Herb's S-100 FAQ - Frequently Asked Questions

To go to my S-100 home page click here.
To order S-100 stuff from me click here

The S-100 bus is a bus standard for computers of the 1970's and 80's which had 100 pins on each computer card. This links to a description of that bus. The S-100 bus computers used 8-inch floppy drives and other old technology, and often ran CP/M. So, this site has some information about those things as well. If you have some general questions or are not certain about your needs or interests, please read this editorial first.

Floppy disks: Many questions about S-100 systems are about floppy disk drives or diskettes. Some of those questions are below. I have an extensive set of Web pages about floppy drives. Please check this floppy drive technical page for more information and links to those other pages.

restoring old systems I have a whole Web section about repair, restoration, and display of old computers, at this Web link.

CP/M Some of these questions relate to CP/M. CP/M is now discussed on my how-to CP/M Web pages.

For your particular question check below. Contact me via my ordering Web page if you need more info or have a different question or comment.

S-100 Frequently Asked Questions (FAQ)

Editorial: General requests for computers, help, discussion
0) Where is the CP/M FAQ for comp.os.cpm?
1) What is my S-100 system worth? Is there a market for it?
1.1)Why is the S-100 world of any interest or value today?
2) I gotta get rid of my S-100 system NOW!
3.1) I got this neat S-100 system. How do I make it work(?).
3.2) Where do I get more information on (whatever)?
4) How do you find the time and resources to do this?
5) I'm interested in (your choice) but I don't want to spend much money.
6) I want to buy an (IMSAI, Altair) from you or someone
6.1) I want to build an (IMSAI, Altair) replica, clone, model..
6.2) Do you have any recommendations for someone who would like to purchase a functioning IMSAI 8080 [or MITS 8800]?
6.3) Where did the names "Altair", "S-100" come from?
7) This is not an S-100 item, but I'm looking for (your choice)
8) You have a list? How much for, or do you have, (your choice)?
9) I want to read CP/M disks from my [previous CP/M system] on my PC Windows system.
9.05) I want to run CP/M programs from my [previous CP/M system] on my PC Windows system.
9.1) I want to read hard sectored CP/M disks on my PC Windows system.
9.2) I want to read old MS-DOS [unusual format] disks on my PC Windows system.
9.3) I want to read MS-DOS disks on my CP/M system.
9.4) I want to read (odd format) disks on my Windows system.
9.5) where can I find someone to read my 8-inch or CP/M or ??? diskettes?
10) I want to hook 8-inch floppy drives to my PC / Windows / Linux system...
10.05) I want to read 8-inch floppy disks on my PC / Windows system...
10.1) I want to hook a 3.5 inch drive to my 8-inch floppy drive system; or a 3-1/2 inch drive to my 5-1/4 inch drive system, etc...
10.2) I want to hook floppy drives (run CP/M) on my S-100 system...
10.3) I want to run a hard drive on my S-100 system...
10.4) I want to replace my MFM hard drive with an IDE hard drive...
11) Please describe the details of the S-100 bus or the IEEE-696 bus....
12) How old is my computer?
13) How long will disk, tape, CD data last?
14)Why can't I get "access" to today's computer hardware like the "good old days" computers?
15) Why bother with S-100 computers, when the IBM PC blew them away years ago, and MS-DOS/Windows is so much better than CP/M, etc. etc.
16) I just bought a Heath or Zenith device - can you help me? (or whatever happened to Heath and Zenith?)
17) How do I get files to or from my S-100 system to my [Mac, PC/Windows, Linux] system?
18) Where can I get CP/M software (or CP/M) to run on my S-100 computer?
19.1)I'd like a copy of a manual. Why do you charge so much?
19.2)Why won't you provide just a schematic? Why must I pay for the whole manual?
19.3) Why do you restrict your customers from scanning and posting the manuals they buy from you?
LAST) Why are you complaining about my posts in comp.os.cpm?
To go to my S-100 home page click here.
To order S-100 stuff from me click here

Editorial: General requests for computers, help, discussion

The simplest inquiry to respond to are collector's requests to buy IMSAI 8080's or Altair MITS systems. If I have one for sale, it will be listed and described on my Web site. Check my S-100 home page for links to MITS Altair stuff and IMSAI stuff. They won't be cheap.

Generally speaking, my services are to supply you with the technology about your old computer, so that you, not I, can use it and maintain it and fix it. If that is not your interest or it's outside your abilities, I have little else to say, no offense. My previous heading on my S-100 Web home page was: "I let the manuals do the talking". I am not adverse to responding to specific questions, or to help someone with specific needs who has clearly exhausted other venues. But I need to know you did some "homework", and you have to inform me about your situation and equipment so I know what is going on. What you'll get from me will be in proportion to what you've done yourself.

For instance, I recieved an inquiry from someone who asked for help with his old S-100 system. He simply asked for "help" and said little else. I said most of what I offer is on my Web site - check specific questions in this FAQ - or is contained in my original manuals' collection from which I offer a copy service. Otherwise, like any busy person my time was limited and past a LITTLE discussion my time is not free of charge. In any event I'd need more information on what they have, and what they want to do with it, and their skills in working with it. He then asked if I could "simply" test his system's cards with my system to see if they would work, and if he could call me on the phone about them. I think he missed my point, so I have a longer explanation below.

Another common situation: someone wants "a working CP/M system" or "an S-100 hard drive system": but no specifics about what kind, or why, or what they plan to do with it. My reply is generally that what I have for sale, is or will be listed on my Web site, and it is as described. If you want it to be something else, or to do something else; that's up to you to consider specifics. Some of this is now discussed on my how-to CP/M Web pages.

About restoring old systems: I have a whole Web section about repair, restoration, and display of old computers, at this Web link.. I think it's important to preserve these system, and preserve knowledge about how to do that.

