Articles by: Phil Ryals

Curious ROM Variant on Apollo Lunar Module

Curious ROM Variant on Apollo Lunar Module

I’ve recently been reading the Operations Handbook for the Apollo Lunar Module (don’t ask), and in it I learned of a read-only memory variant that I was hitherto unaware of. The Apollo Lunar Module (LM) carried two on-board computers:  one in the Primary Guidance & Navigation System, called the LM […]

October 17, 2012 0 comments Read More
Jacquard Looms and Rod ROMs

Jacquard Looms and Rod ROMs

As I described in Dimond Rings and Read-Only Ropes, both of the methods for constructing rope read-only memories had their problems. Those using magnetic toroids for the bit transformers were reliable, but labor intensive to string, and the inevitable stringing errors frequently required extensive rework to correct. Each time the contents were altered also required another test cycle, which led to manufacturing delays and added to the costs.

October 14, 2012 2 comments Read More
Dimond Rings and Read-Only Ropes

Dimond Rings and Read-Only Ropes

From 1969 to 1972 I worked for a computer memory company out in Phoenix, called Quadri Corporation. One of its major product lines was rope (sometimes called core-rope, transformer, or wired-contents) read-only memories.

October 11, 2012 5 comments Read More
RC-3 Relay Computer

RC-3 Relay Computer

September 22, 2012, marked the one-year anniversary of an event that is near and dear to my heart: dedication of the RC-3 Relay Computer. I spent 21 months and more than 1,000 hours working on the design and construction of RC-3 while a volunteer at Goodwill Computer Museum in Austin.

September 28, 2012 6 comments Read More
Digital Spirography & Plotter Art

Digital Spirography & Plotter Art

Many of you may remember the Spirograph, a set of gears and rings that you can use to make interesting patterns composed of curves called trochoids. There was a program for the Macintosh back in the mid-1980s that drew similar appearing figures, called Diatom.

September 26, 2012 0 comments Read More