MONEY and fun. This machine
would easily go for between $1200 and $3000. Most parts are under
warranty, and you are not "stuck" with a computer that does not work.
Just have the offending part replaced or serviced.
Compatibility- What makes this process nearly idiot proof is the
architecture- everything plugs in or screws together. If you can build
a model car with Legos or hook up a stereo, you can accomplish this.
IBM made the decision years ago that the MS-DOS PC would be an Open
Architecture System- a flash of brilliance that led to their domination
of the Market- and made Apple an also ran.
Whatever part it is that you are looking for, it is made by a number of
different manufacturers at a number of different price points, and,
wonder of wonders- they fit into the same slot the same way. An ABC
Motherboard accepts a DEF Controller, which runs a GHI Hard Drive, which
fits into a JKL kit, and takes MNO disks.
Make your decision to build this project, don't look back, and plan on
your Check Writing, Tax Work, Recipes, Letter Writing, and work from the
office to be as close as your living room and as fast as your machine at
This article has evolved from a six page general outline to almost book
length. As of this revision, the article has been split into two
distinct sections: a concise how-to of the basics, followed by lengthier
information that you will most definitely need wither to narrow down
your final buying decision or to support you as you debug your hardware.
The Basic Parts
There are a number of items you will need to get started and they are
easily obtained. All compatibles have the following components:
*A Motherboard (w/CPU and BIOS)
*A Power Supply
*A Keyboard (or other input device)
*A Disk or Hard Drive (I/O device)
*ROM [Read Only Memory] -the basic instructions
*RAM [Random Access Memory]- your work space
The more useful options are:
A second Disk Drive or a Hard Drive;
This article started at 5 pages. It is turning into a book. That's good
in that I'm passing along lots and lots of information that will save
you days or weeks of trouble and lots of dollars. It's bad in that the
technical jargon may turn you off. It shouldn't. The actual building
process is something you absolutely should be capable of doing. Here is
a one paragraph summary of what you will be doing:
You will buy a case, install the motherboard and set a few jumpers per
the documentation. You will fill some empty sockets with memory chips.
You will put in a little silver box that is your power supply. You now
have a computer. You will next insert a card into a slot and hook a
monitor to it. You will plug the keyboard into the back. You will plug
in a card which controls the disk drives, and hook the drives up. You
will turn on the machine and tell the computer about the stuff you have
added. That's it. Really. The balance of this article is to help you
decide which monitor, drives, etc. to buy, and then gives lots and lots
of advice for avoiding pitfalls along the way. Each of these pitfalls
caused me heartaches and headaches. I pass the solutions on to you so
that you may avoid the problems.
If you want to cut to the skinny, here is a short list of the parts for
a recommended system:
You may, for $500-700, buy the following in one morning at a computer
A baby tower case with power supply, an 80286 motherboard, 2 meg of 1
Meg chips (18 chips), a 256K VGA Card, a Mono VGA monitor, a hard floppy
controller, a 5 1/4 and 3 1/2 disk drive, a used 10 meg hard drive and
an AT compatible keyboard.
To do it your way, and to solve problems as you go, read on... Put on
your 70 Nanosecond secret decoder ring, and let's blast off!
Buy a Magazine! (!?!) An indispensable tool is Computer Shopper
Magazine, published Monthly and available everywhere. It lists the
CATALOG prices for everything you need, in all the various options. If
you have three weeks to wait, you will get the absolute best prices on
whatever new and current you want (see Computer Shows for the
exception). Otherwise, you will have the basis for comparison for
shopping elsewhere. A general rule of thumb:
Catalog prices are
- 40% Lower than Discount Store Price
- 60-80% Lower than Computer Store Price
- 20% Higher than Computer Show Price
there will be exceptions, of course.
Example: 1 Meg 80 Nanosecond RAM Chips
Computer Store- $30 each
Warehouse Store- $18 each
Catalog- $9 each
Computer Show- $6 each
The above are actual prices updated regularly with this article.
Spend an entire evening reading this magazine cover to cover- it is
equivalent to an entire College Course in 6 hours. Your head will be
stuffed with new information and insights.
A Brief Description of Your Buying Options; advantages and
Held around the area by different Companies- watch the local paper
Business Section and the back of Computer Shopper Magazine. Careful
buying is the watchword. Buy all your Cables and miscellaneous parts
Ask lots of questions about other pieces from information you gleam
here, from Magazines, and from Books you run across. Knowledge is
Power. They will mislead you to make a sale- but won't make any
patently false statements. My purchase of a 3 1/2 Disk Drive was a
great buy until discovering from the Panasonic Technical Department that
it won't run in Motherboards made after 1985! But the Dealer mailed me
As stated before, the main drawback is the wait; and don't forget that
you have to add shipping and handling costs to the price. Invest the
dollar to call the Advertiser's Technical Line and ask questions: is
this Hard Disk Controller MFM or RLL? Is it 8,16 or 32 bit? (don't get
thrown by this jargon- you will learn it quickly. It's analogous to
asking Is it Front or Rear Wheel Drive? 4 or 8 Cylinders? Someone who
never drove a car would be just as thrown by those questions.)
I have recently had a real nightmare dealing with a Mail Order house in
Texas. We were up to 4 bad shipments before we called Computer Shopper,
who laid down the law to the turkeys. An exasperated president called
the day after we called Computer Shopper and said "What do you want?" We
told him, and we got it. Air Freight. Free. Most houses in Computer
Shopper are very reputable. Just be careful, and call the tech line and
ask lots of questions. If they have no time for you, you have no money
When buying a piece that may take two or three times to install right-
such as a Disk Drive- the extra money may be worth it. Questions like
Which pin is this jumper set on to make this Drive B and High Density?
is tough to answer if you are a Catalog Dealer. Make your decision
based on how comfortable you are installing the part. The best source
of all is the sales and repair place you now use for work. Making
friends with your Service Rep gets you into the back room- where all the
Used but working Parts are kept (and can be bought!!) Where do you think
all the parts went when you upgraded your XT to a 286 at work?
