Ultra Geek Out: Homemade CPUs

We have a family friend, Glen, who was an important NASA scientist on the Apollo project. As a mathematician, he invented the idea of using a Fourier Transform to filter data on a digital computer. This was used to filter out signals coming back from in-flight rocket sensors and reduced the data processing time and increased the volume of usable data substantially. Reducing data processing time meant more flights could be scheduled and more adjustments could be done per flight and more things learned from each flight. Processing turnaround was the main bottleneck in the moon program at the time and solving it was the key element in not only winning the race to the moon, but doing it far more safely than would otherwise have been possible.

Glen built his own computer from TTL logic chips back in the early 70s. You programmed it initially by flipping nice thick metal toggle switches. He toggled in an assembler to bootstrap it, and eventually worked his way up to a keyboard and CRT for it. While visiting him one summer, I played an adventure game on it.

Today I read about a teacher in Portland who built a computer not out of TTL logic chips, but out of physical relay switches. He teaches computer architecture and if you want to understand that topic, watch his 1 hr video.

Then visit the web ring of homemade CPUs, linked from the bottom of that page. What fun!

Among the links is this web page:


Yes, that web page is being served to you by a webserver running in Minix, a small Unix, on a computer designed and built by hand using discrete logic units wirewrapped together.

Details of that computer and a photo:


Two-Em Dash

My favorite punctuation mark right now is the two-em dash. There is very little information about this mark on the web, and all of it is incorrect, claiming that the two-em dash is only used to indicate letters that have been left out of a word. I am here to set the record straight.

First, recall how the ellipsis is often misused;— and mis-kerned;— nowadays. A typical misuse is to indicate a pause in voiced or unvoiced conversation:

“I am not sure . . . let me think about it.”

This is unequivocally a complete violation of the proper use of an ellipsis. The ellipsis is correctly used to indicate when part of a quoted text has been left out. Using it for this other purpose leaves us wondering “Is he pausing in speech or is there something he said that the author is not revealing for some reason?” We often can't tell.

Some sort of dash should have been used in the above example instead. One possibility is the two-em dash:

“I am not sure —— let me think about it,” he said reluctantly.

If the person’s pause was not quite so long, the standard em-dash would have been sufficient:

“I am not sure — let me think about it,” he said sincerely.

The two-em dash is for long pauses that exceed the length of a standard em-dash pause. It is also used when you are hiding a person's identity by abbreviating their name, such as,— “During our expedition to Kathmandu, we encountered a Mr. Q——, a former barrister of London, tending mountain goats in a remote valley of the Himalayas.”