Tiny CRT, enormous floppies
Before we crack the case, let's instead lift the latched door on the back of the Osborne 1 and see what it conceals:
Behind the Osborne 1's hinged back door lurks the AC plug, fuses, and on/off switch (click to enlarge)
The answer: not much. There is, however, a tiny bit of nostalgia: an on/off switch that actually says "On" and "Off" in addition to the now-familiar one and zero icons.
Five Phillips screws – two recessed deeply enough to require a six-inch screwdriver – hold the case together. Once I found the right screwdriver and removed them, and unscrewed the panel that held the on/off swith et al., the case came apart easily.
Those full-height floppy drives dwarf the five-inch CRT (click to enlarge)
The cage in which all of the second-generation Osborne 1's electronic goodness resides is an open-frame design. The original Osborne 1 had a cage with closed sides.
You'll notice that once I removed the cage from inside the Osborne 1's plastic case, it sags in the middle – that CRT may be small, but it, its power supply, and its associated electronics are heavy enough to cause the cage to sag.
The floppy drives' ribbon cable dominates the rear view of the component cage (click to enlarge)
In the front view of the cage, you'll notice heavy shielding foil covering the top of the CRT module. In the rear view, I've peeled that foil to one side so that you can catch a glimpse of the CRT assembly – you'll see more photos of that area on a following page.
Full-travel keys have long disappeared from portables – and from most keyboards, for that matter (click to enlarge)
The keyboard case comes apart with the removal of four screws, and freeing the keyboard itself involves four more. The 69-key keyboard was manufactured by Oak Switch Systems (part number 5-64951-022), and the full-travel membrane keys themselves are a blessed throwback to the days when computer keyboards felt more like electric-typewriter keyboards than do the Chiclet-like nubbins on, say, my MacBook Air.
In the image above, notice the little white square on the keyboard base, just right of center. Here's a close-up:
But what month are we talking about? (click to enlarge)
Another square (not shown) gives the year of manufacture. This one apparently has something to do with the day of the month of manufacture. If any Reg reader can offer more info on this detail, I'd love to hear it.
There's plenty of room inside the keyboard's case – and inside the Osborne 1 in general (click to enlarge)
The enormous amount of free space inside the keyboard case allowed for the ribbon cables that carried keystroke info to the black keyboard cable (it starts coiling off-camera) to arc gracefully with no crimping to worry about.
Next page: Port authorities
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.