BIG Companies get BIG prices having slick salesmen who frown knowingly
at your questions. They don't want you to buy a part-they want you to
buy a System.
Your first buy:
An XT style Case Allows for an 8088 based Motherboard or a Baby AT-
most motherboards will fit in here.
The AT Case
The "true" AT Case has become a dinosaur. It's a BIG case designed for
an AT size Motherboard. Almost every motherboard I have seen in the last
year fits into a Baby AT configuration, and the new AT size cases have
provisions for fitting a Baby AT board. You would want to pick this case
if you have saved money by purchasing a full size hard drive that will
not fit with two drives in a smaller case.
The Baby AT
(Aw...isn't it cute??) Uses a Motherboard sized to fit in an XT size
case. My original choice. Most AT parts (except a full size
Motherboard, full size Power Supply (XT size) and some 16 bit cards fit
in here. Takes less room, just as fast.
Avoid "ultra slim line" and such cases. If a standard peripheral won't
fit, you are headed in a woefully wrong direction. I have recently seen
some jet black systems. They look really neat, but I haven't seen just
the case in black yet. Maybe I'll paint mine. Maybe not. What do you
A case for those of us who spend extra for a Turbo engine in our car.
Sleek, elegant, and powerful looking. It stands vertical instead of
horizontal. The Power Supply is usually bundled with the case. You can
achieve the same effect (mostly) by buying a $6 stand at a show. There
are two types of Tower cases; those that have to be taken apart like a
standard case (i.e. 6 screws in the back) and those with a removable
side panel that allows access to all peripherals with the turning of two
large screws. This panel makes the IBM PS2 80 a dream to work on.
The Baby Tower
This article just keeps getting longer. The new entry in the field is
pretty reasonable priced. I picked mine up with power supply at the last
show for $129.
Expect to pay $25-80 for the case, over $150 for a tower case with Power
Supply. Buy with confidence from a computer show or catalog. Hard to
mess this one up. Look for panel lights, a keylock, and a flip top
(wish I had one!). You are inside this babe 30-40 times while building,
tweaking and adjusting, and a flip top will make your life easy.
The PC HELP pick: The Baby AT Tower with removable side.
Install the small speaker and LED's (light emitting diodes) and lock, if
any, on the case. The speaker may get annoying. It is loud. Radio
Shack can help you install a little switch to turn it off and a
headphone jack for private listening of the annoying beeps. (This is
where I used the soldering gun). You need to mount these so that the
wires don't pull out when you remove the case!
Now you have a real decision to make- once you make it, you have decided
on the basic Architecture of the Machine and there is no turning back.
You now need to decide whether to buy a 8088, 80286, Baby 80286, 80386,
80386sx or i486 Motherboard. Many Manufacturers. Buy whichever one you
choose with the highest Mhz rating you can afford. Mine is 12 Mhz.
Saving a few dollars by buying an XT board will limit you to a non-
reusable keyboard (unless it is switchable) and hard disk controller, a
hard to replace BIOS, and no Windows 3.0 or other newer software.
INVEST in the Motherboard. Spend the extra $20-50 to get the best you
can afford. Skimp on the replaceable.
The 8088 (XT) Board
Somewhat slow but can be made faster depending on options and speed up
boards. 8 bit technology. For The Person Who Has Lots Of Time To Wait
for Spreadsheets To Recalculate. The technology will soon be as passe
as Leaded Gasoline. Not recommended unless Price is the only
consideration. Analogous to buying an Atari 2600 (lots of cheap
programs around!) rather than a Nintendo or a Turbo-Grafix 16 bit game
system. Why buy something that will be expensive to speed up? Operates
at 4.77 Mhz, with most Motherboards now being "Turbo" (8 Mhz). Most DOS
based resources are downward compatible, though, and you certainly can
build an XT for a truly economy minded system.
Consider this: The 8088 Motherboard can be had for less than $80. IF you
go this route, you need to know if it can support high density floppy
drives. If it doesn't, you will be limited to low density floppies.
Upgrading an older BIOS XT to run these drives and to support VGA
Monitors will cost you $49 from the Catalog. Plus $10 shipping,
handling, postage, etc. $80 + $49 = $129. Cost of a 286 Motherboard:
$95-$119. You may be getting the impression by now that I am trying to
talk you out of an 8088. You got it.
The 80286 Motherboard
The easiest to get cheaper, new technology pieces for. The current
de-facto standard. 16 bit. Fast. Accepts many 8 bit (XT type)
peripherals until you can afford rocket fuel. 8-20 Mhz. Buy as high as
you want to fly. The lowest you should go.
The 386DX and 386SX
For those of us who just have to know the last digit of Pi before
dinner. (Pi should be saved for after dinner. Sorry). Very, very fast.
Will be the standard for the early nineties. A forward thinking choice.
If price is less of an issue, the way to go- the price is coming down
Many people I have spoken to advise against the 386SX as being a step
backward, and that a fast 286 will beat up a stock 386SX. The other side
of the debate is that the SX has the technology on-board to keep it from
becoming passe when developers bypass 286 technology. It gets down to
speed versus being able to use tomorrow's technology. As my mentor Ken
says, "speed ain't everything." You make the call. If this machine is
going to be useful when DOS goes bye-bye, 386SX will keep you in the
race at a price currently quite a bit lower than 386. When I build again
next year, it will be 386. It's getting to the point that its hard to
not recommend building a 386 instead of a 286. Motherboards for the 386
are currently show priced at $399. This may be below $300 in a year.
This is good. The more people make the jump, the lower the price will
be. We're out of order here, but let's finish the discussion on the main
processor. The i486 is just starting to show up as a separate
motherboard. I really don't see any reason to make this plunge if you
are building to save money, unless you need it to run your power plant
or pacemaker or something.
