EEVblog #955 - World's First Portable Computer Teardown

What's inside the world's first portable microcomputer?
The Osborne 1 from Osborne Computer Corporation torn down.
An Adam Osborne and Lee Felsenstein design.
ROM Dumps:
Field Service Manual:

Support the EEVblog through Patreon!

EEVblog Amazon Store (Dave gets a cut):

[fulkthered]

Looks like he saw a portable Singer sewing machine case and said "Let's put a computer in there".

[hughmulgrew]

The video board is an Australian add on to give 80 x 25 display on an external display using the composite video connector. It was installed here in Australia. It was accepted by Adam Osborne and here we honoured warranty with the changes made. Interestingly the Osborne 1 sold here in Australia for $1795 where most other importers of computer marked it up 200% - 300%.

[Jeffrey]

10:34 The "wasted space" is to protect the electronics board from impact damage. It will be lugged under an airline seat after all..

[leisergeist]

Groundbreaking indeed... if you dropped it, it'd break the ground alright

[mysticvirgo]

All the extra space in the cover / keyboard would make it a smuggler's dream :)

[coyote_den]

Your Osbourne 1 has an 80-column video upgrade installed. From the Wikipedia page:

The Osborne corporation offered a "Screen Pac" 80-column upgrade that could be switched between original 52 column and 80 column modes. Osborne 1 systems with the 80-column upgrade have an RCA jack installed on the front panel to allow users to connect an external composite video monitor. This modification was developed in Australia by Geoff Cohen and Stuart Ritchie and taken to the US by Stuart who turned up unannounced and sat outside Adam Osborne's office for two days. Osborne bought the mod as soon as they saw it and both of them worked with the Company to implement the mod. As a nod toward where it came from it was called the "Koala Project". Geoff went on to invent many other upgrades for Osborne's and was regarded as the Australian expert on the computers.

That explains the bodge wires. The daughterboard sits between the CPU and video connectors, but that still doesn't give it all the signals it needs so you have to tap various places on the logic board.

[evanjeffrey]

Wow! I had one of these as a kid. My mom used it in grad school, and then when she switched to a PC I got her O1. I used the external video! I think a lot of people used the external monitor. In the business school my mom studied in, it was common to have an external display in the office, but you could take the computer home if you needed to work on a paper or something.

[themaritimegirl]

The 50/60 markings on the spindle of the floppy drive don't indicate the rotational speed (it would have been a couple hundred RPM), but what set of markings to look at depending on if you were using a 50 or 60 Hz strobe light to calibrate the speed.

[larryholmes]

Dave, I was just beginning my first company when this came out. It WAS exciting for many people! I can't believe I rushed out and bought one as soon as they were available. I used it for a while to do all the things that needed doing back then for a new little company, that would have been called a "cottage industry startup ". It was a great time to be able to start a company with virtually no capital and just an idea of what to do with the thing to get it going. Well, I guess I ought to tell you what I know about some of the questions here.

One thing which seems to be on everyone's mind is: why is the case so BIG? Why is the keyboard case SO HUGE with SO much wasted space inside? Why is there so much wasted space here, there and everywhere? Well, the answer is very funny! It seems that osborne came across a warehouse full of empty cases for sewing machines at a bargain price, so they became the cases for the first run of the Osborne luggable computer! There is such an odd mechanical design and layout because all the pieces had to be put into the sewing machine case! The case was not designed for the computer, which would have made it much sleeker and streamlined. The computer had to be designed to fit into the case! Actually, I think that is quite clever. There was no standard or other designs to use as examples of how the design ought to look. It was just made so bulky because it was cheap and already made! Osborne did not have millions to spend designing the world's sexiest computer, and as you said, they did not know how many they would sell. Coming across all those empty cases they could just buy and insert a computer into fit their needs perfectly!

One thing that I read about Osborne, which I have never verified, was that Osborne didn't have a typical cost control system/authorization process for controlling how purchases were made and how costs were controlled. If you wanted a new exotic office desk and chair, like the guy down the hall got, you could simply buy one, and charge it to Osborne's account. I can imagine how such policies would bankrupt a new, small business very quickly.

I was very surprised when I read that Osborne was going under, after such a stellar startup! But, when I read v about the way they conducted their business, it was not hard to conclude that they could not survive. Thanks for presenting this tear-down!

[thomascott]

Hi, I enjoy your teardowns. I just wanted to point out one thing, when I was working on pc's, xt's, and at's we frequently had to adjust the speed of the floppy rotational speed by removing the drive from the drive case, and use the ever present fluorescent light as a 60 hz source and tweak a 10 turn trim pot. The drives were inclosed in a heavy cage that was gold anodised. If you were lucky you could sneak your jeweler's screwdriver in between the holes in the cage and save yourself the trouble of having to remove the drive and then reinsert after the adjustment. h what memories.

[frac]

That second sensor on the floppy is the write protect notch, not disk presence.

[ForViewingOnly]

25:28 Dave, I might be wrong but that sensor could be looking for the write-protect notch to see if it had a sticker covering it or not.

[doctorazizli]

first computer I worked with was Corvet (I think it was Russian made) in 1994. That was awesome time. you are interacting with the new technology and work/actually write programs in Basic language. you took me back to that time, Dave. 😊

[ossiebird]

Wow! I remember using one of these as a student in 1983 while being on work placement at the then Royal Aircraft Establishment Farnborough. I had joined a team of boffins who were working on helicopter gearing noise. To keep me busy and stop me from interfering with the real work, I was consigned to a very small room, the tea room as I remember and asked to write a basic fast Fourier transform simulation program with a high pass filter to identify the lower gear frequencies and exclude the higher pitch noise in the cabin. I don’t think they used my program. I do remember it creating an overwhelming amount of data.

[wolfgangschweiger]

In the late 80's, I learned CP/M on this incredible machine... long time a go and nice to see it again - thanx!

[WBaj]

I remember playing with my dads one of these. I was 8 in 81
I seem to remember it being quite yellow then.

[douro]

I almost picked one of these up once, when it was on the $1 table at the local computer surplus store. They had two of them, both in very good working order, and neither of them showed any yellowing of the case. I believe most of the people who had these used them for field diagnostic work, if they weren't using them as business computers.

[SuperAWaC]

i have one of these in my closet. still works. has all the fancy addons, and twice it's weight in software manuals with it. my grandfather used it when he designed satellites at ford aerospace/loral

[urbankoistinen]

The IBM 5100 was the first computer I got to spend serious time with. It is an earlier portable as was noted previously.

[John_Ridley]

At 25:30, that optical sensor is for write protect. There is no sensor for disk insertion.