Finally, and I say this with no false pride, some people seem to be looking for long discussions and chat with me. My response is pretty straight about this: I do not confuse chat or discussion, with accomplishments and work done; or with good HARD THINKING, HOMEWORK, TESTING, REPAIR, PROGRAMMING, and so forth. I have yet to see a S-100 system talked into working. While discussion is useful and pleasant and informative in moderation, it must be followed by work to be useful and to produce results. I already provide access to manuals, hardware, and my own and other's writing on my Web site, and links to other sites and references. I provide my time to answer responses and to provide materials; often I say "here is where you can get more information". Chat does not replace reading books, manuals, and other information. Chat does not replace effort.

If chat and discussion is your primary goal, there are many Web-based discussion groups available about most every kind of vintage computer or computing subject. I recognize my attitude is very anti-21st-century, anti-UTube, anti-Twitter. That's not my worry, thank you.

So much for Herb Johnson: what have YOU DONE? What are YOU GOING TO DO? - it's up to you to determine what you want and what you will do with these old computers, not me. You can see that my general response is that you need to spend YOUR time, not mine in sorting out your needs and goals and wants, in resolving problems, in doing repairs. You need to explore resources already available - from me and from others - before asking for more from me. I don't consider conversations with me as the way you will go about this except to get some directions. I don't confuse conversation with accomplishment. My time in bulk is not free, as my time has value to me and to others. My time is my most precious resource - just as yours should be to you, I don't want to waste YOUR TIME either.

How can you determine what to do, what to have? What are my expectations of a reasonable request? What advice would I give you, if I gave advice? Read what's below. The information below is not my last word on what you might do or what I might offer, but it and the content of the rest of my Web pages, should provide you with valuable clues.

Herb Johnson

0) Where is the CP/M FAQ from comp.os.cpm?

There is a Usenet newsgroup (today they are called discussion groups) called comp.os.cpm. Check it out, search through the archived discussions, but start with its CP/M FAQ (frequently asked questions.) It may answer some of your questions. Check my list of S-100 Web pointers for a current reference to that FAQ. or use Google's search engine to find "CP/M FAQ". Regretably, as of year 2002 and at least up to year 2009, the owner of the site which supports the CP/M FAQ has not chosen to update it or make announcements about it in comp.os.cpm. For more information about the CP/M FAQ or comments, contact that Web site for more information or comments about the CP/M FAQ, not me.

Otherwise, read my FAQ and my S-100 site to get more useful information and keywords. Then use a Web search site (Google comes to mind) to search the Web AND newsgroups (discussion groups). Try a number of keywords; if you get too few "hits", remove some of the keywords. Google and other sites will give you access to YEARS of old messages from discussion groups that can be very informative; and access to many informative Web sites.

1) What is my S-100 system worth? Is there a market for it?

(Also check item 6).)
I understand the desire to know the value of your computer, but the market for old computers is very limited, there is no "blue book" for value, and it essentially depends on the interests of a small number of people. Anything I have to say on the value of S-100 equipment or how or where to sell it is in my contributions to the comp.os.cpm FAQ on this very subject. I'd say in general: look around the 'Net at newsgroups, Web sites, and auctions and take notes. I would NOT trust any "lists of prices" or values, certainly any that do not describe the source of their estimates.

1.1)Why is the S-100 world of any interest or value today?

Check this Web document for some details.

2)I gotta get rid of my S-100 system NOW!

3.1) I got this neat S-100 system, and I want to make it work (?). What do I do?

This usually means you want to run CP/M on it, maybe with a hard drive or (more reasonably) with a floppy drive. You may have docs and software, you may not. And, you may not know anything about CP/M, or how you would build your OWN "version" of CP/M for your hardware. CP/M is now discussed on my how-to CP/M Web pages.

S-100 systems were often used to prototype, or design, a computer for a specific application or use. In that case, your "system" may have NEVER run CP/M before. In many cases, S-100 systems did not use hard drives. Very old S-100 systems did not use floppies! Also, there was no "standard" S-100 system. Each manufacturer had their own set of cards; some manufacturers sold cards to upgrade or improve other S-100 systems, but often it was up to the BUYER to modify the software to adapt to those other systems. And some S-100 cards did not work well with other's cards.

But, there were other S-100 systems sold for business and commercial use that ran reasonably well and would require less programming and hardware knowledge from you. Those systems will likely have the disk drives (or at least the disk controllers) with them.

So, be explicit as to what "make my system work" means. These are not IBM PC's. What do you want to do with it, and what will it need? If you "just want a system", you are probably thinking in terms of what IBM-PC compatibles do, with floppy drives and hard drives and video. This is not what most S-100 systems did or do. Sorry.

You should make a complete inventory of your system before you ask ANY questions. That means a list of cards, disks and docs by manufacturer, model, year, and basic function (video, memory, serial, floppy controller, etc.). If you don't care to do this, it will be hard for anyone to offer specific help.

Look on my Web site for information on Dave Dunfield's support for reading and writing diskette images, using both native tools on a 8-bit system, as well as MS-DOS based tools called imagedisk. He also has some hard-sectored supporting tools. He also has a collection of boot diskette images for many 8-bit systems.

3.2) Where do I get more information on CP/M? on programming? on hardware? on S-100 cards? on old computers? on selling/buying (your choice)?

CP/M is now discussed on my how-to CP/M Web pages. Check the comp.os.cpm CP/M FAQ list and Google; and my own list of S-100 Web pointers Also, see what is being sold on newsgroups or auction or sales sites: you may see something you need. Also, check your local public library; your college library; your university engineering library. Old books on CP/M and sometimes on specific systems are still hiding there! (but as of 2002 many libraries have discarded these books.)

