Here's one way to avoid going into detail on ELF: https://news.ycombinator.com/item?id=38592000

"(nearly) constant" means you can pick either (a) a constant blob, at the cost of a fixed image size, à la COM, or (b) patch up length (one or two places, iirc) if you're feeling fancy.

In one of my other compiler books (http://t3x.org/t3x/book.html) I just use a template for the ELF header, but I still think it adds too much complexity. One reader complained about it.

found it: elfheader() in https://t3x.org/t3x/t.t.html

fwiw, I think you commented it very nicely; de gustibus!

Did you come up with if vs. ie ... else ... independently or inherit it from BCPL?

> fwiw, I think you commented it very nicely;

Thanks, I thought so, too, but I can also understand that the comments are not very helpful, if you know nothing about linkers, paging, and object files.

I think I adopted IE/ELSE from BCPL, but thought that IE is nicer than TEST, because it is itself short for If/Else and because it looks almost like IF.

> de gustibus!

Funny, I just started to brush up my Latin! :)

Having very much enjoyed LFN, I think your taste in where to simplify suits me, at least.

I doubt I'll ever get around to it but I'm sort of tempted to see if I can remember enough arm26 assembler to try and get it to compile to that (arm26 does have multiply but not divide, I'd have to dig out the 'standard' fast division asm block that was passed around amongst Archimedes authors back when that was my primary platform).

Just bought a copy so I should at least get as far as "I've read the book but not got around to the arm26 part" though :D

What is ARM26? I know ARMv6, and a T3X/0 back end for the ARMv6 would be seriously cool. So cool in fact that I might write it myself. :) Here is an unsigned divide for the ARMv6 that I borrowed for the SubC compiler: http://me.henri.net/fp-div.html In fact the sources for the SubC compiler might serve as a pretty good foundation for porting T3X/0 to the ARMv6.

The ARM 2 chip in the early Archimedes machines was a 32-bit chip with 26-bit addressing so it got referred to as arm26 assembler (I'm not sure if that's technically -correct-, but I'm pretty sure it was in the title of the book I learned from and there's a directory in linux kernels that support that arch called asm-arm26 at least, so my memory isn't -just- making it up ;).

I would align with this philosophy as it relates to learning. Complexity is a likely a necessity of technological advancement, but a hinderance to 'from-scratch' learning. Abstractions hide many details that may not be needed to operate, but are needed to understand.

The entire retro-computing field is interesting and a bit surprising in it's strength. I would not have guessed that in 2023 an IMSAI 8080 would be selling for ~$3-5k, and that there would be such an active community of people doing things in CP/M. Nor would I guess that I would be working on either of these!

One of the most enjoyable personal projects that I have worked on was the creation and implementation of a CPU, starting with the concept ISA and building the microarchitecture, making lots of cool mistakes that require rework, and eventually having a booting CPU running code in an assembly language of my own. While the performance of a CPU like this is closer to the computational power of my coffee maker, it is still an excellent experience.

I ordered my copy of your book and am looking forward to reading it!