I had the fun of programming a this machine at the University of Virginia during the 1970s, and the Grishman book linked there was our textbook. It's a very pleasant and entertaining read.
The key to understanding the architecture is to realize that you are not writing assembly language as much as microcode. I think the architecture would have lasted longer if it had chosen to have registers be a multiple of 8 bits rather than 6. As important as number crunching was to that machine, the limit of 64 characters per 6-bit "byte" was really annoying and made interoperability a mess.
The key to understanding the architecture is to realize that you are not writing assembly language as much as microcode. I think the architecture would have lasted longer if it had chosen to have registers be a multiple of 8 bits rather than 6. As important as number crunching was to that machine, the limit of 64 characters per 6-bit "byte" was really annoying and made interoperability a mess.