I am considering republishing my articles on S-100 as written in The Computer Journal. As of 2001 "The Computer Journal" appears to be out of business and TCJ is no longer available on the Web.

There are CP/M archival Web sites, and sites for old CP/M commercial software: a Google Web search will find them, or check my S-100 Web pointers page.. Check newsgroup/discussion group comp.os.cpm, for questions about assembly language or discussions of the history of CP/M. I will give some info about S-100 cards and answer direct questions. I can't chat a lot: I must manage my time and resources and I "let the manuals do the talking".

4) How do you find the time and resources to do this?

I support S-100 cards, supply cards and documents; and some support for 8-inch floppy drives (and a few other sizes). I also have a somewhat useful old Macintosh computer service, some SGI computers for sale, and some other odd computer stuff for sale.

I provide CP/M support on my how-to CP/M Web pages. But I do not provide much CP/M software and programs - others do that. I do offer some CP/M boot disks and such software as is needed to work with hardware. I occasionally offer systems for sale. I sell some S-100 cards, and some 8-inch floppy drives and cabinets. Some people are kind enough to sell or even give me stuff that I can resell. If you like what I do or my site, buy some stuff from me or offer me some stuff, so I can continue to "find the time" (i.e. money) to do what I do. But see my related comments below, and I presume you read my editorial above.

5) I'm interested in (your choice) but I don't want to spend much money.

6) I want to buy an (IMSAI, Altair). Do you have one? When will you have one to sell? Can you put me on your list? How much would one cost?

6.1) I want to build an (IMSAI, Altair) copy, replica, clone, etc. Can I do that from the documentation? Do you have the cards, parts, etc?

Check the Web for sites or discussion groups which sponsor new kits for old 8-bit computers. Check my list of Web pointers for kits and replicas. Many sites represent past efforts or dormant efforts, some sites are active.

If you have this in mind for your own project, I can be slightly helpful but not terribly helpful. But you have to help ME by being very EXPLICIT about your plans and goals. Keep in mind I simply don't know and probably can't guess what your intentions are. I don't know what your skills and knowledge are. And I don't know what you want this "copy" to do. So BE EXPLICIT, or say "I don't know yet". I've had inquiries for everything from building an exact replica down to nuts and bolts; to a simple box that looks cosmetically similar but has no functionality; to something in-between with functionality unclear even to the person asking for help! If you don't know much about these computers, er, you MIGHT want to read my site and these notes, and maybe buy a copy of a manual, before asking for my time and assistance.

The original manuals for these systems have information about the mechanicals as well as the circuits, as they included instructions for assembly, theory, and use as well as parts lists. I certainly can't say if they are complete to build a replica: they were only "complete" to build, maintain, and operate a complete kit in 1975. But they are more descriptive than manuals today. As for the digital hardware itself, please do not use 21st century standards to make decisions (or gripe) about 20th century computers.

6.2) Do you have any recommendations for someone who would like to purchase a functioning IMSAI 8080 [or MITS 8800]?

Regarding prices and sources, or for "collectable" questions, see my response above. I can't offer appriasials or assessments of present or future value.

Are you asking what could I recommend in terms of your use of an IMSAI or Altair? As I have no idea of your particular interest, time, budget or skills I don't know what to say to you. If "functioning" is the issue, I CAN say that a 30 year old computer will have or will soon have any number of problems which will need repair. Parts particular to the IMSAI or Altair may be hard to find. I do offer good copies of manuals and docs for S-100 equipment including the IMSAI 8080 and related IMSAI cards as per my site's descriptions. I may have some particular S-100 cards, ask for specifics. Someone will have to keep your system functioning, or get it to function: why not you?

As for advice or technical assistance, if you ask me brief and SPECIFIC questions I may be able to answer them but I'll often say "read the manuals", "check my site", "check the Web" or " post something in a Usenet newsgroup". I simply can't spend a lot of time answering emails at length, for free. As much as I'd enjoy a bit of conversation, I can't enjoy it if it overwhelms my time. (Also I hate to answer questions that can be answered by reading the manuals. They are a good resource.)

That said, there is a lot of info on my Web site, including a S-100 frequent questions page (FAQ), Web pointers page, and so on. I offer copies of original manuals for a modest price (which keeps me in business) But if all you want is a cheap IMSAI or Altair, we no gots. If you need technical support beyond some hints, or if you need actual repair work, I can quote commercial rates for such services but they are not cheap.

Are you asking "what can I do with a S-100 computer?" I can speak to use of S-100 systems for design of what is called today "embedded computers". Many products today still use 8-bit processors. So an S-100 system is not unreasonable as a development platform for 8085 and Z80 based applications. But many are interested in these systems for historic reasons; or personal reasons from use of them decades ago. See my Web page about the history of CP/M, to see what it was like before personal computers, and what they did in the beginning.

The point of the S-100 world is that it was a place where people could test and experiement with a variety of S-100 cards which performed many different tasks; and to develop specific, custom systems for specific activities; AND to have a flexible hardware system to keep up with advancing technology. You can STILL do that with any S-100 system, old or new, subject to the limitations of the S-100 world of not-quite-standard cards and older technology. People today are STILL interested in doing this kind of experimentation, either for personal use, for design and development for products, or because this is what they did in the past as a profession. So interests in S-100 systems are a mix of interests in engineering, hobby work, historic preservation, and nostalgia.

6.3) Where did the names "Altair", "S-100" come from?

Check this Web document for some details.

7) This is not an S-100 item, but I'm looking for (your choice) which was built in about the same period of time. Do you have one or know of where one is?

8) Could I have a list of all your cards? How much for (your choice)? Do you have this card?

