RCA Spectra 70 Series

[Al Kossow]

The Spectrolas were notable for being fodder for custom microprogramming.

I dug back through the documentation, and I don't see a user microprogrammable hardware option. The hardware docs I have just show machines with 53 bit ROM
Were the small models like the 360/25 where microcode existed in core, and was vertically microprogrammed?

 

[Chuck(G)]

I don't recall. I do remember a red-cover hardbound book from back in the day that discussed the subject. Well over 50 years ago. Probably the 70/45--at the time, there was quite a bit of information wandering around. Here's a sample:

http://rca.vobj.org/RCA%20Engineer/RCA%20Engineer%20v13/RCA%20Engineer%20v13n4/p46FranksWarren-RCASpectraEmulationTechniques.pdf

 

[Al Kossow]

chapter 9 of Husson's microprogramming book

 

[Chuck(G)]

Could be--it was a long time ago and I'm not likely to see a working Spectrola any time soon...