5150 Serial Numbers

[Andrettigto]

I'm interested in learning how the serial numbering worked during the PC's production life.

Did they start with zero or like cars, use only part of the number for sequence? When the XT came out, did IBM just keep increasing the number or start at zero again? At EBay auctions, when a seller lists a number, how do you gauge "where" it is in terms of the calender years?

I've searched the forums here but could not find anything on this topic. There's probably something on the web but I can't seem to find anything either.

Maybe some fellow owners who are interested could give some input on what sort of data would be worth collecting.

Possible things to list:
- model PC or XT
- motherboard type (64k or 256k)
- serial number
- purchase date (if even known)
- capacitors on ends of memory banks? (I read that some didn't have them?)
- Cassette port? Was it always on the PC only? Relay, same thing?
- power supply color (or were they all black?)
- Drive cage design? When did they modify it to hold half heights?
- Dip switches always blue?

O.K. so here's my system:

PC 64k
0238960, around Oct.'81
caps beside dimms and at board edge
cassette and relay
black p/s (upgraded now)
Full height mount only (fabricated brackets to hold half height 225's)
Baby blue switch box

So please share what you have and tell me where I'm wrong here.
Carlos

 

[modem7]

I'm interested in learning how the serial numbering worked during the PC's production life. Did they start with zero or like cars, use only part of the number for sequence? When the XT came out, did IBM just keep increasing the number or start at zero again?

If someone knew, I figure you'd have an answer by now.

At EBay auctions, when a seller lists a number, how do you gauge "where" it is in terms of the calender years?

Even if one did have access to a serial-number-to-date cross reference, no matter where you see a PC/XT/AT, the only sure thing the serial number would reveal is the date of manufacture of the case. That's because any of the case components (PSU, motherboard, etc.) may have been upgraded, or even downgraded.

So if your question then becomes, "Is there then documentation that from a serial number will inform me as to what was fitted to that serial number?", my answer is, "For the IBM PC family, I and other forum members are looking for the same information." So for example, if your early PC (s/n 0238960) has double sided drives, was the PC supplied like that, or were single sided drives supplied?

I've searched the forums here but could not find anything on this topic. There's probably something on the web but I can't seem to find anything either.

If you are writing about PC family serial numbers, I don't think you'll find anything (because I'm sure myself and others would have found it by now).
As for models, release dates, configuration, etc., the information is in books and on the web. Some example web sites:
http://mastodonpc.tripod.com/ibm/type.html
http://maben.homeip.net/static/S100/IBM/books/Original PC Hardware Reference.pdf
http://www.selectric.org/old5150/index.html

- capacitors on ends of memory banks? (I read that some didn't have them?)

Re PCs (IBM 5150).
Early PC motherboards were 16-64K types, later were 64-256K types.
The RAM in the 16-64K types is 4116, which requires +12V/+5V/-5V
The RAM in the 64-256K types only requires +5V. As a result, the 64-256K type doesn't have +12V/-5V caps in the RAM area.
So at a distance, one way to distinguish a 16-64K from a 64-256K type is to look at the caps to the left of the parity RAM chips - the 16-64K type has two caps next to each parity chip, the 64-256K type has one.
Maybe that's what your "capacitors on ends of memory banks" was about.

- Cassette port? Was it always on the PC only? Relay, same thing?

Yes, and yes. The relay is part of the cassette port circuitry.

- power supply color (or were they all black?)

Only the 'early' PCs had black power supplies.

 

[per]

Did they start with zero or like cars, use only part of the number for sequence?

In the start, yes, but at some point between 1983 and 1985, they changed the form of the number so that it contained more information than just a serial number (If I am rigth, they did at least change it's appearance).

When the XT came out, did IBM just keep increasing the number or start at zero again? At EBay auctions, when a seller lists a number, how do you gauge "where" it is in terms of the calender years?

Since I got an XT from 1983 labeled "S/N_0010472", and you refer to a PC from ~1981 numbered "0238960"; I assume the numbers were reset for the XTs.

PC 64k
0238960, around Oct.'81
caps beside dimms and at board edge
cassette and relay
black p/s (upgraded now)
Full height mount only (fabricated brackets to hold half height 225's)
Baby blue switch box

So please share what you have and tell me where I'm wrong here.
Carlos

Note that the date in the BIOS doesn't nesecarely mean the date the machine was sold. Look for a stamp on the inside of the chassis for the assembly date, and you may look for date-codes on the IC's if no stamp is present to get an idea about how old it is.

Also note that it is problably worth more with the black PSU. They only shipped them in the early PCs, and replacing it may ruin some of it's "originality".

All PCs and XTs were shipped with FH mount only. Some of the later XT models did, however, sell with the fabricated brackets you are talking about.

The colour of the switch block doesn't really mean anything.

 

[Andrettigto]

As for models, release dates, configuration, etc., the information is in books and on the web. Some example web sites:
http://mastodonpc.tripod.com/ibm/type.html
http://maben.homeip.net/static/S100/IBM/books/Original PC Hardware Reference.pdf
http://www.selectric.org/old5150/index.html

Thanks for the links, there's some really good stuff in there to spend some time with. Any others you want to share?

Re PCs (IBM 5150).
Early PC motherboards were 16-64K types, later were 64-256K types.
The RAM in the 16-64K types is 4116, which requires +12V/+5V/-5V
The RAM in the 64-256K types only requires +5V. As a result, the 64-256K type doesn't have +12V/-5V caps in the RAM area.

I never knew that about the earlier memories voltage difference.

Yes, and yes. The relay is part of the cassette port circuitry.

I wasn't thinking very clear when I wrote that one, Cassette motor control!

