[protomikron]

Does anybody know something about the main differences to the first edition? Is it the same HACK computer (and stack, with assembler, high-level language, etc.), or did they change that?

The original architecture had some caveats - e.g. no external interrupt capability, so IO was implemented using busy polling and inspection specific IO-mapped memory regions (I don't blame them, as it made the book more concise and you can not cover everything) and there has been discussion about a HACK-2 from the community, so it would be interesting if somebody knows more.

[bmitc]

I emailed the authors a while back when I found out about the second edition, asking about the differences. They stated that the hardware platform and software stack specifications are unchanged.