Regular Posting: FAQ

From: Bill Whitson <>
Date: Tue May 20 22:50:37 1997

ClassicCmp - The Classic Computers Discussion List
FAQ (Frequently Asked Questions) v1.3
Last Update: 5/2/97
This FAQ is written with the primary purpose of making readily available
answers to the more common questions appearing on ClassicCmp. It is
Maintained by Bill Whitson <>. The infor-
mation in this document has been gathered from a variety of sources but,
in general, the members of ClassicCmp should be credited for all contain-
ed herein. I have, of course, endeavored to be as accurate as is possible
and often failed ;).

If you have questions, comments, or corrections (always welcome) please
contact me at the address above.
Updates: New section 2.8
          New section 3.3
          New section 4.3
About ClassicCmp
1. About the List
1.1 What is ClassicCmp?
1.2 Why is ClassicCmp?
1.3 What's a Classic Computer?
1.4 Who runs this thing?
1.5 Don't you know you're duplicating what others have done?

2. Protocol and Etiquette
2.1 What can I talk about?
2.2 Can I talk about PCs?
2.3 Can I talk about Mini/MainFrames?
2.4 Can I post advertisements?
2.5 Can I ask people to give me their computers?
2.6 Can I ask for help fixing item x?
2.7 Where should I look before posting a dumb question?
2.8 Can I type obscenities about Microsoft in ALL CAPS?!?

3. Misc List Information
3.1 How many subscribers are there?
3.2 How many subscribers use machine x?
3.3 Is this list archived?

4. ClassicCmp Resources on the Net
4.1 Does ClassicCmp have a Web Site?
4.2 How come the Web Site is so ugly?
4.3 Does ClassicCmp have an FTP Site?

5.1 Where can I find Classic Computers?
5.2 How much is machine x worth?
5.3 Will thousands of innocent machines be scrapped if I don't save them?
5.4 I just picked up a new machine. What should I do?

Hardware and Media
6.1 What's the best way to clean these dingy tan boxes?

7. Media
7.1 What's a hard sector disk? What's a soft sector disk?
7.2 What's SS/SD, DS/DD, DS/QD, DS/HD, etc.
7.3 Can these formats be interchanged?
7.4 What disk sizes are there?
7.5 How do I take care of old media?

8. Component Failure Issues
8.1 Do EPROM's go bad?
8.2 How about ROM's, other chips?
8.3 How about capacitors?
8.4 Anything else?
8.5 So how do I backup all this stuff like you suggest?

9.1 Where can I get a system disk for platform X?
9.2 What's the best way to back up my software?

1.1 What is ClassicCmp?

It's a mailing list for the discussion of classic computers. Topics center
on collection, restoration, and operation. It is also an appropriate place
for stories and reminiscences of classic computers.

1.2 Why is ClassicCmp?

Uh, why not? There are lots of people who love these old machines and it
seems like a fun idea to get together and talk about them.

1.3 What is a Classic Computer?

Any computer that has not been manufactured for 10 years is a classic.
This definition is one I made up and it's entirely arbitrary. It seems to
work OK, so I've kept it.

1.4 Who runs this thing?

That would be me, Bill Whitson - email

1.5 Do you know you're just duplicating work other people have done.

I get a "reinventing the wheel" e-mail at least once a week. If you show
me another group of computer collectors that claims a membership as large
as this one I'll show you a group that must be very hard to find. Obviously
there are other groups of collectors and I'm cheering them on - I don't see
a problem with duplicating and reduplicating lore that's quickly disappearing


2.1 What can I talk about?

Anything related to classic computers as defined above. There are many
people on this list that really know what they're talking about, so you might
want to check facts before you start shooting off messages.

2.2 Can I talk about PCs?

Yes. PCs which haven't been manufactured for 10 years. Even then, be
aware that in many cases you would get a better response posting to PC

2.3 Can I talk about Minis/MainFrames?

There has apparently been some misconception that this is a list for
micros only. You'll note I said "misconception".

2.4 Can I post advertisements?

Sure. As long as they're related to _classic_ computers. And, of course,
use your brain - don't spam.

2.5 Can I ask people to sell/give me their computers?

Sure. But you're not likely to get a very nice response. Mine, for example,
would be: Get your own f***ing computer! There are several people on
usenet who will vouch for this. When someone posts about one of their
machines without offering to sell it - it's really a pretty good bet that
they're not secretly trolling for offers. See section 5 for info on how to
find yourself a computer.

2.6 Can I ask for help fixing item x.

Yes. Be aware that it may be difficult to help you fix things if you don't
have much knowledge of how computers work or of how to use basic
electronics tools (DMM, soldering iron, EPROM burner, etc). I'm no whiz
with this stuff and the little knowledge I have has come from asking
questions and then buying books to find out what "Simple... Just check
the voltage on the caps in the PS to make sure one of them isn't flaking
out!" exactly means.

2.7 Where can I look before posting a dumb question?

It might be a good idea to take a look at what's available in the Archive
section of the ClassicCmp web site (see below).