9) I want to read CP/M disks from my [previous CP/M system] on my PC Windows system.

Some of this is now discussed on my how-to CP/M Web pages. Look specifically for Dave Dunfield's support for reading and writing diskette images, using both native tools on a 8-bit system, as well as MS-DOS based tools called imagedisk. He also has some hard-sectored supporting tools.

Prior to year 2002, a company called "Sydex" offered MS-DOS programs called "22DISK" and "ANADISK" which could read CP/M formatted disks. They and others still offer such programs but for a fee. Please read the section on adding 8-inch floppy drives to DOS/Windows systems for information about those programs. But briefly these can only read CP/M SOFT SECTORED diskettes and convert the CP/M files on those disks to MS-DOS files on your PC/Windows system. Note that this only READS FILES, it does not convert the information in those files from one word-processing format (WordStar for instance) to something a PC can process (Word or Word Perfect for instance.)

Old CP/M disks are usually soft-sectored, but very old ones may be hard sectored. "Hard sectored" means the diskette has holes to mark each SECTOR, not just a hole to mark the start of each track (called the index hole). Check this section on hard sectored disks for details. For some DOS/Windows based hardware to read non-DOS disks, here is a link to some hardware products I have heard of. Check my list of S-100 Web pointers for possible links.

In any case, you might better find someone with your specific matching model of CP/M system, or get help to revive your old CP/M system. Your best bet to do that may be to pour out your story on the Usenet newsgroup comp.os.cpm and hope that someone knows your system and can either help you fix yours, or will offer to read your disks. Or Google search PREVIOUS comp.os.cpm postings and see if someone offered help previously. Or, do a Web search for sites which have more info about your old CP/M system by brand name and model.

Otherwise a Web search on "media conversion CP/M" will find companies which will read ANY format and provide data conversion services, at commercial prices that you'll likely wince at. I do not offer such services as they just don't pay out in practice.

9.05) I want to run CP/M programs from my [previous CP/M system] on my PC Windows system.

Check my S-100 Web links page for sites which have CP/M emulators for MS-DOS, Windows, or Linux. Also check my CP/M how-to page for discussion of emulators.

9.1) I want to read hard sectored CP/M disks on my PC Windows system.

Look specifically for Dave Dunfield's support for reading and writing diskette images, using both native tools on a 8-bit system, as well as MS-DOS based tools called imagedisk. He also has some hard-sectored supporting tools.

Old CP/M disks are usually soft-sectored, but very old ones may be hard sectored. "Hard sectored" means the diskette has holes to mark each SECTOR, not just a hole to mark the start of each track (called the index hole). Hard sectored disks ARE NOT READABLE by any typical floppy disk drive and controller. It is not enough to use "22disk" as the physical hardware of any PC cannot interpret the sector holes at all regardless of what programs you use. You will need an add-on card inside the PC, connected directly to the internal or external floppy drive, to read hard sectored disks; plus programs SPECIFIC TO THAT HARDWARE.

To determine if your disks are hard sectored, you can examine your diskettes visually. Take a diskette and by hand rotate the inner media (some call it a "doughnut") around within the outer plastic sleeve. Watch the index hole through the envelope's hole. If you see only ONE hole per rotation of the disk then your disks are soft sectored. If you see several holes they are HARD sectored. Information about hard sectored disks and reading them on PC's can probably be found by a Web search on those terms, leading to sites which offer hardware that may be able to read them. Here is a link to some hardware products I have heard of. Check my list of S-100 Web pointers for possible links. read these notes in my floppy drive information Web page. In 2010-2012, some work was done with hand-punched diskettes for Northstar systems. Read my notes about this.

9.2) I want to read old MS-DOS [unusual format] disks on my PC Windows system.

Some people used unusual formats or diskette drives on their older MS-DOS systems - relevant to my interests, the Heath/Zenith Z-100 for instance. Now those systems are either failed or lost, yet they have a bunch of diskettes that they now want to read.

You may get some results using the software tools I mention above to read CP/M disks. The "Anadisk" program will at least inform you about disk formats. In some cases it will copy disks. As for reading 8-inch diskettes, check my FAQ response about 8-inch floppy drives below. Also, old MS-DOS versions supported 8-sector formatted 5.25 inch diskettes; newer MS-DOS versions may not. You might try obtaining an old MS-DOS like 3.3 and see if you can read and write from 8-sector to 9-sector disks.

Look on my Web site for Dave Dunfield's support for reading and writing diskette images, using both native tools on a 8-bit system, as well as MS-DOS based tools called imagedisk.

But your best bet may be to resurrect or obtain a duplicate of your old system hardware and software. You may have to connect that system to a "new" DOS/Windows PC via a serial cable and do file transfers. Check my FAQ response about serial transfers for more information.

9.3) I want to read MS-DOS disks on my CP/M system.

"Some years ago, I wrote a thing called MDCFS (Minimal Dos Compatible File System) - this is an absolute bare-bones file system which allows you to read or write a file on an MS-DOS format floppy disk. It's written for my own MICRO-C compiler, however iirc it's fairly standard. It was designed to be used without any operating system at all (you supply sector read and write functions). I believe it is still available in the EMBEDPC.ZIP archive which is located on my commercial site (www.dunfield.com)." As of 2020 it's available on the classiccmp.org Dunfield Web site

Likewise, Lee Hart posted: "[PCSWP05.ARC] may be a version of the CP/M SWEEP program, modified to read/write PC DOS format disks. I bought a version of this modified for the Heath H8/H89 by Peter Shkabara called "CPC". Like SWEEP, it lets you read/write DOS format disks and select files, view, print, copy, delete, and rename them. He included a PCFORMAT program as well that will format DOS disks on an H8 or H89 with the Heath soft-sector controller. Peter is still around, and has these programs and perhaps the source for them as well."

