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computing, today vs yesteryear, atari st 

this PDF of this book I've been virtually thumbing through on the Atari ST internals is wild through a modern lens.

it was contemporary to the machine itself, so it was for all intents and purposes examining a new thing in as much technical detail as it could. as you'd expect.

then I scroll to page 275 of the PDF and am presented with Section 3.9 - The BIOS Listings - Version 1, which appears to be a full disassembly of the system BIOS along with comments throughout explaining what was (supposed to be) happening on that line

highly secure: can't jailbreak what's already unlocked :blobthinksmart:

if you like to nerd out reading 68000 assembler, this link's for you

synacktiv.com/ressources/Atari

re: computing, today vs yesteryear, atari st 

@djsundog It's a bit ironic though, as the ST BIOS code was written in C. So what you're looking at is annotated assembly that came out of a C compiler.

re: computing, today vs yesteryear, atari st 

@loke @djsundog GEM had C interfaces, but TOS was written in assembler (ported from the GEM x86 code).

Even better, you can find those sources (Caldera made them GPL licensed).

deltasoft.com/downloads-gemwor

re: computing, today vs yesteryear, atari st 

@loke @djsundog If you love looking at source code for classic machines there was also books written about the ZX Spectrum OS, the ZX81 OS, and the Atari DOS and BASIC.

re: computing, today vs yesteryear, atari st 

@loke @djsundog Even better: there's a clean-room implementation of GEM on the Atari ST called EmuTOS, so you can look at an implementation in C.

emutos.sourceforge.io/

re: computing, today vs yesteryear, atari st 

@loke @djsundog (And yes, I too have been bitten by the Atari ST bug as of late. 30 years too late, to be precise)

re: computing, today vs yesteryear, atari st 

@craigmaloney @loke see, it's nice not being alone ;)

re: computing, today vs yesteryear, atari st 

@craigmaloney @loke @djsundog GEM was never written in assembly, it always was in C, even on x86. The VDI's predecessor, GSX, however, was written in assembly, by necessity to fit on 8080 systems of the day.

Perhaps folks are confusing GEM with GEMDOS? But, even then, by the time that was released, DRI had transitioned away from PL/M and assembly and started using C for most products. I'd be genuinely impressed if DRI chose to write GEMDOS in assembly. CP/M-68k already existed at that time, and was their first major product written in C.

re: computing, today vs yesteryear, atari st 

@vertigo @loke @djsundog Let's both be right:

deltasoft.com/downloads-gemwor

Looks like a combination of x86 assembler and C code.

re: computing, today vs yesteryear, atari st 

@craigmaloney @djsundog Was it? Back in the day I remember being surprised at how it was written in C. It was a big thing back then, as it was the first home computer whose operating system was not written in assembler.

re: computing, today vs yesteryear, atari st 

@loke @djsundog It's got both in there.

One of the best articles I've found on the relationship between DRI and Atari during the ST was this one (two parter):

dadhacker-125488.ingress-alpha

Lots of amazing stuff in there about what went where, and how "portable" GEM was.

So yes, lots of it was in C, but there was still assembly in there that needed to be dealt with.

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