Poking Technology's video: Hjalfi writes an assembler

In which yr hmbl svt writes an assembler for a 40-year old operating system because, apparently, none of the ones which came with it were good enough. See http://cowlark.com/2019-06-01-cpm-asm for (a little) more information. This is me writing, in one sitting (not including tea/dinner breaks), a basic but functioning 8080 assembler for the CP/M operating system, from scratch, which runs _on_ CP/M itself, capable of assembling the (almost) original 1978 CP/M source code. Or at least the one bit of it I tried it on. This is part of a slowly ongoing project to produce a completely open source CP/M clone which can be distributed with emulators and the like; while Digital Research have released the source to the original CP/M, it's encumbered with problematic licensing restrictions and so is of very little use except as a reference. The new assembler is written in C and assembled into Z80 machine code with sdcc, for reasons of simplicity. It's currently 1200 loc. A few features are missing, which I intend to work on at some point, but right now it does work. The resulting program is 2-clause BSD licensed. You can find it here: https://github.com/davidgiven/cpmish/blob/master/cpmtools/asm.c Contents: 00:34:00 The lexer 01:36:00 The symbol table 02:07:00 The parser 02:43:14 The expression parser (failed attempt) 03:24:53 The expression parser (actually working this time) 04:25:41 Assembler pseudooperations and bugfixing the expression parser 05:24:00 Start entering 8080 instruction data 06:34:00 Pass 1 complete, begin pass 2 and code emission 05:57:36 First output file created; debugging where it's wrong 07:14:36 It works Production notes: the resulting assembler is about 5.5kB. The recorded video for this session was 80925488kB.