2.8 Can I type obscenities about Microsoft in ALL CAPS!?!
Check your anti-MS baggage at the door, please. We all have our opinions
about MS and their products but it's best to stick to discussing them in
reference to _Classic_ computers. MS bashing is not only off-topic but
potentially insulting to those members of the list who work for them.


3.1 How many subscribers are there?

Around 230, fluxing daily.

3.2 How many subscribers use machine x?

Check the web site (see below). The Classic Computer Encyclopedia shows
the number of machines registered by subscribers.

3.3 Is this list archived?

Yes. The archives are available on the FTP site (see below) in the
directory /pub/classiccmp/archive. The file name format indicates
the month/year of the archive. Keep in mind that they are quite large.


4.1 Does ClassicCmp have a web site?


4.2 How come the web site is so ugly?

How come a PET is so ugly? Who cares as long as it works?

4.3 Does ClassicCmp have an FTP site?

Yes. Anonymous FTP at Look in /pub/classiccmp. There's
not much there that's not available on the web site. I'm starting to
load old drivers and system disks on occasion. There is an incoming
directory which subscribers may use for ClassicCmp-related file transfers
if needed.


5.1 Where can I find classic computers?

The best places seem to be thrift stores and swap meets. These are
closely followed by pawn shops and mom and pop computer stores.
The holy grails are electronics scrap yards - but they tend to be wary
of individual pick-and-choosers. Oh yeah - garage sales!

5.2 How much is machine x worth?

Precisely as much as you'll pay for it. Oh, you're selling it? Then,
precisely as much as I'll pay for it. Seriously, no one prices these any
more. I have an old Computer Blue Book that lists many classic
computers but the prices are just ridiculous. Some machines (Apple
Lisa's, old old Mini's, and unreleased prototypes) are starting down
the road toward their original selling prices but it's unlikely that
most will ever be worth more than the cost of their components.

5.3 Will 1000's of innocent machines be scrapped if I don't save them?

Yes. This is the impetus behind every collector's tireless and selfless
effort. Each machine we fail to save has it's gold parts mercilessly
hacked off and sold (just like rhino horns - and look at the rhinos).
The remainder is then sent to China to be made into bicycle spokes (you
probably think I'm joking). Save a computer! Act now! Remind your
wife of the rhino and cuter, fuzzier animals. It might work.

In all seriousness - there are a large (and growing) number of so called
"computer and electronics 'recyclers'" who take usable computers and
recycle them into "reusable scrap". Small amounts of gold, silver, and
platinum are extracted and the remainder of the material is generally
just marketed to less wasteful countries.

5.4 I just picked up a new machine. What should I do?

Don't power it up yet! All of the following should probably be done
before that power switch gets flipped.

Open the case - clean and visually inspect components. You're
looking for traces of smoke, water, corrosion, loose screws, blown
caps and resistors, etc. You can avoid a number of problems just
by taking a peek inside.

If you have the tools (and the machine is sufficiently rare) pull and
dump backups of all EPROMs, ROMs, and PALs.

Disconnect the power supply from the rest of the computer and
start it up on a "dummy load". A six volt headlight bulb has been
recommended as a convenient load. These should be available
from any decent Volkswagen shop. Hopefully this will prevent frying
the rest of the machine with a flaky power supply. You may want to
check the voltage output before you do this as it could be no where
near the 5V average in micros. Even if you don't want to connect
a load it's still probably a good idea to power it up separately from
the computer for the first time. If you have a really rare beast it
may be worth powering up some of the key capacitors out of circuit
just to get them warmed up.

Now you can power it up. Assuming it works, take a blank disk,
format it, write some data to it, and read it back before using your
precious software with it, as a bad disk drive could really ruin your


6.1 What's the best way to clean these dingy tan boxes?

Cases: It seems best to start gently with such old equipment. Try
soaking in a little water and dish soap and then scrubbing. This takes
care of most jobs. For removing stickers try mineral oil or Goo-Gone
(available at most hardware stores - in the US at least). If those
don't work, acetone can be good but, if overused, can do more harm.
For removing marker, almost any solvent is good (alcohol, naptha, etc)
but will definitely discolor or dissolve plastic if not carefully
applied. Lava soap is also good for removing marker but can smooth off
textured plastic. For removing sun or tobacco discoloring a product
called Purple Stuff available from auto parts stores (again, in the US
at least) seems to do the job almost effortlessly.

Connectors: For edge connectors a plain pink eraser seems good
for removing corrosion. Apparently other colors of eraser indicate a
different texture - which may be damaging. Make sure to wipe the
connectors with a clean cloth after erasing on them. There are a large
number chemicals on the market that "magically" remove corrosion from
components but as I don't know how safe they are, I'm not anxious to
promote any of them. For pin style connectors a toothbrush and some
softscrub or other mildly abrasive cleaner do wonders.

Keyboards: I find a cycle through the dishwasher does a really nice
job on keyboards. Just be sure they're completely dry before you
put any power to them.


7.1 What's a hard sectored disk? What's a soft sectored disk?

We'll start with soft-sector since they're simpler to explain. On a
soft-sector floppy disk the information that marks where a sector
begins and ends is written to the disk by the computer (part of the
formatting process). This means that various computers can use
the same floppy disk types because the format of the disk is control-
led by the operating system.