Subsequently, I found PCSWP05.ARC is on the Walnut Creek CP/M CD-ROM under "cpm/beehive/utilitys/". Search the Web for this file by name or for the Walnut Creek archive.

9.4) I want to read (odd format, CP/M) disks on my Windows system.

Also look at my response to a question about using 8-inch drives on Windows systems. Many of those tools (hardware and/or software) are useful for working with 5.25 inch diskettes, particularly from the CP/M world.

There are a number of schemes available to read non-MS-DOS 5.25 inch or 3.25 inch diskettes on Windows systems, in addition to the methods described above for 8-inch drives. There is a program and a bit of hardware called "Disk2FDI" which is described at this Web page. It uses a PC and a cable between a 5.25-inch floppy drive and the parallel port, and is said to be able to read Apple II and Commodore diskettes. A trial version is free to read only; there is a registration fee to get the registered version, from Europe.

I discuss other tools and Web sites for dealing with CP/M diskettes, on my Digital Research CP/M Web pages. Specifically check this Web page, which includes discussions of CP/M emulators (to run software) and the work of people like Dave Dunfield, who offers bootable CP/M disk images and software to read and write such disk images. Look at my discussion of Dave Dunfield's support for reading and writing diskette images, using both native tools on a 8-bit system, as well as MS-DOS based tools called imagedisk. He also has some hard-sectored supporting tools.

9.5) where can I find someone to read my 8-inch or CP/M or ??? diskettes?

10) I want to hook 8-inch floppy drives to my PC / Windows / Linux system...

If you are not a technical wizard, please read my answer to a similar questions first. For reading 5.25 inch disks in odd format, read this response and also look at this response specific to 5.25 inch drives.

Some of this is now discussed on my how-to CP/M Web pages. Look specifically for Dave Dunfield's support for reading and writing diskette images, using both native tools on a 8-bit system, as well as MS-DOS based tools called imagedisk. He describes ways to connect 8-inch drives to a PC.

Also, Please check this floppy drive technical page for more information.

You will need a number of things to do this. 1) either an adapter from the 50-pin cable on the 8-inch drives to the 34-pin connector on the PC compatible's floppy drive controller; OR a floppy drive I/O card to run 8-inch drives. 2) Software to operate the drives which will also interpret the CP/M (or other operating system files) format on the disks on that drive, so you can copy those files to and from your PC/Windows system. 3)Additional software to INTERPRET the files recovered from the 8-inch floppy disks, such as changing from one word processor's format to something more current. I explain some of these considerations in another question and answer.

Anything I offer for PC/Windows/Linux systems would be on my floppy drives Web page. For information on connecting 8-inch drives to typical PC/Windows floppy disk controllers, check the docs contained with Sydex's 22DISK and ANADISK (see below); and check the CP/M FAQ

Prior to year 2002, a company called "Sydex" offered MS-DOS programs called "22DISK" and "ANADISK" which could read CP/M formatted disks. They included documentation on how to attach 8-inch drives to PC-type floppy controllers, running on old (pre-Pentium, MS-DOS based) PC-compatibles. The 22DISK and ANADISK program suites provided a very comprehensive list of 8-inch and 5.25 inch CP/M diskette formats, which will help you read and write not only many 8-inch diskettes, but many 5.25 inch diskettes for CP/M use. ANADISK supported copy and format of non-CP/M disks if you have an original disk: it had a feature to copy bit for bit most such disks.

Versions of those programs were distributed in online MS-DOS archives at no charge for evaluation; early MS-DOS "shareware" archives may still have those versions. Sydex subsequently sold some software rights to another company which offers (as of 2002) some related products on commercial license terms. For information on the current status of Sydex and their products, check this discussion on my S-100 Web links page.

The programs above, or any other such programs, require the CORRECT connection between the PC's floppy controller and the 8-inch drives. Some sites offer directions as to how to connect 8-inch drives by building a simple adapter. These adapters have limits.

In 2002, "D Bit" in Mass USA offers a small card called FDADAP to connect 8-inch drives to a PC's floppy disk controller cable. Check his site for more info, but his software is limited to some DEC (PDP-11) support and some general utilites. (As of late 2004 his product is still available. Mention my site if you go there.

Another company, Individual Computers, in Germany, manufactures a "Catweasel" floppy disk controller, available in the USA. It's a complete PC card (PCI bus card) and Windows software package for reading and writing a variety of disk formats, mostly 5.25 inch disks, including some hard sectored formats, and also some discussion of 8-inch drives and formats. Do a Google search on this product by name to find the Web page for details or discussion from users of this and other products for reviews. Check my floppy drive discussion page for current information.

One final but important point. Reading a CP/M disk on a Windows PC is only the FIRST step. None of the programs above will CONVERT DATA; they will only read old files from old disks. To USE THE FILES AND DATA you may need to CONVERT that data. For instance, if you have old Wordstar (CP/M word processor) files, you need to convert those files from that format to the format of your Windows word processing program. Check the relevant programs on your Windows system to determine if they can convert files; otherwise you may have to write programs to do that conversion.

If you want further assistance from me to read your old 8-inch disks, and to make sense of your old computer equipment, I may be able to offer professional services at a professional charge rate. For hobby and personal use, beyond a few suggestions and hints (and the resources already on my Web site) you may be able to get some help from other hobbyists via Usenet newsgroups (discussion groups) appropriate to your old computer's software, operating system, or hardware.

To return to my S-100 home page click here.

10.05) I want to read 8-inch floppy disks on my PC / Windows system...

For more technical discussion, read my response to this similar question about 8-inch drives.