Just coming on the market in large quantities. I don't have enough
experience with them to say whether the speed is noticeable over the
The PC HELP pick: AmpTron 286 with 0/1 wait state, 256/1 Meg sockets, on
board Set up in BIOS. Other Manufacturers with a good reputation
include Morse and Everex. Pay $95-250 based on features. Buy from the
Catalog. The latest system I helped build had made enormous strides over
just six months ago. Expanded Memory (instead of extended) was supported
right from the Motherboard. Another 4 Megabytes of Memory was supported.
Memory caching was built in. All for the same money.
Time out: A word about the BIOS
For whatever board you buy, you must be aware that next to the actual
processor, the most important consideration is the BIOS, so it deserves
it's own blurb.
The BIOS (Basic In-Out system [ooh baby])
Three chips, two for the machine and one for the keyboard. Look for BIOS
built in ($50-100 to add, AND there very well may be compatibility
problems mixing and matching), the word NEW in the Ad (you don't want
something made in 1986; the BIOS needs to be able to work with the new
small Disk Drives). A good question to ask: Does the BIOS read High
Density 3 1/2 inch Disks? If you don't want a high density disk now,
you will soon. Will it take 1 Meg RAM chips? (Cheaper and leaves room
for expansion vs. 256K Ram Chips)? Some take SIMMS or SIPPS modules,
which hook 9 chips together; that's OK. Again, this question will help
you get a board that is fairly new. How many expansion slots? Some
Tandys (Radio Shack) for example only use Tandy Expansion Boards (the EX
and HX). No fun. OK machine, but you are left out of great deals on
boards and peripherals. What is the date of the BIOS? The "main
instructions" to the CPU are handled in these (usually two) chips.
Award, AMI and Phoenix all make BIOS chips, and they upgrade them
constantly. Mr. Mail Order is all too happy to unload a Motherboard with
an old BIOS to Mr./Ms. NewBuilder. I'm not an expert on BIOS chips, but
will pass along that American Megatrends (AMI) is my BIOS of choice, and
produces (or has produced for them? I don't know which) special BIOS
made in cooperation with Chips and Technology (C&T) that come in two
flavors- EC&T which has extended BIOS settings for the true nerd and
DC&T with diagnostics routines built right in. Just don't try to get
tech support from C&T. A VERY good reason for getting new BIOS
(currently April, 1990) is that they (AMI) have a SETTABLE hard drive
table!!! Don't like the choices? Pick your own poison. If you don't know
what I'm talking about, you probably won't lose any sleep over the
Micro Channel Architecture (MCA)
And now a word from Big Blue. IBM wants yer money. They came out with
Micro Channel for two reasons: 10% to improve the computer, and 90% to
destroy YOUR ability to build your computer with inexpensive, readily
available parts. Ignore it, and maybe it will go away. Makes every card
you bought Useless (notice the capital U) by changing the socket that
fits into the motherboard. Boo Big Blue.
Fits into the case with screws and set-offs. Very easy to assemble.
Many Motherboards come with instructions. Mine didn't. If not, take out
of a library or buy a book, such as How to Build an IBM Compatible and
Save a Bundle by Aubrey Pilgrim. Handle this Baby with CARE (the
motherboard, not the book.) LEAVE it in the plastic wrap till you are
ready to install. Put the little white plastic set-offs on the board
first. Touch the Metal Case before touching the Board. Practice
inserting the Motherboard twice before actually putting it in. Visualize
how it is going to slide in. Don't mess it up here!
Plug the Speaker leads and the Power/Turbo LED's on the Motherboard as
indicated. If they don't work when you fire it up, reverse them. Set
the jumpers per the instructions. Pick 0 wait state if your chips are
LESS than 100 Nanoseconds (you'll read about them later). Read slowly
and carefully. It all makes sense. No, you probably don't need a Math
Co-Processor- unless you are related to Albert Einstein.
For an XT, somewhere around 150 watts is sufficient. An AT, you should
spend an extra $20 to go to 200-250 Watts. The higher the wattage, the
more junk you'll be able to stuff inside. For a Baby AT, buy an XT
Power Supply with a high rating (200 Watts). A 386 may need more
My choice: A 200 watt XT Supply (fits a BABY AT). I chewed up two 130
Watt Supplies. Buy from a Catalog or Discount Store. Power Supplies are
the most often repaired item. Don't buy it used. They go up. Pay
Slips into the case via two slots at the front of the supply, then
screws to the Case. Has two plug-ins to the Motherboard. Make sure the
black wires are next to each other when you plug them in. Has 5 or more
plugs to go to Drives and such. The little one goes to the 3 1/2 inch
drive. Except for that one and the ones for the motherboard itself, they
are all the same. Make sure it comes with a Power Cord! If not, it's
a cheap item ($3 at a show).
You will be tempted to check your installation and turn it on for a
second. If you do, you will hear a series of annoying beeps as the
Motherboard comes to life, finds no Monitor, Controller, Drive or
Keyboard and promptly bails out. You should hear a gentle whirr from the
Power Supply. If you see sparks or smell ozone, shut it down (quick!)
and start over.
May be bought refurbished from a store. You MUST buy an Enhanced
keyboard for a 286 or higher. Old XT's used a different processor, even
though the connector still fits! The enhanced has some neat extra keys,
extra Ctrl and Alt Keys, and F11 and F12. Some keyboards are switchable
from XT to AT. Pay $20 (used) to $100 (fancy extras). Look for a nice
click when you press the keys, LED's for NumLock, Caps Lock and Scroll
Has a round plug. Plugs into the back of the case. IBM has a little
round plug on their PS2's, so make sure it's AT compatible.
Ok, now we come to some pure decision making. To keep the as built cost
down, consider giving up color. Just for now. Trust me. If you want
to really plan for the future, though, and want to add $300 that will
make you happy in the long run, go for the gold and add a multi-sync or
multiscan Monitor. Top of the Line. Cream of the Crop. Will run
anything from Mono to VGA, and most probably, anything coming down the
pike for 5 years. I advise AGAINST anything in between. If you buy
something between Mono and Multi, you will have to throw away or trade
for next to nothing to upgrade.
