Naked at 30: Osborne 1 stripped to its chips
He ain't heavy. He's my TV typewriter
Photos The Osborne 1 – the first mass-market portable computer – turns 30 years old this month. And what better way to celebrate than by tearing one apart?
One problem: I couldn't get my hands on an original Osborne 1. But I was able to tear into the next best thing: the slightly remodeled follow-on to the original, also known as the Orborne 1, but sporting a different case.
Created in 1981, when seeing "Made in U.S.A." on a logic board wasn't surprising (click to enlarge)
The original Osborne 1 was a tan-and-black affair with its keyboard latches on the sides and its keyboard connected to the main body with a ribbon cable. The follow-on was a light gray-and-blue unit with keyboard latches on the top and the keyboard hooked up by means of a coil cord.
There were a few other physical changes as well. But the guts of the two models were essentially identical.
You could choose to either detach the keyboard (shown) or use it to prop up the case (click to enlarge)
When lugging the beast the few blocks from The Reg's downtown San Francisco office to my car for its trip to my photo studio, I gained a new respect for the computing pioneers who had to lug this hefty beast on their daily commute: its too-small handle dug into my hand – well, both hands, actually, as I had to shift it from hand to hand as my arms grew tired.
Thirty years of progress: the Osborne 1, 1989's Macintosh Portable, and an 11.6-inch MacBook Air (click to enlarge)
The manufacturer's name graces the bottom of the Osborne 1's case (click to enlarge)
Compare, if you will, the Osborne 1's 24.5 pounds with the 11-inch MacBook Air's 2.3 pounds. Also note that the Air's display provides about four times the screen real estate than does the Osborne 1's five-inch CRT. Finally, remember that the big fellow cost $1,795 when new - that'd be $4,349 (£2,669) today. The MacBook Air lists for $999.
A slide-open vent enables convection cooling for the fanless Osborne 1 (click to enlarge)
There is one thing that the Osborne 1 and the MacBook Air do have in common, however: the lack of a cooling fan. But then again, a 4MHz Z80 running at about one watt of power didn't exactly turn the capacious innards of the Osborne 1 into an Easy-Bake oven.
Speaking of capacious innards, let's open up the Osborne 1 and take a look inside.
Next page: Tiny CRT, enormous floppies
COMMENTS
caps
I made that mistake twice myself but it was on the same day. I was examining a power supply with a really big al-elec 200V cap. It discharged on me. After I picked myself up I made the stupid assumption that now that it had kicked my ass it must be fully discharged. It wasn't.
The really amazing fact was....
...that the OS fitted on a single density 5.25 inch disk! What happened? Oh ya M$ happened, now you need >1Tb disk just to get started.
Fond memories
Owned the Rev A myself. And did have the external monitor as well as the 300 baud Osborne pulse dialing modem that fit into the floppy holder slot by the port. The Rev A had double density single sided drives where the original had single density. So everyone cut the notch in their floppies so we could turn them over and use the backside. My Osborne I ran: Turbo Pascal, COBOL, LISP, C, Z80 Macro Assembler in addition to the normal package and the plethora of add ons through the many BBS CP/M sites. At school, armed with a 300 baud modem, I did my mainframe work via Wordstar and uploaded it to save valuable "dollar" allotments on the school's mainframe. I was the envy of my dorm since 128 scrollable display is good enough to display the majority of mainframe output which was formatted for a maximum 132 character line printer. I made my own modifications to OSWYLBUR to handle the strange Osborne I modem... and many of us replace the CP/M shell with ZCPR, a command replacement with more features. I even hacked in a pulse dialing modem routine in place of the built in DIR command, since most people used a directory listing program from disk instead. I also programmed a game using the Software Toolworks C compiler where you flew around the screen and turned asterisks into boxes. The asterisks would kill you if you ran into them and the boxes were like walls, so as you played your ability to move about the screen decreased. What fun! I also wrote a mainframe 370 assembler in macro Z80 assembler. This allowed me to do a lot of my labs without using valuable compute time... just had to upload the final product. In high school, I developed a text adventure game (ala Infocom) where you had to solve chemistry problems to get through obstacles. In my junior year of college I wrote a small BBS in assembler for my Technical Writing class.
Great machine... I wish I had never given it away. It was very useful. It was fun keeping my dorm mates up all night as they listen to my TTX 1014 daisy wheel printer typing away....
It's Easy To Fix
Because, as you have a vertical line, you must have EHT for the CRT which comes from the line output transformer. This means the line output stage is working, its just the line scan coils that are disconnected, that will almost certainly be a dry joint on the PCB where the scan yoke leads connect or possibly at the scan coupling capacitor or line linearity coil. It can't really be much else other than an o/c scan coupling capacitor.
How do I know this? well, the college I worked for had lots of Osbornes and I used to repair them when they broke down. Most common fault was the extension card for the double density floppies working loose (these things were carried between rooms regularly which probably explains that), next was the display which could fail to work due to dry joints at the line output transistor connections or by the vertical line due to joints as described earlier.
Once I had to make a new system rom for one (by copying a good one from another machine) as the suspect one was partly corrupt (would boot to the Osborne startup screen but would intermittantly fail to load the o/s from disk) -- that took a while to diagnose.
One other task I had to do was calibrate all the floppy drives so that disks were interchangeable between all machines -- there were quite a few that would not reliably read disks from other machines until this was done.
Most of our Osbornes worked with external monitors (to ease eyestrain on the students).
When carrying machines between rooms I always carried two at a time, that way both arms stretched by the same amount :-) happy days indeed.