Here's a version of a typical question: "I am working on preserving and converting some 8" diskettes to a modern format. I am new to this and would really appreciate any help. I hope someone knows of a reliable source for a old floppy drive that can read these disks. I don't currently know what system the data was written in. Also, could someone point me in the direction of the best way to convert this data."

The short answer is that you've provided so little information that anyone who COULD help you from their own, personal or hobbyist resources, would not know enough to offer to do so. More information equals more help. Most likely, you'll have to pay a commercial company to do this for you, to sort out what you have on your disks, if they can. But if you have the same information on printed documents, it's cheaper to hire a kid to type it into Microsoft Word for you.

To get help, you have to identify the SPECIFIC COMPUTER system these came from; and what operating system it was running. You might need even more information about that prior system, including what software and hardware was used to write those files. Any information you have at all will be helpful: as it stands now with what you've said, you are in a very difficult situation, which would require an experienced technician with access to 8-inch drives and old-school experience to resolve for you. Or, pay a company which does this kind of work all the time.

In any event, buying an 8-inch drive will do you no good, most likely. An 8-inch floppy drive won't "plug in" into your Windows PC. There is currently no simple, plug-in-and-go, hardware and software system you can plug into a Windows PC to either connect to an 8-inch floppy, or to read whatever is on that floppy. There are some partial solutions, which informed technical people can use to make it work. You'd have to get "lucky" to find a technical person who has this capability AND who would help you for modest cost.

Otherwise, there are commercial companies which read old diskettes and convert data or text files, for rather expensive fees (if your interest is only personal). A Web search will find them. I don't use them so I don't make recommendations.

10.1) I want to hook a 3.5 inch drive to my 8-inch floppy drive system; or a 3-1/2 inch drive to my 5-1/4 inch drive system, etc.

Read the FAQ item on 8-inch drives above. for some clues. Please check this floppy drive technical page for more information.

The basic problem is that, even if a 3.5 inch floppy drive is magically wired up to an 8-inch floppy drive controller, the FORMAT of the resulting 3.5 inch disk is, nontechnically speaking, screwy. I do guarantee that it WILL NOT BE READABLE BY A ORDINARY MS-DOS, WINDOWS, OR MAC OPERATING SYSTEM. It is possible (see the FAQ item I mentioned) to obtain programs that MAY be able to read it. HOWEVER, it is possible that some old 8-inch floppy controllers may create disks that are NOT READABLE AT ALL under those schemes. To make a determination requires specific hardware and software information about the system in question. The CP/M FAQ has some comments about wiring up 8-inch 5.25 inch and 3.5 inch drives. I also have a document about various drive and diskette types on my Web site.

10.2) I want to run floppy drives (CP/M) on my S-100 system...

10.3) I want to run hard drives on my S-100 system...

See my response to a similar question about specific drives of differring sizes.

This may not be easy, as there were no common standards; drives varied in size, capacity, and even the interface (connections). Also keep in mind that some S-100 systems were sold BEFORE hard drives or even floppy drives were commonly available! The earliest S-100 systems used punched paper tape for file storage, or later audio cassettes. So some S-100 systems NEVER used hard drives or floppy drives. Also keep in mind that some S-100 "systems" were simply collections of cards from several manufacturers; you may have to do a lot of software and hardware work to make some controller "work" with your unique system.

Here's an approach that I think is reasonable: you may disagree of course. First, if your system's cards is all of ONE brand, see if that manufacturer provided a floppy disk controller or hard drive controller card or cards. Then see if you can obtain those cards and their software. Second, consider some OTHER brand of controller card and software, and see if that software and hardware may be suitable for your system. (Check my lists of documentation to see who built what.) Third, build something up from scratch or adapt something recent. Alternatively, use a PC to upload and download software to and from your system, via some serial port link, and save your files on your PC. Finally, you might just use programmable ROMS (EPROMS) on your system, on a S-100 PROM card.

S-100 controllers for hard drives or floppy drives varied in size and complexity in the 20 years of S-100 systems; some may be more useable today than others. The first controllers were ancient S-100 cards (sometimes a pair) with lotsa small chips or even their own microprocessor. These are very hard to revive. Later was a simple "interface" card with several parallel ports, which "talked" to a SASI or SCSI controller card which actually ran the drives: these controllers were made by Everex, Western Digital, and others and can be found on many old computers. Later still, the S-100 manufacturers were able to build their own S-100 controller cards with their own software: check their manuals and docs for details. Keep in mind that the older the S-100 hardware, the older the drives's technology: that may mean using MFM hard drives and 8-inch floppy drives, or 5.25 inch hard sectored diskettes, and so on. These older technologies can be hard (or expensive) to find and hard to keep running.

CP/M software for many S-100 computers may be available from the "usual sources"; check my list of Web pointers and of course my S-100 Web site for specifics. I have some floppy controller hardware and software for S-100 systems in my SD Systems Web page which you may be able to adapt, and in fact that is one of my efforts on that page. In any event, some of the software and hardware issues about running floppy disk drives (and by extension hard disk drives) on old processors is discussed on that Web page. I also have a technical page on floppy disk drives that may be informative.

Some time ago I was the first to import into the USA the Tilmann Reh GIDE interface card. This card plugs under a Z80 processor and provides an IDE drive interface. Only Z80 cards can use it, but the principles of operation may apply to other systems. Check my GIDE Web page to get more info but I no longer offer it. But it is EASIER for slow processors to operate IDE hard drives than any of the older hard drive OR floppy drive technologies.

10.4) I want to replace my MFM hard drive with an IDE hard drive...

Also see my answer to question 10.3, about adding hard drives or floppy drives to an S-100 system.