The choices are:
Monographics Monitor. Green, white or amber on a black background.
Does graphics, though! It's hard to beat a Leading Edge Amber Monitor
at $69, available at General Computer. Don't try to use a TV, even if
it calls itself a "Monitor". A TV only does 40 columns across
(characters) and you need 80.
Color Graphics. Also called RGB for Red, Green and Blue. Shows 4
colors (figure THAT math out!). Tandy CGA shows 16. Nice, but a
$200-400 investment that is going passe. Many graphics programs demand
Enhanced Graphics. 16 colors at one time. Was the high end standard a
few years ago. Go higher or Mono.
Video Graphics Array. Puts a picture of your Mother on the screen. In
blushing color. This is where you want to be eventually. "Real" VGA is
.31 dot pitch or LESS. VGA comes in two flavors: analog and digital. In
most electronic and audio applications, digital is better than analog.
In VGA, it's the reverse. Analog is better. You need EGA or VGA to
fully run programs like Freelance Plus (Lotus). You are almost there.
Only problem here is, what happens when VGA is supplanted next year?
Super VGA is enhanced VGA. Has to do with the number of lines of
resolution on the screen. A monitor whose resolution is 800x600 is
considered Super VGA.
You have arrived. Will run anything. Works anything. $300 for a
perfectly good AOC or Morse to $700 (discount) for a NEC Multisync 3D
and up. Check the Catalog. You can find familiar names like Sony and
Toshiba here. CGA runs at a certain frequency, as does EGA and VGA.
Hence, multiple synchronization.
So Mono now, Multisync and VGA later. Read on for the exception.
A Word on VGA
VGA cards are crashing in price. Couple that with the fact that you can
get a "paper white" VGA Monitor (black and white) for $89. Hmmmm...check
it out at the Show before you go Mono. May be irresistible.
The PC HELP pick: The Monochrome VGA Monitor for starters.
Installation: Plug the Monitor AC cord into an outlet, or some plug
directly into the Power Supply of the Computer from the back of the
Machine. Plug the Monitor Cable into the Video Board (next).
The Monitor (video) Board
For whatever monitor you buy, you have to plug a board into the computer
to run it. A used Mono board can be had for $20 everywhere. All those
boards that came out of old PC's and XT's and all the Manufacturer
over-runs are sitting around waiting for you. So you can have up and
running video for $89 or so.
Look for: A Hercules compatible card. This board `interprets' graphics.
With a simple program such as SIMCGA available on bulletin boards or
from clubs, will run most CGA Graphics programs. A bit of a pain. Also
look for a parallel or serial port built in. Saves another $10-60.
Hercules is interesting; a program written for hercules has graphics
better than CGA, EGA and many VGA versions. The graphics are tight and
crisp. Centerfold Squares (Artworks, Inc. My favorite sexist software)
looks better in herc than in Super VGA! But finding herc programs is
getting more harder all the time, and you are still talking black and
COLOR (and Mono VGA)
CGA, EGA and VGA cards plug in the same way. May need software
(provided) to run, and EGA and VGA may have memory slots. Some VGA cards
are downward compatible; that is, you can run Mono, CGA, EGA or VGA with
them. These boards fluctuate WILDLY in price. Stores may ask $200 for
a CGA card, $300 for EGA, $400 for VGA- yet at a recent computer show,
a full function VGA card was being sold for $69. That is why VGA is the
way to go. You must not plug a VGA monitor into a CGA board or something
like that. Make sure your card and monitor are compatible.
There is no need to buy an 8 bit VGA card if you are building an XT.
Simply place a piece of electrical tape over the second connector, and
use the 16 bit card as an 8 bit until you get a 286/386 motherboard.
There may be 16 bit VGA cards that don't work this way, but I haven't
VGA cards are rated by memory; a 256K board is less powerful and slower
to refresh the screen than a 512K board. 256K is certainly adequate for
a starter. I have recently upgraded to 512K, and I don't see much
Plug the board into an expansion slot, advisably the farthest left.
Plug the Monitor cable into the small receptacle on the back of the
card. Use care here. Trying to plug in a VGA Analog connector into the
board blind is the leading cause of Monitor trouble: it fits just enough
to push a pin or two back up into the plug. If you are having trouble
with your monitor, inspect the connector VERY carefully. Gently pull any
pushed in pins back out (With the Monitor OFF), taking care not to
deform the pin. Some Monitors get their power from a plug that goes
directly to the Power Supply.
THE place you will have to do some digging. Think of Memory as a
commodity- the price fluctuates day to day, and when you ask for a
price, the dealer will likely pick up the phone and call some Chip
broker for the latest quote. Seriously! This is due to 1988's chip
shortage. Prices have come way down, but, like gold, some dealers kept
the highest price. PLEASE buy from a Catalog or a Show. Compare
prices. Be patient. A national software chain sells 256K chips for
$19.99. Pay $2 at a show.
Chips come in 64K, 256K and 1 Meg sizes, plus new "banks" of chips in
new motherboards called SIPPS and SIMMS. You may be able to use SIMMS,
but the price may be prohibitive for a while yet. Your Motherboard came
populated (with chips) or at 0K (most likely). There will be a bank of
4, 6 or 8 rows of empty chip sockets. A Memory chip looks like a small
after dinner mint with teeth. Your Motherboard documentation (however
little they provide) will tell you that it takes one or more of these
size chips. Use the highest you can. It takes 9 256K chips to make
256k of memory (or 9 1 Meg ships to make 1 Meg). The ninth chip is for
parity checking and other good stuff.
Motherboards require you to fill two banks (rows) of sockets with chips
to work. You will have to use 18 256K chips to make 512K of Memory. If
you can use 1 meg chips, fill the same two banks with 18 chips and you
have 2056K of Memory!...and you still have empty rows you can fill
later. 1 Meg is the way to go. Buy from a Computer Show or a Catalog.
