Found a totally mint rev A 5150!

[ejs]

So I got *incredibly* lucky on Saturday and picked up this beautiful early 5150 for a very good price.

Notice the lack of the "B" stamp on the back, along with the black fan grille:

Inside you can see the entire power supply is painted black. (This pic was taken after I replaced the clone Hercules card with an original rev A MDA card for authenticity's sake)

Naturally it has the 16KB-64KB motherboard.

The BIOS chip is the 2nd revision (5700671, aka 10/19/81)

It's also got an 8088 with the interrupt bug:

And it came with an IBM DOS 1.10 boot disk in the drive!

The power switch also looks different and is missing the 'I' 'O' icons.

To get it to boot, I had to replace two 4116 memory chips and reseat a socketed PAL on the (3rd party) memory expansion card. But look at that, DOS 1.1!

I just can't get over how clean this thing is! The previous owner must have used it a couple of times then packed it away in climate controlled storage.

 

[LiqMatrix]

Wow! Just beautiful. Amazing you can still find an almost 40 year old system like this in that condition. Great catch!

 

[paul]

Nice find!

 

[RadRacer203]

Nice find! Mine had a stamp underneath the cover that dates it to August of 1981, does yours have that stamp?

 

[alank2]

Beautiful condition! Good for you! Is that display yellow or amber? Looks fantastic.

 

[bobba84]

Awesome!!!

 

[ejs]

Nice find! Mine had a stamp underneath the cover that dates it to August of 1981, does yours have that stamp?

Haven't seen a stamp. Hmm.

 

[ejs]

Beautiful condition! Good for you! Is that display yellow or amber? Looks fantastic.

Amber, it's a clone monitor, not original IBM.

 

[modem7]

Haven't seen a stamp. Hmm.

IBM possibly sourced some 5150 parts from various makers, and for those parts, may have had multiple lines of supply. So, imagine that company A and company B make the cases. It could be that only company A put a date stamp on their cases.

Even if you find a date somewhere (e.g. cloth attached to speaker assembly) on a part, that date possibly only applies to the part. I have seen nothing from IBM that informs resellers or buyers on how to determine the assembly date of a 5150. It is possible that IBM may have internal documentation that lists 5150 serial numbers and their corresponding assembly date.

 

[ejs]

Today I also noticed that the keyboard plug is different. See below photo. The plug on the right is a late-model PC/XT keyboard with the molded IBM logo plug. The left plug is from the rev A 5150 keyboard. It may look like a replacement plug however the cables are the same length. I'd expect a replacement to have a shortened cable.

 

[ejs]

Forgot to mention that the latest IC date code I found was the 35th week of 1982. One of the floppy drives also has a stamp that reads "3782" which I am guessing refers to the 37th week of 1982. So I'd estimate the date of manufacture to be September 1982. This lines up with the BIOS chip. Any later and it would likely have used the 10/27/82 BIOS.