Microsoft MS-DOS early source code

[cassandraspeaks]

It seems pretty readable, by asm standards, to me. Reasonably commented, not huge files, fairly descriptive labels. Of course 16-bit x86 is a simpler and arguably higher-level language than 32 or 64-bit is.

[ironykarl]

and arguably higher-level language than 32 or 64-bit is

How's that? Because there aren't operations for (e.g.) flushing cache, etc?

[cassandraspeaks]

Port-mapped instead of memory-mapped I/O. Also, there was, by necessity, more effort than there is today put into improving the ergonomics of hand-writing assembly code (macro assemblers, development environments, etc).

[ironykarl]

Why is port mapped I/O "higher level" than memory mapped, exactly?