Only the 'early' PCs had black power supplies.

Problem was the 65w supply was a common "upgrade" back then. It couldn't even handle one FDD + HD. I do remember pulling out the cooler fan and learning it required A/C voltage.

-------------------------
"If someone knew, I figure you'd have an answer by now."
If they were sequential from zero, IBM was sure pumping out the units back then. For my system that would equate to roughly 20,000 units a week if production started in August.

 

[Andrettigto]

Since I got an XT from 1983 labeled "S/N_0010472", and you refer to a PC from ~1981 numbered "0238960"; I assume the numbers were reset for the XTs.

After you wrote this, I looked up some for sale and saw the same trend. You have a very early XT, nice.
http://cgi.ebay.com/Rare-Vintage-IB...2?hash=item35a27e892e&_trksid=p3286.m20.l1116

...the date in the BIOS doesn't nesecarely mean the date the machine was sold....

The October date I was giving was the date I purchased the system new. I think there was 3 different BIOS versions released in total?

The colour of the switch block doesn't really mean anything.

I was just curious in learning about other 5150-60 models. A little thing like the DIP switch could show a change in suppliers like when the early Tandon drives started coming out with the IBM logo on them. Production changes during the models life.

I guess I'll stick to looking at pictures.

 

[modem7]

Thanks for the links, there's some really good stuff in there to spend some time with. Any others you want to share?

Those are ones I wrote down. But just now searching again for something I used recently, reveals something which includes prices: http://cd.textfiles.com/rbbsv3n1/pc_s/partpric.doc

The October date I was giving was the date I purchased the system new. I think there was 3 different BIOS versions released in total?

Yes. See http://www.vintage-computer.com/vcforum/showthread.php?t=9692

I was just curious in learning about other 5150-60 models. A little thing like the DIP switch could show a change in suppliers like when the early Tandon drives started coming out with the IBM logo on them. Production changes during the models life.

Discussions like that have happened in these forums. The 'IBM logo on Tandon drives' was discussed in the past year, and I remember a discussion about the colour of motherboards.

 

[Andrettigto]

...searching again for something I used recently, reveals something which includes prices: http://cd.textfiles.com/rbbsv3n1/pc_s/partpric.doc

modem7, that's a neat listing and it got me thinking. Back then, I was fanatical about saving everything. Without getting into details, about 10 years ago when I moved I lost most of the computer documents I was collecting. :O It was about 25 boxes of books, magazines, all my packaged/boxed software, binders with EVERY PC advertisement (even before the Charlie campaign), my original BIOS, PSU, the list goes on and on.

ANYWAY... back to this list you linked. I remember the ComputerLand price lists that I also collected. And yes, another binder MIA. But some lists I picked up were duplicates and never went to the collection. After reading your link, I remembered about a year ago finding six price sheets mixed in with my car stuff. So I've just come in from my garage and took pictures of the oldest two, dated Sept. '82. This is in Canadian dollars, but it looks like I was getting U.S. prices to compare the exchange. The highlighter bleed thru is from other price sheets.

Discussions like that have happened in these forums. The 'IBM logo on Tandon drives' was discussed in the past year, and I remember a discussion about the colour of motherboards.

I've found that thread, good reading. I'm getting better at using the search

 

[nathan]

How about some enterprising individual starting up an IBM PC Registry? Owners 5150s/5160s/et cetera could enter their machines' serial numbers, revisions, dates, et cetera. Such an effort could do a decent job in pinning down the sort of info that the OP is looking for. To be honest, I almost posted his same question about a month ago, so I would probably volunteer to code up such a site (and host it) if we can come to a consensus as to what info we'd like in the registry.

 

[barythrin]

That's an interesting idea. Depending on how many people you get to sign up. I'm not sure if this http://www.old-computers.com/club/collectors/default.asp could be a similar source and it's just the one I know of (there could be and surely are lots of other sites) that could also add that sort of information to their listings.

It'd be somewhat interesting to see serial numbers, etc added but allow folks to sign up and put up their collection of gear and whatever details they'd like to provide. I like this sites settings as it has status like working/nonworking/repaired and if it's for sale/trade or not.

You know, that's what someone should do. I don't know how without just eating the costs and not having those horrible pop-up crazy ads but someone should host a site that lets collectors have their own webpage. A geocities for computer collectors. Then you could have everyone's collection listed, a free page for folks to put what they want or about themselves, etc. Well ok that probably just bloomed into a million dollar expense so carry-on ;-)

- John

 

[per]

I've found that thread, good reading. I'm getting better at using the search

Note the prices on the operating systems. If you just bougth a multi-thousand-dollar PC and was to pick only one of the operating systems listed on the picture at the given prices, what would you have picked? (I know, it's obivous that most normal people hasn't heard about anything but one of the choices.)

 

[linuxlove]

Didn't the 5150 have the option of PC-DOS, CP/M-86 or the USCD Pascal system? I read that it did in Bill Gates' book, The road ahead.

 

[Andrettigto]

Note the prices on the operating systems. If you just bougth a multi-thousand-dollar PC and was to pick only one of the operating systems listed on the picture at the given prices, what would you have picked?

CP/M 86 was doomed from the beginning because of the price structure. We've all read the stories of Gary Kildall flying around in his plane while he made the IBM's wait for him. It looked like IBM was holding a grudge after they left.

 

[Andrettigto]

Didn't the 5150 have the option of PC-DOS, CP/M-86 or the USCD Pascal system

It's on page two of the price sheet.

 

[Marrr]

Didn't the 5150 have the option of PC-DOS, CP/M-86 or the USCD Pascal system?

There was also PC/IX, but it required a HDD, so I guess this option was added sometime later.