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Another very early IBM 5150 restored

romanon

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Oct 1, 2013
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So finally I can introduce my next work, another very early IBM PC 5150, it was manufactured in late 1981, some components are made in early 1982. Inside of case is date december 18, 1981.
Serial number of tihs machine is 0128265

IMG_7896.jpg IMG_7889.jpgIMG_7887.jpg

Motherboard - 16-64kb with second version of BIOS from 10/19/81. Manufactured date 44/81 (some parts are from very early 1982)
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Very early IBM CGA with date 44/81 added by me
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Early IBM MDA card with date 08/82 added by me
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Very early IBM 64k memory expansion option card with date of IC's cca 40/81
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Early IBM floppy disk controller with date 07/82 added by me
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Floppy drive is standard Tandon TM-100-2A drive, its from 1982 year, without IBM logo on the front, added by me.

Power supply is standard early black 63,5W with red label from late 1981 / early 1982
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There is also original Disk Cover Plate from IBM

IMG_7891.jpg
 

SomeGuy

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Very nice! If I read that photo right, that FDC has the pre "A" Intel 8272 FDC controller that only does maximum 9 sectors (512 byte sized) per track. (Possibly the reason why DOS went from 8 to 9 sectors instead of 10)

And the early MDA card revision that one can hook to an RGB Multisync and mysteriously get high-resolution color text.
 

romanon

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Very nice! If I read that photo right, that FDC has the pre "A" Intel 8272 FDC controller that only does maximum 9 sectors (512 byte sized) per track. (Possibly the reason why DOS went from 8 to 9 sectors instead of 10)

Thanks.
Interesting fact! And yes, its Intel 8272.

SomeGuy said:
And the early MDA card revision that one can hook to an RGB Multisync and mysteriously get high-resolution color text.

Yes, this works fine on multisynch RGB monitor, I tried it some time ago :)
 

pgru2

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Sep 14, 2017
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What multisynch monitor it require? Would it work with non org. MDA cards that have similar looking pins on board?
 

romanon

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What multisynch monitor it require? Would it work with non org. MDA cards that have similar looking pins on board?

I am using TVM color monitor, it must be monitor for MDA/CGA/EGA modes. Works only with first revisions of MDA cards, with black sheet, or modified newer card.
 

ejs

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Oct 5, 2012
Messages
88
What is the latest date code off a motherboard chip?

Also, romanon, you have another Rev A 5150, serial 0306577, and it would be very interesting to learn the most recent date code from its motherboard as well. I'm keeping a list tracking all the early 5150 serial numbers because I'm trying to see if there's a coding scheme or if it's simply sequential. So far it's all been sequential but with one exception that I haven't been able to verify.
 

romanon

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What is the latest date code off a motherboard chip?

Also, romanon, you have another Rev A 5150, serial 0306577, and it would be very interesting to learn the most recent date code from its motherboard as well. I'm keeping a list tracking all the early 5150 serial numbers because I'm trying to see if there's a coding scheme or if it's simply sequential. So far it's all been sequential but with one exception that I haven't been able to verify.

Lates date code is 8203.
Computer number 0306577 is the past, it was mostly composed from various parts added by me, so finding some logic in dates is totally irrelevant. Most part was from early 1983 year. This computer was decomposed for parts.
But I have another early PC with number 0132291. All dates and information about components is based on my web page https://ibm-pc.webnode.sk
I am also interested in early serial numbers. As I found, in 1981 was manufactured only computers with number less than cca 0125000. My computer has date december 18, 1981, but some parts are from early 1982. Also its interesting why they started counting from 0100000, not from zero. I dont see any logic. I have IBM PC XT with S/N 00027853 so XT was counted from zero.
 

ejs

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Oct 5, 2012
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I am also interested in early serial numbers. As I found, in 1981 was manufactured only computers with number less than cca 0125000. My computer has date december 18, 1981, but some parts are from early 1982. Also its interesting why they started counting from 0100000, not from zero. I dont see any logic. I have IBM PC XT with S/N 00027853 so XT was counted from zero.

0125000 sounds about right, I've found a photo of machine, 0126083, with a RAM chip date code of the 43rd week of 1981. They continued with the serial numbers and cut over to rev B before 320852 and sometime after 0290143.

Oh yeah and the first rev B machines seem to just follow in the linear serial number sequence. They didn't switch the serial number scheme until later.
 

chris_nh

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Jan 28, 2019
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New Hampshire
Nice pics romanon, that is a nice looking machine.

ejs:codes

I have 2 early 5150s and I checked the numbers for your list. Also interesting, I scanned the serial number barcode and it reveals some extra interesting bits, note the extra letter after the serial number.

Machine #1) SN# 230980, Barcode: 023.980M, date code 8233 (latest I could find, RAM chips)

Machine #2) SN# 277286, Barcode: 0277286W, date code 8240 (on board)
This one also has a silver power supply, but I believe it is original because it has an early type fan
 

romanon

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Oct 1, 2013
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Slovakia
Yes, there is also some letter after scanning bar code. I have 0128265O and 0132921I, but I dont know about any meaning.
Also noticed, that very early 1981 motherboard has different color of power supply connectors, unfortunately not my cause.
5150A-1981MB.jpg
I am very interesting in counting from 0100000 instead of zero. Someone with any information or suggestion?
 
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