@DarvenDissek @sebsauvage The fun part is that #QDOS stood for "Quick and Dirty Operating System" and was a one-person project by somebody who built a CP/M alternative by himself.

#Microsoft bought it for small money, relabeled it as #MSDOS and made their first Millions with it.

Furthermore: #Windows was a rip-off from macOS. And #WindowsNT was a dirty hit in the back while MS was (co-)developing #OS2 for IBM.

Most people don't even know about #Excel and (partly) #Word being a 3rd-party software bought by MS.

The main contribution by MS was not as a software developing company. Their core competence was taking money for something that was for free and widely shared and improved by all sorts of people before. They invented proprietary software, software licenses and mandatory software bundles with hardware with no option not to pay for it.

Whatever software decisions were made on top, were mostly really poor decisions IMO.

@cks

The irony is that the constraint that you're talking about went away in the early 1980s when processors with more than just a single accumulator register became popular.

Sinclair QDOS is another, roughly contemporary but a few years earlier, example. The 68008 had far more general-purpose registers than the Z80, so the system call TRAPs in QDOS uniformly return an error code in D0 and up to three results in D1, D2, and D3.

#QDOS #syscalls #SinclairQL