If you call a dealer, he probably bought from a catalog, and will add
lots of dollars to that price. Pay $2-5 each for 256K, pay $5 to $8 for
1 Meg. Some dealers sell "Pulls", i.e. chips they have pulled from other
machines. You make this call: you are taking a chance. Don't pay more
than half of a new chip's cost.
Chips vary in speed. The LOWER the number, the faster the chip. Usual
values are 70 Nanoseconds, 80 Nanoseconds, 100 Nanoseconds and 120
Nanoseconds. Believe it or not, many vendors charge the same price,
what ever the speed. You can usually have one bank of 80 and one bank
of 100 or 120, but cant mix them in the same row. Lower number chips may
be TOO fast for your machine. That is why new boards are 0/1 wait state
switchable. If the chips are running too fast, you switch back to 1, a
longer wait state. Read up on it.
How much Memory? Anything less than 512K (two banks of 256K chips) is
impractical if you are even going to run a good game or a spreadsheet.
640K- 1 Meg is the most "conventional" Memory DOS can address, and
anything above that is used for a RAM Disk (making your computer pretend
it has an extra disk drive), Print Spoolers (sends printing jobs ahead
and reducing your wait), disk caching and new stuff every day. Windows
3.0 uses as much memory as you can throw at it, and uses it well. 1024K
is usually plenty to start, makes 640K Conventional and 384K extended
(not Expanded) Memory available, but with 1 meg chips, you have to fill
2 banks, so you get 640K Conventional Memory and the rest Extended
Memory. As more programs add uses for so called above board Memory,
there will be more uses for it. Expanded Memory (also called LIM for
Lotus, Intel, Microsoft, the consortium that approved it) is somewhat
more useful, "paging" in and out in 64K chunks to imitate regular
Memory, usable in Lotus 123 and Microsoft Windows and more programs
every day. Your Motherboard documentation will tell you whether you have
Extended or Expanded Memory on board. Some motherboards say "expanded"
and it really is extended. If it is expanded, it comes with a driver to
page in and out in 64k chunks. It uses the same chips. A few of the
newer 386's use Static RAM chips. Some static RAM chips cost $40 APIECE,
and you can't get them even if you have the bucks. Read before you buy.
386 Clone Motherboards use Extended memory for the most part, and you
turn it into expanded as needed by using an Expanded Memory Emulator,
such as QEMM.
If you have never installed chips before, take apart something old, like
a radio or answering machine that no longer works (every house in
America has a broken answering machine, I think). Make sure it is
unplugged (of course) and find an IC chip (described above) (one that's
in a socket, not soldered in) and insert a small screwdriver under the
chip as far as it will go without force. Pull up gently. Stop. Slip the
screwdriver a little further in. Pull up gently. Stop. Insert the
screwdriver under the other end. Pull up gently. That should do it. If
you can't pull it out, there are IC extractors available very cheap (and
very expensive. I had to buy a $60 one for special job) at electronics
stores. Repeat until the chip comes out. Removing chips is a developed
art. I still break them, and the genius manufacturers couldn't be
bothered to key the chips to only go in one way. Put it back in. Repeat
this a number of times.
Go ahead and, with help if needed, install the chips and set the
Motherboard. When you go to install the chips, they are usually put in
with the notch facing the power supply. You usually have to bend the
pins on new chips SLIGHTLY inward. Use something with a flat edge like
a plastic ruler and bend them gently, gently all at once. Make sure they
go in straight and all pins go in. The notch on the chip is usually
matched to a notch on the socket. Get help here if unsure!!! Install the
first chip in a socket that is easy to define, and the others will line
up. Inspect each chip with a flashlight when the chip is in but not
pushed down all the way. Make sure that all pins are inside the sockets,
or start over. When you are comfortable, push down firmly, but not hard
enough to bend the motherboard. Touch something Metal before handling
the chips. Static electricity can make them instant idiots, erasing
everything they learned at the factory. The sockets may be designed to
accept both 256K and 1 Meg chips. COUNT THE PINS and match up the number
of pins on the chips and in the socket. It is incredibly easy to put the
chip in the wrong size socket. There will be a dipswitch on the
Motherboard that you will set to tell it how much Memory you are
installing, and what kind of monitor you have. The documentation will
explain the switch.
Remember, 9 chips in a row for every unit value of Memory (and I said no
Math..oh well). 9 256K chips makes 256K of Memory.
Disk and Hard Drives (I/O devices)
Before you can load a program or save a file, you need to put it
someplace semipermanent. This is because when you exit a program or
turn the computer off, everything disappears! Lost forever. Gone. You
need a device or devices to save to a floppy or hard disk. For budget
purposes, buy a new or used standard 5 1/4 inch floppy disk drive. Try
to buy a half height drive, which only takes half the slot in the case,
so that you can add a second 3 1/2 drive later. The disks are cheap and
will store 360K of information (1K is about 1 page of printed text).
2/3rds of programs you buy will be on 5 1/4 disks. Pay $20-40 used,
$30-60 new. 3 1/2 drives make your life easy. If you can afford it, buy
a 3 1/2 at the same time you buy the 5 1/4. The 5 1/4 is recommended
because most programs you buy come with these disks as the default, and
if you have to boot from this disk (in many games), you need this size
drive and you need it to be "A".
NOTE: If you ever have to call the B drive A for a program, go to a DOS
disk or subdirectory and type ASSIGN a=b,b=a. That will temporarily
reverse the drive assignments. To get back, go back to DOS and type
ASSIGN by itself.
Installation. You need a board. Read the rest of this article before
You need a hard/floppy or floppy controller. You need it to be MFM or
RLL if you will soon buy a Hard Drive. There are other exotic hard drive
types explained later, but, dollar for dollar, MFM still seems to be the
best value, and most compatible. If you are building an AT (286), you
will want 16 bit (two card edges on the bottom) if you want a Hard
For floppy disks only: you can get a half-card floppy controller cheap.
