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Unable to use MFM drive in a 5150??

Ok, so there are no matching serial numbers, and you didn't have to use a torch to get the motherboard out. I think you are missing the entire point.

Your right.. I missed the entire point, thats why I AM putting it back together, and selling it as a whole. I already told you I am putting it back together, yet you still criticize...

You broke apart a working system to part it out. A very old and relatively uncommon working system. In my eyes and in the context of vintage computing, that is sin. Especially since it isn't a lot of money in the grand scheme of things, and you had other options.

Your making an awful lot of assumptions to base your attacks on. I never even said this was ever in the original case as a complete and working system... Mind you, I do have the original case, but you still based your attacks on assumptions.
When I got this system, it was completely dead, and non-working.. full of mouse shit, and dust half an inch thick. I saved it from the dump, replaced a cap in the power supply, reseated the ROM chips, and fixed cold solder joints on the keyboard jack. and it NOW it works.. If just about anybody else came across this, it'd be long gone.

Any time you remove a motherboard or components from a case you bend them, possibly stressing them. Did you bother to wear a static strap as you tore the machine apart? (I'm betting not, but it's not like we can prove that one way or another.)

I've been working on machines for 20+years now. Im not a gorilla, I didnt bend the board, and even if it flexed slightly, PCB's are designed to take a small amount of that. I didnt wear an anti static strap. Never have, Never will. The machine stays plugged in for a active ground, and I touch the case to discharge ESD before working on any board. This is more than sufficient unless I have a tesla coil running in the same room. I am confident I can pull the board out and remount it 400 times , and it will still work as good as new.

You've got three bids on that motherboard on eBay now. What are you doing to do, cancel the auction and say you lost the motherboard?
Yes.. I am going to do that. I cancelled the auction and said it is no longer for sale. You CAN do that on ebay you know...

Did it occur to you to offer it to people here first? People who are actually interested in preserving vintage computers?

By posting it on ebay, and then posting the link here, I AM allowing EVERYBODY here the opportunity to bid on the item. I no longer sell outside of ebay, due to being screwed in the past. You want it? BID ON IT.
 
You are upset at the criticism, and that's understandable, but, you have to realize that the people here are passionate about Vintage computers and their preservation.

We see enough machines get chopped up needlessly for the sake of a few bucks more.

Some of us came here, like you, to get some information on a Vintage machine, to sell it, most likely, and soon discovered that we were chopping up pieces of history.

IF you hang around here long enough, you will come to understand that any machine, if possible, should be restored, and, if sold, sold as a working entity so that someone, somewhere, might enjoy the pleasure of that era's technology.

Butchering it, around here, is about the same as being a horse thief a 150 years ago and, if possible, would carry the same penalty :)

Try and understand the reaction.

Druid
 
I'm glad you saved it from the dump and got it working. But after a labor of love like that, I find it kind of of strange that you were willing to ditch it so quickly.

2nd, I have a very low regard for people who decide to sell on eBay and then cancel the auction. You are cancelling for the right reason, but you've just annoyed three people who have probably been looking for a board like that for a long time.

You can do what you want .. like I said before, it's your property. Have fun.
 
Alright folks.. its back together and booting.. Here are some pics. Offers are welcome, however I will probably be putting it on ebay later this eve:





 
Theres an early 5150 on eBay at the moment, although not advertised as such:
http://search.ebay.com/120147740636
My query to the seller seeking the BIOS revision resulted in, "Sorry...the boxes are sealed & ready to ship." Thus any buyer will be taking a big risk if they're buying to get an early BIOS.

Note that from my experience, just because a machine has no 'circled B', AND has no cards with an expansion ROM BIOS, you can't imply that it has an early BIOS. I know that where I worked in the 80's, we would have fitted new BIOS chips during any maintenance on a 5150.
 
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I'm surprised no one has told the original poster that there is a BIOS chip upgrade that IBM made to upgrade the 16-64k motherboards to the BIOS on the 64-256k boards. If he replaces the BIOS chip, it will have the BIOS functionality of the 64-256k boards including hard drive booting.

I saw one offered on Ebay just a week or two ago, in the "Buy It Now" section. It was listed with the original IBM part #. I think it was only about $15 or so.
I've just been through my chip collection. I have 12 of these third revision BIOS chips. They should be of use to forum members who have a dud 5150 motherboard and want to eliminate the BIOS chip as the cause. That's of course if they don't have another 5150 motherboard to swap the chip from.
 
Note that from my experience, just because a machine has no 'circled B', AND has no cards with an expansion ROM BIOS, you can't imply that it has an early BIOS. I know that where I worked in the 80's, we would have fitted new BIOS chips during any maintenance on a 5150.

I've noticed that neither of my two 64-256 5150's have the circled B on the case. In fact, I've never seen a circled B on a UK-assembled 5150. Maybe it was a USA thing?

Mine are marked as "Assembled in Greenock, Scotland".
 
From the first edition of Upgrading & Repairing PC's:

Only IBM Personal Computer models 1, 13, 14, 64 and 74 require updating of BIOS. These units were all sold before March 1983. Any computers sold after March 1983 had the ROM mentioned. Models that have had an Expansion Unit Model 1 attached don't need further updating because the new BIOS was included with this option. Later models (including 104, 114, 164, 166, 174 and 176) were built with the new functions included in their respective BIOS. The serial numbers of PCs originally manufacturered with the early BIOS modules have a serial number of 0300960 or lower. PCs with the newest ROM have the letter "B" inside of a circle stamped on the back of the system chassis in white ink.

In another area of the book, the 5150 motherboards are described:

Type 1 - Used 16K RAM chips in four banks for a total of 64K. Had Version 1 or 2 of the ROM BIOS, which is now obsolete.
Type 2 - Used 64K RAM chips in four banks for a total of 256K. Had Version 10/27/82 of the ROM BIOS, which was the last version offered.


Combining parts of those two blocks of information, one arrives at: all type 2 motherboards (64-256K) have the letter "B" ...

I've heard that those Scots are cheap. Maybe they saved money by not hiring someone to stamp on the "B".
 
redruM69,

I am formally apologizing - I was way over the line in my previous posts. The only defense that I can offer is that I've seen very many people part out machines with $$$ in their eyes, and nothing more. Your posts sounded like you were one of those.

Yes, I need to chill out ...

Mike
 
I've heard that those Scots are cheap. Maybe they saved money by not hiring someone to stamp on the "B".

You know, you are probably right :p

The 5150 was never officially sold here until 1983, so an 'early' system would have been either a grey import or special order. I've only seen one early system over here, which was non-working.
 
Although IBM had been making equipment in Australia since at least the mid 70's, it didn't shift to personal computers here until the 5160.
Consequently, all 5150's over here are imports. Every one I've seen is US made.
 
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