The Bendix G-15 from 1956, the world’s first “personal computer.” One of these cabinets weighed a literal 1000 lbs. and cost half a million dollars in today’s money. Or you could rent it for the equivalent of $17,000 a month.
It was numeric only, you had to “talk” to it via a typewriter, and when you turned it off it ‘forgot’ everything. It used 'drum memory,’ which used the same rust-covered-spinning-magnetic-thing technology all hard drives would continue to use until flash memory became a thing. But in the Bendix it looked something like this (one from a slightly earlier computer):
This computer is so old no one seems to have figured out what 'bits’ it is. All I know is that drum thing “holds 2,160 words of twenty-nine bits.” It can also do basic math problems in 270 microseconds. …Which sounds fast, but that means it can do 2+2=4 in 27 thousandths of a second. Which is probably exactly how long it took your stupid brain to do that. For slightly more complex math, hiring a human mathematician at this time would be both cheaper and easier than dealing with this computer.
This is a “vacuum tube / diode analog architecture” computer, and it already had some kind of OS that meant you didn’t have to know machine code? But that slowed it down even more…?
I have absolutely no idea how analog computers worked, or how anyone used one. There are tape decks on this thing, and it is plugged into a typewriter. Like I get the digital 1 and 0 thing, but I have no concept how you make light bulbs and blobs of germanium do that electronically.
But someone did, and this eventually led to you streaming Now That’s What I Call Music! No. 86 on a Samsung phone.
So obviously all of this was a good idea…
Hell yeah,
BENDIX G-15!
The Bendix G-15 is indeed a digital computer, despite the vacuum tube construction. The tubes are being driven within a digital domain, high or low – no intentional in-between.
It is worth noting that there a significant number of diodes on board, which save significant weight, power consumption, and size. Here are
mostof the card modules on board that contain the vast majority of the logic. There are other diodes and vacuum tubes inside the chassis for other specific tasks.
The unit here in my pictures belongs to the System Source Computer Museum, which is currently being repaired by Usagi Electric. I visited him recently and took these photos.
See that large non-descript silver box? That’s the memory drum. It’s sealed in there for protection, the motor is behind it.
Here’s the main interface: the typewriter. You don’t interact with it the way you might think of with a teletype. Rather, certain keys correspond to different functions and different bit combinations. To my knowledge, only the alphanumeric-equipped units will let you type characters. The numeric-only units don’t even used most of the keys. Most programs are loaded on by 5-level paper tape, encoded in something other than Baudot.