There was an April & May 2007 discussion of MFM "emulation" in comp.os.cpm, where I participate. It was noted that there WAS a MFM to IDE product, but it was a few thousand dollars. (Check there for details.) Seems to me that one reason it is that high, is that it takes some bit of effort to support the variety of potential uses for such a product. Each user would likely need some degree of support, to adapt this "emulator" to their particular situation, I would anticipate. Those who really need an MFM replacement, to keep production equipment going, will pay accordingly.

The drive issue as cast in comp.os.cpm was about replacing an MFM drive in a S-100 system. It was suggested the owner use an IDE card of some sort, and write a driver. In some number of cases, it's more reasonable to replace the controller and adjust the software. Many older systems allow that, if you can write software, if you have info on the operating system; or if it supports alternative hard drive controllers.

The point of S-100 systems with a standard bus, was that you COULD replace and upgrade as needed. At least the hardware did not stop you from doing so. That concept spawned a computer industry from 1976 through the 1980's. The IBM PC, to compete, HAD to offer 1) a bus and 2) clear means to add to that bus - because S-100 and other systems set that standard. (In the minicomputer world, DEC set a similar standard as did other manufacturers.)

I imagine that, for some owners of old computers which had very little support for any changes at all, the above sounds VERY BORING. It's fun to imagine that you can simply "plug something in" and - ta da! - it "works". Well, in the S-100 days, the point of the S-100 bus was that it DID provide "plug-in" capability - but no guarantees that it will work merely because the card has 100 pins and fits the chassis. But in general, one also had the tools needed to adapt a "new" card as needed. Similar logic applied to the DEC PDP-11 world. That was the WHOLE POINT about a standardized bus, a documented operating system - expandability! A S-100 system with native, original cards was exceptional: over 100 companies made S-100 boards.

An IDE interface for S-100 or any Z80? - dirt simple, the IDE drive does all the work, just a few simple chips will do it (Google "GIDE"). A MFM to IDE? You need what amounts to a computer on a board, and you can't do it with 1970's logic, you might succeed with 1980's logic, but it's less painful to do it with some modern, small, generic processor card. Handing serial data at a few megabits a second is now doable in software on 16-bit or 32-bit processors (or a programmable logic chip) at a few tens of megahertz.

The point? As I see it, if you are "into" old computers to show them off in original condiiton, then all this talk about "emulators" is moot. Pay $$$ for the last unused MFM hard drive and run it only on exhibit day. If you are in it because you can "dig into" it, then adapt some new hardware to old and start writing some CODE. If you are in it for "use" only, then you depend on others to keep providing working hardware: that, and your budget.

11) Please describe the details of the S-100 bus or the IEEE-696 bus....

I have a list of S-100 bus signals for various S-100 systems, you can look at that. A short description of the S-100 bus is "what if I took all the Intel 8080 processor signals and brought them out to a bus?"; so a review of that processor's data sheets would be informative. Also any documents on S-100 CPU cards would be informative; I have a few of those on my site, check my lists.

The IEEE-696 standard which describes a later version of this bus may or may not be on the Web. IEEE standards are copyrighted by the IEEE and copies may be obtained from them. They may not have this standard listed by name (IEEE-696) as it may be considered obselete. Do a Web search. The standard was also published in the IEEE Computer magazine many years ago. A search of that magazine's index may find the article which was a preliminary version of that standard. Also a copy of the IEEE-696 standard, and some CPU schematics and a bus description, were published in a book by Dave Bursky, "The S-100 Bus Handbook", Hayden Book Company, ISBN 0-8104-0897-X. Other older books or articles with the words "S-100" or "IEEE-696" may also have the standard or its predecessors included.

12) How old is my computer?

13) How long will tape, disk, CD data last?

See my Web page on floppy drives and media for more details.

This subject comes up every time some CP/M archive on the Web vanishes, or there is some discussion of data media. Of course some CP/M original media is 20 years or more old, so it is relevant. The issue in many cases is not the degration of the media, but loss of old technology and software to READ the media. A reasonable strategy is to copy data to "current" media every few years to avoid both media damage and obsolscence. A Web search on particular media and studies of reliability will find references to failure modes; I won't list them here but I'll review the issues briefly by media.

Various studies of magnetic tapes suggest that tapes lose data in many ways over the course of years, particularly if the tapes are idle and stored in environments with varying temperatures. This is less true for diskettes, but data can still be lost over periods of years and decades. All magnetic media are damaged by magnetic fields of course.

CD's are either user-recorder (CD-R, CD-RW, etc.) or are "pressed" like audio CD's. Most CP/M data did not make it to commercial pressings of CD's. Various studies suggest that CD's can fail by oxidation or other physical damage to the aluminum reflective coating. Periods of a few to several years are mentioned.

Web archives are only as reliable as the good will and fundign of the people sponsoring the sites. Some public-domain sites of long standing in the 1990's went away in the 00's as funding for their public (university) institutions has declined with the bursting of the Internet "bubble". Check my S-100 Web pointer page for links to some of these archives.

14) Why can't I get "access" to today's computer hardware like the "good old days" computers?

*>Sadly, it's because we're so removed from the underlying hardware.
*>
*>Computers used to have real "front panels" with toggle switches and displays,
*>usually hard-wired to specific registers and status lines.
*>Now you're lucky to have any firmware assist for debugging the system...
*>...folks clamor for blinking lights again,
*>thus all the PCs with light-show stuff, Linux's LCD projects and such...

15) Why bother with S-100 computers, when the IBM PC blew them away years ago, and MS-DOS/Windows is so much better than CP/M, etc. etc.

Incidently, DR-DOS still survives today (in 2003) as a licensed product line after several asset sales from company to company through the decades. My links page will find current info. Many companies which offer self-booting products use DR-DOS as an easy-to-distribute operating system.

16) I just bought a Heath or Zenith device - can you help me? (or whatever happened to Heath and Zenith?)