Plug it into an 8 bit slot near the power supply. You need a cable to
go from the controller to the back of the drive. The plug will be marked
1 on one end and 36 on the other. 1 usually goes on top. There should
also be a different color wire on one end of the "strap" of wires. This
color designates wire one. If the disk drive lights and doesn't go out
when you fire up, you have it backwards. The other end of the cable
should have two card edge connectors, marked with numbers as described
above. There is also usually a slot in the female portion keeping you
from putting it on backwards. One card edge connector may have a twist
in the cable near the connection. This and the fact that it is the end
of the cable indicates the Drive A connector. Plug it into the back of
the drive, which you have slid into the slot in the case. Plug one plug
from the power supply into the drive. If you have bought a second
drive, the other card edge connector hooks to that drive to make it
drive B. You MUST follow the manual for the drive or call the
Manufacturer to set the little jumpers on the drive near the back to get
the drive configured correctly. To me, this is the most frustrating part
of putting a system together. Most manufacturers use jumpers which are
tiny black sockets that connect two pins together. They are near
impossible to remove with or without tweezers, and sometimes you end up
having to move these jumpers 10 times or more to get the configuration
right. Hey manufacturers, use dipswitches! With a twisted floppy control
cable, set both drives to the second position, which may be DS1 or DS2,
depending on whether the manufacturer starts counting at 0 or 1. In any
event, it's the second drive position.
For hard drives, you need a separate controller, or a Hard/Floppy drive
combination controller. In most cases, you will be using the latter.
Follow the documentation.
Types of Floppy Drives
Besides the old standby 360K 5 1/4, there is a high density 5 1/4 that
stores 1.2M of data. This drive is problematical. You will not be able
to write to a low density diskette and use it on another computer with
a low density drive. There are also 3 1/2 inch drives. The disks it
uses are hard, less likely to go bad, and fit in your shirt pocket
without a sleeve. Wonderful. Buy one as a second drive. Stores 720K.
High density 3 1/2 drives store 1.44M, and aren't as problematical as
high density 5 1/4's and surprisingly, are only about $10 more than low
density! Buy the high Density. Pay $30 (used) to $75. Installation
note: I had my 3 1/2 high density drive set to Read Media, which meant
that the drive decided which type of disk was in the drive. A friend
gave me a program on a high density diskette. The machine wouldn't read
it. To make a long story short, she had formatted the high density
diskette to low density, and the drive to trying to read high. I
changed the jumper to read the disk type from the machine instead of the
Toshiba drive. Problem solved. If your BIOS routine sets disk types in
the Setup program, do it this way.
ANOTHER NOTE: This will pay for reading this article many times over. If
your BIOS is set in the set up routine to read high density diskettes,
and the drive is high density, setting the jumpers right on most models
will let low density diskettes format to high density! There. I've just
saved you $3 a diskette for the rest of your life. Send $10 to
Caution: Some computer manuals claim that you should never do this. They
say that the low density disks are not made to be formatted high, and
you will lose data. I have NEVER had this happen, so you make the call.
If the only copy of your will is on a low density disk formatted to
high, back it up somewhere. Personally, I could write my will on the
label of a 3 1/2.
Ok, ready for some jargon? There are MFM drives (usually old) RLL, SCSI
(pronounced scuzzy for some warped reason), IDE and ESCI drives. Buy
whatever you get the best deal on, and fills your purposes (if you can
afford ESCI, you probably aren't interested in building) but your
controller MUST be compatible with that type. buy a 16 Bit controller
card. You can get 10,20,30,40,80 and up Megabytes of memory. Read up on
it. 30M is about the best compromise for the limited-income builder.
Buy a compatible Hard/Floppy controller (MFM or RLL [higher capacity by
increasing the sectors]) to match the drive and 8 bit for XT or 16 bit
for AT) to control all the drives. Buy a half height if possible to
save room for a second hard drive. I installed a 10 meg full height
(great buy!) and filled it in two days. Word Perfect took 2M. Symphony
took 1.5M. Windows 3.0 needs 3-6 million and is worth every byte. And
on and on. Pay $50 (used) to $600 for a hard drive. Pay about $225 for
a 20 Meg. Get a book on formatting. Get the shareware programs IAU and
HDDIAG from a bulletin board or a Computer Show. Ready for a crap shoot?
Show up at a show AT OPENING TIME. Someone will invariably be there
selling hard drives pulled from old machines for $1 a megabyte. For
thirty dollars you can take home a 30M drive that has a 50-50 chance of
working. Like I say, you make the call. I bought a 42MB voice coil (as
opposed to stepper motor) drive for $40; it only needed re-formatting.
Then again, chances were just as good that this drive was used as an
anchor for a crab pot for six months. Again, it's a crap shoot.
Hard drives come in full size, half size (both 5 1/4) and 3 1/2 size. BE
SURE that the case you buy will take a full size hard drive and two
floppies before you buy a full size drive.
Drives are also split into Stepper Motor and Voice Coil. Be aware the
stepper motor will give you great service, but cannot be moved without
"parking" the drive. A stepper motor hard drive is just like a
turntable; if you shake the drive, the needle will go skittering across
the surface of the drive platter, destroying data as it goes. Most hard
drive repairs are reformatting as a result of the user banging the
machine around, or, (GASP!) turning the machine over and shaking it to
get out a loose screw. Voice Coils can be safely moved, and are more
expensive. Ask the seller which the drive is.
High Tech Hard Drives
SCSI works by putting the controller on the Hard Drive, and the floppies
work off of that controller. IDE is an animal unto itself. IDE also puts
the controller on the drive, and then plugs into a card (not a
controller?) that also has the parallel, serial, game port and floppy
controller on the same card. I just installed one in my system. I can
see NO speed improvement over my Adaptec MFM controller.
