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Floppy drive update!!!

GottaLottaStuff said:
Here's a somewhat reasonable one, if you can win it:
http://cgi.ebay.com/Original-IBM-5-...C_Drives_Storage_Internal&hash=item43a8105082

I was being serious before, if you need to borrow a motherboard I'll send it out Tuesday. :)
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Yeah, I saw that one. I have it in my watch list. He also has a nice AST sixpack plus for a good price. The problem is that my wife and I both work and I can't try the last second thing. I really want both. Oh well...If the timing were a bit different, I would jump on it. Now if he had a buy it now option...
 
GottaLottaStuff said:
"... 360 Kb drives are just so expensive. "
Ten years ago I scrapped about 50 full height 5 1/4" disk drives. It's all my fault. :(
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Not just your fault. 10-15 years ago you couldn't GIVE full-height 360K drives away, and about the only reason you could give half-height 360K drives away was because you could use them to fill an empty drive bay when you'd lost the cover. So everyone was discarding them. I discarded a few myself.
 
Some of us had lots of storage space and saved boxes full of 5.25" FH FDs, both 180K SSSD and 360K DSDD. Now it's just a matter of going through them and repair/align/test them. Even have boxes of 720K 3.5" drives :) It's paying off now.
 
Druid6900 said:
Some of us had lots of storage space and saved boxes full of 5.25" FH FDs, both 180K SSSD and 360K DSDD. Now it's just a matter of going through them and repair/align/test them. Even have boxes of 720K 3.5" drives :) It's paying off now.
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Druid:

Nice call, saving all those drives. I have made plans to try for this one on E-Bay, (link below)but if that fails, would you be willing to part with one of your working drives? If so, how much would you want for one?

http://cgi.ebay.com/Original-IBM-5-...&otn=4&po=LVI&ps=63&clkid=1108389083946869382
 
MikeS said:
Careful! He does say that this is a TM100-4 80track drive which is NOT compatible with PC/XTs despite what he says; the PC used TM100-2 drives.
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Good catch, 80 = 720, just ran across that ad and it said 5150....but I did say "might be"
Looks like a bit of lying going on there? On ebay no less, what is the world coming to!
 
bettablue said:
Druid:

Nice call, saving all those drives. I have made plans to try for this one on E-Bay, (link below)but if that fails, would you be willing to part with one of your working drives? If so, how much would you want for one?
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You'd have to ask MikeS about that. The only TM-100-2s I have are his and they are here because they don't work (yet).
 
RJBJR said:
Good catch, 80 = 720, just ran across that ad and it said 5150....but I did say "might be"
Looks like a bit of lying going on there? On ebay no less, what is the world coming to!
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Could be an honest mistake; not many folks know what model PC/XTs used, and they do look right.
 
On the TM100-4's, you can usually flip the door latch up and look at the sticker underneath. -4s as they came from the factory said "96 TPI" quite clearly. -4Ms said "100 TPI". Admittedly, it's possible to fake things by exchanging the faceplate assembly with that of another drive.

If you're not stuck on the idea of a full-height 5¼" drive, half-height 360K drives might be easier to find. Indeed, many 5150 owners who installed 5¼" hard drives went to half-height floppies to keep the two-floppy capability. IBM did offer the half-height drive as an option under the moniker "IBM Slimline Drive".
 
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Well, I missed the drive with controller on E-bay by 50 cents! Oh well. I have a friend who might have one here in Vegas. It is the correct 360 Kb drive too. If he does still have it, he's giving it to me in trade for some work I did for him a while back. The memory is another issue. I'm wondering something though. Yes, I do believe there is also a persistant memory error in my 5150. So where do I begin? If I pull the memory card out I know I need to make sure the dip switches need to be set properly. I'm confused though. (Nothing new there, huh?) There are two banks of dip switches. Which ones do I need to set? If the problem is in one of the onboard chips, how do I determine which one it is?
 
Here is some info in PDF files. The bigger one is the first 9 chapters of the Personal Computer Family Service Information Manual, chapter 4 will tell you everything you need to know about the 5150 with all the jumper settings at the end of the chapter. The smaller one is the IBM PC/XT summary which is an accordian folded pamphlet that has some good error code info and other useful troubleshooting info.

http://home.earthlink.net/~russellbaker/Pcsim1-9.pdf

http://home.earthlink.net/~russellbaker/PCXTSmry.pdf

When looking at the switch settings for the motherboard make sure you are in the right section as there is one for 16-64k boards and one for 64-256k boards. Page 4-32 starts the 64-256k memory switch settings, the whole of chapter 4 should be an enjoyable read. Have fun!
 
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Dip switch settings are in the back of the Guide to Operations. You do have one of those, right? :) Oddly, the settings are different between the 16-64K board and the 64-256K board. For the 64-256K board 256K total memory would be
switch block 1 3 &4 OFF
switch block 2 1 ON 2,3 OFF 4, 5 ON 6,7,8 OFF

On switch block 1 8 is always ON
On switch block 2 6,7,8 are always OFF.
That's how you tell which one is which. :)

25 year old dip switches can be a pain. You may have to switch them several times or drip contact cleaner into them.
They were like that 20 years ago.

