Primordial USB on Atari 8-bits
When you looking at the Atari 8-bit computers now, it is hard to image how much more advanced they were than the other personal computers available in late 1979. Sure, the Apple II was the one to beat, but the Atari 800 certainly did so, in nearly every way.
Atari graphics obviously blew away everything else out there with its 128 colors (updated to 256 within a couple years) and resolutions up to 320x192. The Atari 800 was particular well designed with a full-stroke keyboard and some expandability. The Atari 400 was low-priced and more affordable, but it’s keyboard was finger-bleedingly terrible.
The Atari computers were also delivered as a complete product line with a variety of hardware peripherals available at the start, including a disk drive, cassette drive, printers, interface expansion and modems. And all of these connected using a safe, easy-to-plug-in connector called a serial bus now know as SIO, which stands for Serial Input/Output.
Unlike other computers that often had a different port for each device, one for disk drive, one for cassette, one for printer, the Atari had just a single SIO port on the side for its IO (not counting the joystick ports, which could actually also do IO).
Above is an SIO cable. Yes, the connectors were bulky but their asymmetrical design meant there was only one way to plug them in and it was easer to figure out. It took a little effort to plug in, but everything is big and easy to grip — just a little push a wiggle will get it done.
This is a closeup of one end of the SIO cable where you can see it is actually made of up a bunch of pins in the connector.
Peripherals would be daisy chained, one after another, all using the same port. The port was safe as well. Unlike other computers you could plug and unplug devices with the computer on. Try that on an Atari ST and you might cause a short!
I don’t have an Atari 800, but this is the SIO port on my 130XE (where it is in the back instead of on the side). That fat connector just gets shoved into this port. It’s a little hard to see, but the label under it says “Peripheral”.
The port could run at up to 19200 bps, which was a reasonable speed back then, faster than the glacial Commodore drives, but slower than Apple II drives.
SIO is so well-designed that the SDrive Max and FujiNet connect to it, effectively each acting as an Atari peripheral.
SIO was created to deal with FCC regulations of the time. I’m not exactly sure how Apple was able to circumvent them by using fragile ribbon cables to connect things, but Atari wanted something more robust and not susceptible to radio interference.
Joe Decuir led the team that designed SIO (and other things) for the Atari 8-bit computers and he went on to help work on the USB standard that would be released in the 90s. He even credits SIO as the basic for USB.
You can certainly see the similarlies. They are both serial-based, with a single port, plug-and-play design and support for daisy-chaining (although hubs were more common with USB). Of course, even if other serial busses of the time had their own similarities, the Atari SIO just feels like a more reasonable ancestor of USB, even in its primitive form.
A few years ago Joe Decuir did a presentation at VCF East where he talked about his time working on the Atari 8-bit computers. Check it out below:
The presentation almost 80 mins, with Joe Decuir talking about:
How he got to Atari
What they learned from the 2600 that informed the 400/800
What they wanted to accomplish, which was different from what they actually accomplished
What they designed: Hardware & Software
What happened in the market and industry
What they learned from that, which led to the Amiga computer
Where they are now
Partial Design Credits
Here are some more interesting links on the SIO topic: