Y Combinator's Xerox Alto: restoring the legendary 1970s GUI computer

There are two other things about the alto that have really stuck in my mind. First, the whole thing uses only 300 SSI and MSI TTL chips! No higher order chips (no LSI, much less VLSI).

The other is that the bus bandwidth was only 3/2 the screen update rate. Updating the screen was really important: this was a user-centered, IO-focussed machine which was super radical for its time. If you wanted to do a lot of computation you could steal cycles from the screen update, causing it to go black (in just the bottom half or so IIRC which I probably don't).

Error in the article: I do believe the Alto was the origin of the BITBLT instruction, but it was based on the PDP-10 (PDP-6) block transfer instruction BLT, and the expression blitting was current before the Alto was developed. In fact PARC had a PDP-10 which was the standard research computer at the time -- homemade as well (clones) because at that time Xerox was in the computer business and wanted PARC to use an SDS. (Again this is before my time though MAXC was still running when I was there -- with an Alto as its front end!)

Also contrary to what the article says, the Alto display was not unusual in being portrait mode -- most glass TTYs (think ADM-3A, Hazeltine, VT-52, and I believe the 3270 as well) were taller than they were wide, like a piece of paper. The Alto display was unique, as mentioned, by being bitmapped and black on white. Because of the Alto, bitmapped portrait mode was standard for workstations such as the CADR lisp machines, Bell's BLT terminal, three rivers PERQ, and of course the later PARC computers we used, Dolphins, Dorados (all ECL logic!), Dandelion (sold as the Star). I remember vividly the first landscape machine I used, the Symbolics 3600 in 1985. I didn't, and still don't appreciate the wasted space of landscape displays.

Three-button mice with the mouse buttons arrayed horizontally was also standard because of the Alto. The first time I saw the Macintosh mouse in 84 I was shocked: how could someone use only a one-button mouse? There was a lot of mouse (originally called the "bug") experimentation in the 70s on button count and layout.

The microcode of the alto was compatible with the DG nova as that was the computers used at PARC before the Alto was developed (before my time!).

edit: forgot to mention the origin of blitting.

I'm not sure it cost anyone anything. I mean, a lot of the OSes were/are written in it, so if you were going to go down that path you'd have to not totally forget to add a rather large benefit in the credit side. It's hard to imagine but programming wasn't always about compensating for not quite understanding how the 17 different frameworks you've downloaded from github and dragged into an IDE worked by just getting a faster machine. Once upon a time people had to carefully measure how much to unroll the loop, or how small a lookup table they could get away with before the errors become a problem.

We have two goals. One is to have the restoration chronicled as it goes along, in a way the HN community can discuss and participate in. Obviously we hit the jackpot there, with one of the best technical bloggers in the world.

The other goal is to do something with the Alto that the community will find interesting once it's running. A couple ideas are to make it fetch and render the front page of HN (we'd happily write whatever code was needed to serve it in a suitable format, since HTML is probably a bridge too far), or if we could find a second Alto to communicate with, play Maze War on them (http://www.digibarn.com/collections/games/xerox-maze-war/#ma...). But we'll be eager to hear any suggestions the community comes up with!

As it was mostly used for DTP it made loads of sense.