Saturday, September 26, 2009
Hi again !
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Just to get any “legal issues” out of the way first, since we are in such a litigious society that can inhibit the free flow of info between helpful people of “goodwill” –
DISCLAIMER – as with all my posts, publications, information provided, etc. -
I can have no liability / expense in any way and in any form for what I voluntarily provide to you or anyone else, even if requested.
It is offered in “good faith” and “as is” from the information I have available to me at the time it is provided.
Use it at “totally your own risk.”
If you do not agree with this, then just do not use this information.
Also check my other disclaimers on this site, my web site, my books, etc.
I have not heard of any such issues developing, but we all have to be very careful in this regard.
Keep in mind that there are certain hazardous aspects, especially electrical, with such projects and computers.
Also, I do not know what your specific technical, experience, training, abilities, etc. are.
If you do not feel comfortable with starting any of these projects, then try to find and hire someone competent and trained in these areas to do it for you.
Also, these older computers may have certain issues just because of their age and because you may not be aware of how others may have used, treated, modified, etc. them.
In addition, there is always the possibility of unintended and even unknown consequences depending on many factors.
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Erik may even want to include a similar disclaimer on this web site for all posts.
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That said, moving on, if it is still an option.
Welcome to the “world of vintage computer troubleshooting !!!”
It can be a very challenging intellectual exercise – like a crime investigation !
1] From the other thread you have on the Tandons, glad to hear they are working ok and it is just the Kaypro main board you mention is the issue.
2] Many times in troubleshooting, it is initially best to use the “KIS” principle – “keep it simple!”
3] A] So I assume you checked all the connections / cables to the main board, especially at J6 where the disk drive cable is attached to the main board. Also, I assume you checked all the connections to the disk drives and the cables themselves.
B] Like with the chips, some corrosion and / or bent pins can be issues.
C] Wires & cables, especially the plastic insulation, besides the connectors themselves, can deteriorate also over 25 years.
D] Also, any cracks in the main board can damage the traces & connections.
4] A] Swapping “good” parts for questionable parts is another useful strategy
B] So sounds like from your latest post you have two [2] main boards now and both do not work with the disk drives in your Kaypro, when you swapped them. Do either of them or both work in a known working Kaypro? I believe in another post you said you had a friend who had a working Kaypro.
5] You may want to just initially pick a few of the chips that are the “most likely issues” to check and possibly replace, if you can find new or working ones –
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NOTE – YOU SHOULD MAKE SURE YOU ARE GROUNDED TO MINIMIZE ANY STATIC ELECTRIC ISSUES WHEN YOU WORK WITH THE CHIPS AND IN SOME OTHER AREAS – A GROUNDING STRAP IS VERY USEFUL – E.G., RADIO SHACK HAS THEM AMONG OTHER SOURCES – YOU COULD EVEN MAKE YOUR OWN POSSIBLY, BUT THEY ARE INEXPENSIVE – YOU MAY ALREADY KNOW THIS, SINCE YOU SOUND LIKE YOU HAVE SOME TECHNICAL EXPERTISE FROM YOUR POSTS
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6] Basically, there are two [2] main chips that can affect the drives – both are in the lower right corner of the main board, as you look at the front of the Kaypro.
At U82 – the floppy disk controller FD1793 – it is a large chip - if it is the 1797 version, it may have issues
At U 88 – FDC 9216 data separator – it is a very small chip.
7] The 1985 book you have by Williams is the best I have ever seen! He has a picture of the main board on page #77 and notes the 1793 chip with respect to swapping it out with a good one.
8] A] The 1793 chip cost about $80 in the 1980’s he notes, so replacing one to see if it was the issue was not very attractive then. New Kaypros cost around $2000 [in 1980’s dollars – multiply by about 2.3 for today’s approximate dollars] at that time and main boards about $300 - $400, with some credit for the old one.
B] Few can realistically diagnose main board issues and actually fix them, especially today with respect to such old technology, so that is why many just suggest replacing them then and now.
C] But today, such working main boards may be very difficult to find, although one of the responses to your post did find one on eBay.
9] Microcornucopia said the cost of this chip was about $35 in 1985 in an article on troubleshooting such issues. They also noted that Kaypro got a lot of “flaky” SMC 9216 data separators that caused a lot of issues.
10] But I could not currently find these chips as replacements at Jameco and Mouser.
11] You could do a post on this web site for them and join Dave’s Dunfield’s email list at
www.classiccomp.org, along with other sites. Some very knowledgeable Kaypro people regularly post on Dave’s list about Kaypro issues, as on this site. A Google search may turn up some other even newer active sites as sources for old chips and Kaypro information.
12] Chips from another working Kaypro, if you can get one, could be used to swap in to see if either of these chips are indeed the specific issue.
13] Among some of my computer related publications, I even published a short note in Micro Cornucopia in 1987 on the 1793 chip that I found was also an issue with working drives, when I upgraded our six [6] Kaypro II /4 ’ s to Kaypro “ 8 “ ‘s, according to Micro Cornucopia information and parts.
14] Of course, the large Z-80 chips may be issues also –
At U54 & U72 - the two Z-80 PIO’s
At U63 – the Z-80 CPU – naturally
At U70 – the Z-80 SIO - possibly
These are still only a few dollars at Jameco.
15] A] From info you gave on U43 & U47, it looks like you have a “real” 1983 Kaypro II. It was good you knew to list these and got the Williams book. Shows you did some “homework !”
B] U47 - Monitor ROM 81-149 – but does it have a “C” after it – stamped on with what may look like a rubber stamp – it may be in red – it may be about ½ “ in size –
A & B versions may have issues
C] U43 – Character ROM 81-146 is correct for your main board.
16] Also check the main board on the back side near the serial port – it should say
81-110 – and a “ B1 ” might be after the 5 digits – it is designated as an obsolete board, but many such Kaypros have it and it can work – mine do ! However, it is difficult to get to this section of the board – you even have to lift up or remove the copper colored metal shield on the back after you remove the main board.
17] The 81-240 boards usually have it noted on the front of the board at the lower right corner [e.g., page #77 in Williams book]. According to the Micro Cornucopia upgrade booklet, if the chip at U47 was an 81-232 and not 81-149, then you would really have a Kaypro 4. These could easily be upgraded to Kaypro “8 ‘s ” by just adding the Micro Cornucopia chip. Kaypro II’s were more complex to upgrade.
18] CP / M version to use should be 2.2F for both of these boards.
19] You may also want to download the free technical manual for Kaypros at
www.bitsavers.org. Since you are so committed to Kaypros and seem to have some technical background, you should find it very helpful – schematics, diagnostics, test methods, etc. Many more details are available on this bitsaver site on this vintage computer and other sites, besides a Google search, naturally.
20] Dave has all the issues of Micro Cornucopia. If they are ever made available, like bitsavers is doing, they can provide a great deal of more specific information on Kaypros. Lists of authors and topics, about 400 pages, were recently referenced on this
www.vintage-computer.com site as free downloads. Many other topics on computers of that era were covered, besides Kaypro however, in Micro Cornucopia.
21] I disposed of my issues many years ago regrettably!
22] I was surprised you did not get more responses to this post!. Maybe the others missed it, especially those who responded to your Tandon posts.
23] All this is only a start – but may help. Please share your results, so this “thread” can be helpful to others who may now or in the future be in the same or similar situation.
24] I have done many Tandon drive fixes / alignments, so just be thankful you have someone to do it for you, in case you need it in the future. Besides all the tech info, you need special tools, parts, software, patience, temperament, etc. to really do it right / completely and be successful.
25] Again, there are many posts on Kaypro issues on this site and Dave’s already. Therefore, a search can be very worthwhile, so you and responders are not “recreating the wheel” of the same requests / information over and over again.
26] A] You can search under “Tezza” [I made the mistake of typing “ Y ”ezza in my post to you earlier] and his Kaypro issues around the 2008 Christmas / New Years holidays. It was a very popular and big thread with many specific details that may be useful, both now and in the future. He had disk drive issues also with his new / old “special” Kaypro.
B] We even discovered that in that area of the world, some made existing computers “look like” Kaypros, since Kaypros were so rare there. Tezza’s pictures show his is a very rare “real” Kaypro however, apparently!
27] My web site –
WWW.KAYPROSTS.ORG is very limited on Kaypros, since it also covers my decades of Science, Technology and Society [STS – hence the name KAYPRO + STS] research. But the pictures in the 2008 Calendar in the folder “ Special “ may help you find certain items on your Kaypro. The draft of my Kaypro book is also there, if you are interested in some of the history of that era. Two publishers are now reviewing it for possible publication. I gave a talk on it at the 2008 Trenton [NJ] Computer Festival and a copy of the draft is on their 2008 Festival CD.
28] A] My book documents some of the great confusion during those hectic years [Osborne’s “hypergrowth” term] concerning different models, versions, modifications, etc., both documented and undocumented, of computers like the Kaypro, made in a great rush to fill tremendous unprecedented demands at that time for such computers.
B] This is in addition to any of the many modifications that others may have made to these computers later, especially to try to keep them current with many rapidly new computer developments – e.g., the Kaypro “ 8 “ upgrades !
C] That is what can make it so difficult in “troubleshooting” issues. You may not be working with the Kaypro model / version / modification, etc. you think you are. So detailed specific information on any history and other aspects of the Kaypro you have can greatly assist in not wasting resources with respect to managing such issues. Pictures can be of tremendous help – e.g., Tezza’s Kaypro noted above.
29] A] Thus, we get into such long posts. I do fewer, but longer. You seem to have done some “homework” and seem committed, so I took the time to do this detailed response for you and others who have or will have similar issues.
B] Of course, when the issue is finally resolved, many times with the benefit of eventual “20 / 20 hindsight,” the resolution of the issue seems so obvious – how could we have missed it ? Again, welcome to “troubleshooting vintage computers !” But that is just part of the “fun” of it.
All the best and please let us know more detailed specifics about your Kaypro, especially any past history / pictures, etc., so we may be able to be of more assistance, besides reporting the results of “your adventures in troubleshooting Kaypros” for the benefit of all !
This all aids in the “knowledge base” we are all establishing on this and other sites for the preservation of actual “working” vintage computers for the future.
Frank