Hard sector disks use a system of perforations in the media to mark
the beginnings and ends of sectors. This means that computers
which used hard sectored disks required the exact disk type they
specified rather than a generic soft-sector floppy. A number of
differently sectored disks were available - at least 10, 13, and 16
sector formats. 8 inch and 5.25 inch disks commonly used hard
sectoring. To my knowledge it was never used with 3.5 inch disks.

7.2 What's SS/SD, DS/DD, DS/QD, DS/HD, etc.

These all refer to the number of useable sides on a disk and it's
density (how "efficiently" the magnetic bits are pushed together).
SS/SD is a Single Sided - Single Density disk, the earliest available
type I believe. The storage afforded by a single density disk was
very small compared to today's standards. Single Sided disks were
popular because they were cheaper than DS and could be easily
modified with a hole punch into double sided disks. SD was followed
by Double Density which, amazingly, doubled the amount of storage
space. Double Density was followed by the extremely short-lived
Quad Density which doubled a DD disk. QD was short lived because
High Density was right on it's heels and nearly doubled disk capacity
again. DS/HD was as sophisticated as 5.25" disks became. 3.5"
disks have progressed as far as DS/EHD double-sided / extra-high

7.3 Can these formats be interchanged?

Well, that may depend on what computer you are using, but in general
the following substitutions may be made:

Desired Format Substitute
Single Density Double Density
Double Density none reliably
Quad Density High Density
High Density none

Other substitutions may be made, but due to physical differences in
how the disks are made they are generally unreliable. It can almost
be guaranteed that data written to a proper density disk of poor quality
will last longer than data written to a good quality disk of the wrong

7.4 What disk sizes are there?

Physically? There are 8 inch, 5.25 inch, and 3.5 inch as "standard"
disks. There are also some unique and/or short-lived sizes such as
3 inch disks used by Amstrad and 2 inch disks which were pioneered
for use in laptops and then quickly forgotten.

7.5 How do I take care of old media?

Step one is Back It Up! After that, make sure it's kept in a clean, dry,
temperature-controlled environment (I keep mine in a broken freezer).
With disks it seems important to keep them standing on end rather than
lying flat - the same goes for cassette tapes. I like to exercise disks
and tapes at least once every six months although I have no real
evidence that this has any positive effect. I have modified an old C64
floppy drive to simply spin when a disk is inserted and send large
stacks of disks through it on a regular basis just to make sure they're
not starting to stick up internally.

An exciting and somewhat recent development is that availability of
classic computer emulators that can make disk images of old media
on PC's and Macs. This seems to be a very good way to backup
disks since they will eventually go bad no matter how well we take
care of them.

The official line seems to be that floppy disks have a shelf-life of
approximately 10 years. With proper care many are lasting a lot longer.


8.1 Do EPROM's go bad?

Definitely. They apparently are considered to reliably contain data for
(on the outside edge) 15 years. This amount can be considerably
reduced if, for example, the sticker over the window has dried out and
fallen off. Luckily EPROMs were not used too extensively but they're
out there. An EPROM writer/reader is a relatively cheap investment
and an easy fix. Even if an EPROM has "forgotten" it's data it is still
fine for being "re-educated".

8.2 How about ROMs and other chips?

Things wear out. It's likely that even components which have not been
fried by catastrophic failure will simply start to die someday. ROMs can
be dumped to a file and re-written if they die. Other custom chips which
are all too common in micros will be far more difficult to replace. The
best advice is to stockpile these chips when you can - but someday even
unused chips will probably start to turn up bad. In this case the best
defense is to stockpile information in the hope of being able to modify
an existing component to meet your needs.

8.3 How about capacitors?

This seems to be another large concern, but rather than being an
unreplaceable component a capacitor will take your unreplaceable
components with it when it goes. It's a good idea to check out all the
caps in a system if you haven't fired it up in a while. Caps go bad
with time (even tantalum caps, apparently - although they are more
reliable) and should be replaced if they are suspect. It's unlikely that
it will be impossible to find a replacement capacitor as they are much
more standard electronic components.

8.4 Anything else?

Documentation: If there's anything which is entirely unreplaceable its
the docs for uncommon equipment. Once they're gone, they're gone.
I regularly pick up docs I find for equipment I don't have just because
I may someday. Paper will, of course. go bad over time but it will be
obvious and they will be easily duplicated.

Hard Disks: ST-251s, ST-502s, MFM, RLL... old hard disks are going
to go bad. Then they'll be gone. Theoretically, I suppose it's possible
to crack a hard drive and replace a dead bearing, realign, relaminate,
etc... but I've never heard of anyone doing these things in their base-
ment. Perhaps in another 5 or 10 years many of us will be experts at this.

8.5 So, how do I back up all this stuff like you suggest?

This answer will undoubtedly get longer as I learn more. The best ways
seem to be to dump the particular ROM (or whatever) using the approp-
riate equipment to a floppy disk (which most of this equipment allows).
Received on Tue May 20 1997 - 22:50:37 BST

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