There is a big cable that goes from the Hard Drive to the controller and
a small one. Match pin one to pin one all the way around. Slide the
Hard Drive into the case, connect these cables, and plug in the power
supply lead. For two drives, get a book and follow the instructions.
It's not that hard, but you have to deal with twisted cables and
terminating resistors and such. The terminating resistor goes on the
last physical device.
The hard drive must be set up in your BIOS program, then low-level
formatted and high level formatted. Pick up a book at the library,
borrow one or ask a friend. The procedure is not difficult. The two
aforementioned share-ware programs IAU and HDDIAG makes the process easy
and configures the drive to it's optimum performance.
In 286 and 386 machines, you must pick an entry from your Set-up
program, which comes up when you start the computer. It is accessed by
a particular keystroke, referenced on the screen before the machine
actually boots DOS. The message will say something like "Press DELETE to
enter Set-up". Set-up writes your component information into the CMOS.
CMOS stands for something or other which I always forget.
Shareware programs are available to help you pin down which "number" of
a standard set of numbers your hard drive type is. An old IBM 10 meg
drive is #1. An old Seagate 412 is #23. The BIOS will ask you for this
number. If you bought from Crazy Johns Unguaranteed Hard Disk Bargain
Nearly New Shop, you may have to do some digging to find the number.
Disk Manager, which comes with Seagate Hard Drives, will interrogate the
drive for you, but is a real pain in the butt when the drive isn't
Seagate. Here's a real kluge. My hard drive didn't fit my table, so I
hooked the hard drive up to a machine with a settable drive table,
formatted it, then saved the settings to the disk with Disk Manager. If
the drive ever crashes, I'll probably have to repeat this process or
update my BIOS. You need to know the number of cylinders and number of
heads, at a minimum. The number of sectors for MFM is usually 17
sectors, RLL 26 or 27. Call the local computer club to track down a list
of hard drive specs. You match the number of cylinders and number of
heads in the drive table in your set-up program WITHOUT GOING OVER. Just
like the Price is Right (hi Bert!). If your drive has 8 heads, you can
pick 5,6,7 or 8, but not 9.
Skip this paragraph unless you end up with an IDE drive. I just learned,
by force, how to set up one of these bears. The IDE drive table entry is
determined by MULTIPLYING the number of heads x the number of sectors x
the number of cylinders, and matching that to the drive table entry that
most closely equals the number of heads x cylinders x sectors. Sheesh.
The advantage is, you are not limited to the closest without going over
rule. The one thing you MUST NOT DO is low level format an IDE drive!!!
They are low level formatted at the factory. If you do a low level
format, it becomes an MFM drive. This exciting information was passed on
to be by the Seagate technical department AFTER I had low level
formatted three times trying to ge the bear to work. There was NOTHING
in my documentation telling me not to do a low-level. I had to get
another drive and start over to get the full performance from the drive.
Formatting the hard disk is involved but not difficult. HDDIAG and
AMIDIAG (AMI, the BIOS people) are both free or shareware programs
available at Computer Shows and through magazines for a couple of bucks
each (Registration will cost more. These folks deserve their money.)
They will walk you through the low level formatting, which prepares the
disk for your system. Seagate and some other manufacturers come bundled
with Disk Manager, which is a great utility, but only works with that
brand hard drive. Next you run your DOS program FDISK, in which you set
up the DOS partition. If you are running DOS 3.3 or less (hardly anyone
likes DOS 4.01) you are limited to 32 Megabytes per partition. Thus, a
40 Meg harddrive must be split up into more than one partition (C and D
[and maybe E]). A drive runs faster if you minimize the C partition and
maximize the others. The D and above partitions run much faster. No big
deal to run FDISK. Finally, you high level format the disk, i.e. format
C:/s which makes the hard disk ready for use and bootable and format d:
which prepares the D drive. Take this whole process slow and easy. Block
out quiet time to do it.
You may not be ready for this yet, but here goes. There are Ports for
adding peripherals to your machine, just like you add a CD or turntable
to your stereo. A mouse usually needs a serial port or works off of it's
own card, and a printer a Centronics Parallel port. The following will
NOT a full diatribe on ports, but a starting point.
This one is easy. Plug the 25 pin end into an I/O card you have bought
for the computer. Plug the weird looking end into the printer. This port
is usually called LPT1.
Also known as RS-232. Usually a 25 pin connection. A little more
complicated, but faster and more versatile than parallel. Don't get
scared by all the technical jargon that comes with serial port devices.
I've rewired one ONCE for a special application, and I install about 400
of them a MONTH. Serial ports most often are for Mice, scanners,
plotters and external modems and such. The serial port is the place most
computer hacker wanna-bes have trouble. They represent 80% of my trouble
calls. The first and best advice is, KEEP IT SIMPLE. DON'T mess with an
IRQ that works, and NEVER, NEVER change the memory address of a COMM
port. Okay, okay, I'll back up. There are COMM ports for serial devices.
COMM 1,2,3 and 4. You use them in order as you need them. Usually the
Modem (Modular/DEModulator), which allows you to call Compuserve and
give them all your money is COMM 1 and the mouse is COMM 2. COMM 1 is,
by default IRQ4 (Interrupt ReQuest 4) and COMM 2 IRQ3. Each has a memory
address. Here's the dangerous part: you are advised, in the worst pidgin
english in the manual to mess with flipping IRQ and memory addresses and
COMM port assignments around. Please don't!!!!! Leave it alone. Keep it
simple. Messing with them is akin to switching spark plug wires in your
car. All you need to know unless you futz with them is:
COMM3 and COMM4 work off IRQ 4 and 3 respectively, but at different
Don't call me if you mess with IRQ's. It gives me a headache. If you
futz with the memory address, I won't even talk to you at the Christmas
To summarize, put in the I/O board, hook up your printer (I like the
Panasonic KXP 1124), call it LPT1, hook up your preferably internal
modem as COMM1, IRQ4 and your mouse as COMM2, IRQ3 then leave it alone.