If you recently bought a Heath/Zenith device, chances are it is from China. Look at the box it came in, or look for similar products back at the store you bought it from, to see who to contact. If I have more info about this, it will be on my Heath and Zenith computers Web page.

17) How do I get files to or from my S-100 system to my [Mac, PC/Windows, Linux] system?

(also see my related question about reading CP/M diskettes on a PC/Windows system.

Sooner or later, most people who own an S-100 system need to transfer a file to or from a DOS or Windows (or Macintosh or whatever) computer. A Google search of comp.os.cpm "groups" will find a discussion of this very topic that last occurred in early 2003. It's an old topic. Most people who need to establish serial file transfers to or from a CP/M system (or N* DOS system) of ANY sort end up doing something like this:

1) get a SIMPLE file transfer program onto their CP/M system. This can be done by TYPING IN the hex codes or source of a simple recieve program, which can be found on one of various CP/M archives on the Web; or found in an old magazine article or book. CP/M (or HDOS or N* DOS) generally have programs which can accept either assembler, BASIC, or can take Intel Hex format files (used by most 8080/Z80 assemblers) and convert them to executables. Or the "debugger" (DDT in CP/M) can accept hex codes and create an executable program (.com) file. READ THE MANUALS for your operating system for information about that business.

2) Usually a PC running MS-DOS or Windows is at the "other end" of this transfer. Shareware programs like Procomm or QMODEM, are available from ancient MS-DOS archives; and Hyperterminal in Windows. These provide comm program file transfer capabilities. As for the cable to wire the two machines, if "transmit", "recieve" and "handshake" are unfamilar terms to you, the simplest thing to do is to describe your two systems and ask someone who knows both systems to build a cable for you.

3) Use the SIMPLE file transfer program to copy over a more ELABORATE communications program, preferably one that uses ZMODEM (or YMODEM or XMODEM) "protocols". A Protocol provides for error checking and resending of data: that is important for binary files in particular to guarantee an exact copy is transferred.

An even older solution is to use "Kermit"; a Web search will find the Kermit archives and support site - the rights to Kermit are still actively held as of 2009, it's NOT "public domain".

18) Where can I get CP/M software (or CP/M) to run on my S-100 computer?

Long ago, CP/M owners collected programs and distributed them on diskettes, usually through computer clubs. Businesses offered collections as well. Later they were put on CD's. Collections were also offered online, initially by universities, then businesses, and later by individuals on their own Web sites. Today in 2006, most CP/M collections are online at various sites, available from individuals or a very few companies. Search the Web, or check my list of CP/M Web pointers for links to those archives and services, including whatever I have to offer.

I also have an archive - a library - of S-100 hardware manuals, from which I offer copies of documentation for a per page fee. Some of these manuals have software, mostly to support hardware or operating systems like CP/M. In 2005 there are a number of Web archives of CP/M software. A Web search for "CP/M software" may well find them. I offer a CD-ROM of a classic re-archive of CP/M software called the "Walnut Creek CP/M CD-ROM". Check this link for details.

19.1) I'd like a copy of a manual but why do you charge so much? or anything at all?

A subset of this question is "Can you give me just the schematics?" follow this link for the answer. Another question is about my alledged policies about others posting "my" manuals; follow this link. There may be additional discussion of my services on my S-100 Web page. Current prices for my manual services will be on my "ordering" Web page, look for links to that page in this document. Regarding copyright: as I am not a lawyer, I have no comments about those issues, I have no comments about any "rights" or "policies" other than what I've said on my Web site and in this FAQ.

19.2) Why won't you provide just a schematic? Why must I pay for the whole manual?

I generally don't offer just schematics: I offer the whole manual at a standard per-page service fee plus postage and handling. If you need an explanation, it amounts to the fact that your payments supports my services; and a complete manual gives you much more information than a schematic. So we've priced our services to reflect the effort and costs of archiving AND providing whole manuals by the page, not selected pages. The charges for a schematic would have to "cover" the costs of not only the whole manual, but my time in servicing your request and order. The most reasonable resolution of this is to offer the whole manual, and charge proportionally to the costs of storage and reproduction - by the page. Discussion of my manual services are at this FAQ item.

19.3) Why do you restrict your customers from scanning and posting the manuals they buy from you?

As I am not a lawyer, I have no comments about any issues involving copyright, so I have no comments about any "rights" or "policies" involving my services other than to respond to this INCORRECT RUMOR. Discussion of my manual services are at this FAQ item.

Last) Why are you complaining about my posts in comp.os.cpm? (Trolls?)

*>From: hjohnson@myemailaddress (Herbert R Johnson)
*>Newsgroups: comp.os.cpm
*>Subject: Re: OT complaints about OT [discussion]

*>(Herb Johnson) wrote in message (whatever):
*>> 
*>> Sir, with all respect and consideration: if you want a discussion of
*>> [something irrelevant to CP/M or otherwise far from that topic] perhaps you'd
*>> do better to obtain a Web site, post your material on that site,
*>> and solicit discussion of it from there.....

In article [whatever@posting.google.com], thisguy@somehere.com wrote:
*>OK, Herb, please explain the differences between your concerns above
*>and the following (since you _blatantly_ violate all of your espoused
*>concerns in the [following] SPAM): [a copy of my generic announcement
*>of my S-100 services and hardware for sale]....
*>

See this document which describes the nature of trolls and something about such posts in Usenet newsgroup comp.os.cpm. Briefly, a "troll" is someone who posts obnoxious messages just to engage others in some kind of argument or discussion - ANY discussion will do. Consequently, if no one posts in reply, they will go away; if you post ANY reply they are "fed", and feeding them encourages them, and other trolls, to post.

To return to the S-100 stuff click here.

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