The problem could be that the motherboard slot or card edge on the memory card needs cleaning. If pulling the memory card fixes the problem, don't throw the card away!

To find a bad chip, you'll need IC pullers. (at least) They look like big tweezers and hook under the ends of the chip. One row is soldered down, the rest is in sockets. Take out the socketed ram one row at a time, set the dip switches, and see if the error goes away. Put it back in a different row and see if the error moves around. (You'll need DOS and a memory checker program for that) If you get down to the one row of soldered ram and it still doesn't work, you unsolder it, put in sockets, and swap in different chips. Or buy a new board. If the memory card has socketed ram of the same type (4164 ?) You can swap a row from the card to the motherboard. It is very easy to bend the pins with all that swapping in and out. Usually the IC pullers come in a kit with pin straighteners and such.

I don't have a scanner set up at the moment, but if you can't find the Guide to Operations posted somewhere, I can take pictures of the dip switch setting section of mine.
 
GottaLottaStuff said:
To find a bad chip, you'll need IC pullers. (at least) They look like big tweezers and hook under the ends of the chip.
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No, you don't need them. I find those stupid things usually make things worse. Invariably one side of the chip pops out first and you bend the pins all to hell. Just use a little flat blade screwdriver and lever the chips up. That's what I've always done. The chip puller is great for pulling keytops off keyboards though...

The DRAM chips used by the PC are very, very, very common and cheap. I actually have a DRAM tester, but even then, I usually just swap a row of chips at a time until I find the bad bank, then you can go one by one and find exactly which chip in the bank is bad. It's usually faster to change them around in the computer than it is to go get the tester.

But yeah, set the board up to just use the onboard memory, without the expansion card, and see how that works. If it's still showing errors, swap a bank of chips at a time until you find the bad one.

-Ian
 
Several things are happeing all at once. I have a donor 5150 being delivereed this week. Supposedly everythin is good on the computer with the exception of the mother board. It has one double height floppy drive, a 394kb memory board, and a set of parallel and serial ports. So, I am going to take things VERY slowly and start by replaceing the generic memory card in my 5150 and work outward from there. Then I'll add in one card at a time, setting the interups accordingly to add the serial ports. The donor also has a network adapter, but I don't see this as being anywhere usefull to me. There is a coax connector that won't interface with anything I have. And since the video controller is a mono, I won't be using that either.

The 2nd major thing is that I also bought a 5160 computer for the wife to play some vintage DOS games on. This one is guarantted to work. I'm purchasing it from a very well known member of VDF so I trust the computer will be fully functional. It's coming with DOS 3.3 installed on the hard drive and also has a 5 1/4" double height floppy drive. It is coming with mono graphics card, parallel and serial ports and at least a 20 meg hard rdrive.

So, when the donor computer arrives, I'll be busy for a few days. Hopefully, I'll be able to get it rinning the way it is supposed to be running. Wish me luck. Maybe after I'm done I'll put it together too with a new mother board and drives. We'll see. I wonder though, if I rebuild it as a terminal connected to my main 5150, or even the XT, how that would work.
 
New update - 7/23/2011

Sorry to revive an old thread, but I do have some good news and an update on my 5150.

I have to say, you all have been fantastic! Putting up with my rambling and frustration and still offering to help. Not too many people would have botherd. And, to find someone locally; Matt, who I work with at UPS, who also does this kind of repair work is amazing! (I have been very lucky in the friend department.) Matt's also co-owns and works part time at a computer repair shop here in Las Vegas. They have been working on machnines like this for over 25 years. Too bad they don't have access to some of the parts for these old IBM's. Still, Matt is a great guy to have as a friend.

Matt offered to help me with getting my 5150 working, so he checked out the motherboard's memory and the memory on the expansion card. He determined that the majority of the issues I am experiencing with this machine is due to the floppy drives. Both drives are seriously out of alignment and will not read a complete diskette. In one of the drives, the heads do not completely run the full range of motion, even after a complete lube job. The other has some other component issues as well. Both drives need to be replaced. So, I have a donor 5150 system arriving on Monday with a known good Tandon drive. Unfortunately, it the computer is missing the 2nd drive alltogether and there is no cover plate where the other drive was mounted. We think the previous owner was attempting to install a 5160 power supply and blew the motherboard, but luckily, the floppy drive is still in good shape and it tested out perfectly. (Maybe when I get my 5150 working properly, I'll use the case to rebuild an expansion unit.)

Does anyone know where I can get another good working full height Tandon 360 Kb floppy drive I can use as a replacement for my 5150 for around $100.00 or so? Maybe someone here has one for sale? I'll even pay extra for expidited shipping if necessary. Once I have the 2nd drive, I will replace both of them at one time and Matt will do a complete system test on the rest of machine. That way he can eliminate and repair any more persistant memory issues that may still exist. Unfortunately, we can't really test the computer properly until we get a good drive installed to run a full series of diagnostic routines. If it turns out that there is still an issue with the memory board, we will be replacing that too. Matt already has a line on a nice 384 Kb sixpackplus just in case.

Hopefully, with a little luck, someone out here in the forums will have a good, working, replacement drive I can purchase. Thanks again for all your help and advice.
 
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