You have been warned.
You have installed the Motherboard and Power Supply, hooked up the
speaker and LED's, inserted the Memory chips, set the Motherboard
dipswtich(es), put in the Monitor Card and plugged in the Monitor,
plugged in the keyboard, inserted the Hard/Floppy Controller, slid in
and connected the drive(s), and plugged the whole shebang into the wall.
You have left the I/O card and any optional devices such as mice and
printers out of the picture until the basic machine is working well.
Now turn it on.
If everything is hooked correctly, the Memory will count off as it is
checked, and you will be sent (hopefully) to a set up program in BIOS to
describe and save the configuration of your system. You now need to add
MS-DOS from a disk to "Boot" the computer, and you are up. The moment
you see your first A> prompt you are in business. Open a bottle of
champagne, pour one for me, and accept my hearty congratulations.
Piece New or Used Source Price
Case- Baby AT New Catalog $25.00 $25.00
Motherboard-AT286 Amptron New Friendly Rep $199.00 $109.00
Monitor-Leading Edge New Gen. Comp. $69.00 $69.00
Mono Card w/ parallel port Used Friendly Rep $20.00 $20.00
Power Supply 200 Watt New Disc. Store $69.00 $46.00
Teac 5 1/2 Drive Used Show $40.00 $40.00
Toshiba 3 1/2 HD Drive New Disc. Store $89.00 $79.00
IBM MFM 10 Meg Hard Drive Used Show $20.00 $20.00
Adaptec Hard/Floppy Controller Used Friendly Rep $69.00 $69.00
Memory- 18 1M 80NS Chips New Show $162.00 $108.00
Serial Port Used Show $10.00 $10.00
Modem 1200 bps (optional) Used Show $20.00 $20.00
Switch and headphone jack (opt) New Radio Shack $4.00 $4.00
TOTAL $796.00 $619.00
THE COMPUTER SHOW SHOPPING GUIDE DJ Elliott DID I
I WANNA VENDOR GET A
COMPONENT STYLE PAY ________ ________ ________ RECEIPT?
CASE XT ______ ______ ______ ______ ______
AT ______ ______ ______ ______ ______
BABY AT ______ ______ ______ ______ ______
TOWER ______ ______ ______ ______ ______
MOTHERBOARD 8088 ______ ______ ______ ______ ______
80286 ______ ______ ______ ______ ______
BABY 286 ______ ______ ______ ______ ______
386SX ______ ______ ______ ______ ______
386DX ______ ______ ______ ______ ______
POWER SUP ____WATT ______ ______ ______ ______ ______
FLOPPY DR. 5 1/4 LOW ______ ______ ______ ______ ______
5 1/4 HI ______ ______ ______ ______ ______
3 1/2 LOW ______ ______ ______ ______ ______
3 1/2 HIGH ______ ______ ______ ______ ______
HARD DRIVE ___ MEG ______ ______ ______ ______ ______
___ MEG ______ ______ ______ ______ ______
___ MEG ______ ______ ______ ______ ______
DRIVE HD/FL COMBO ______ ______ ______ ______ ______
CONTROLLER MFM 8/16 BIT ______ ______ ______ ______ ______
RLL 8/16 BIT ______ ______ ______ ______ ______
OTHER 8/16 BIT ______ ______ ______ ______ ______
CABLES ______ ______ ______ ______ ______
FLOPPY 8/16 BIT ______ ______ ______ ______ ______
CABLE ______ ______ ______ ______ ______
MONITOR MONO ______ ______ ______ ______ ______
CGA ______ ______ ______ ______ ______
EGA ______ ______ ______ ______ ______
VGA ______ ______ ______ ______ ______
VGA MONO ______ ______ ______ ______ ______
MULTISCAN, MULTISYNC ______ ______ ______ ______ ______
MONITOR HERC MONO ______ ______ ______ ______ ______
CONTROLLER CGA ______ ______ ______ ______ ______
EGA 8/16 BIT ______ ______ ______ ______ ______
VGA 8/16 BIT ______ ______ ______ ______ ______
CABLE ______ ______ ______ ______ ______
MEMORY 256K CHIP ______ ______ ______ ______ ______
lower 1 MEG CHIP ______ ______ ______ ______ ______
nanoseconds OTHER CONFIG ______ ______ ______ ______ ______
I/O BOARD __PARALLEL ______ ______ ______ ______ ______
__SERIAL ______ ______ ______ ______ ______
__GAME ______ ______ ______ ______ ______
KEYBOARD ______ ______ ______ ______ ______
MODEM _____BPS INTE ______ ______ ______ ______ ______
_____BPS EXTE ______ ______ ______ ______ ______
_____BPS INTE ______ ______ ______ ______ ______
_____BPS EXTE ______ ______ ______ ______ ______
MOUSE BUS ______ ______ ______ ______ ______
SERIAL ______ ______ ______ ______ ______
PRINTER DAISY WHEEL ______ ______ ______ ______ ______
DOT MATRIX 9P ______ ______ ______ ______ ______
DOT MATRIX 24 ______ ______ ______ ______ ______
LASER ______ ______ ______ ______ ______
CABLE ______ ______ ______ ______ ______
FAX BOARD ______ ______ ______ ______ ______
SCANNER ______ ______ ______ ______ ______
BLANK DISKS______________ ______ ______ ______ ______ ______
SOFTWARE ______________ ______ ______ ______ ______ ______
SOFTWARE ______________ ______ ______ ______ ______ ______
SOFTWARE ______________ ______ ______ ______ ______ ______
SOFTWARE ______________ ______ ______ ______ ______ ______
SOFTWARE ______________ ______ ______ ______ ______ ______
OTHER ______________ ______ ______ ______ ______ ______
STUFF ______________ ______ ______ ______ ______ ______
Get a receipt. Get a phone number and address. Get a guarantee.
The unaltered document is 9277 words.
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