15 Oct
2012
15 Oct
'12
11:34 a.m.
On 10/15/2012 01:48 PM, David Riley wrote:
Those systems also all had virtual memory subsystems;
the Mac and
the PC didn't have MMUs until the 68020 and 286, respectively (and
even then, the Apple/Motorola PMMU kind of sucked, and 286 Protected
Mode wasn't quite real MMU action). All that is not to say that
doing multitasking without paged MMUs in a small memory footprint
is impossible, since plenty of OSes did so, but it's a barrier to
the lazy programmer.
Very true. I do multitasking all day long without an MMU, on ARM7s,
with (on the big ones) 64KB. Works great here! I see no *real* excuse
other than laziness. There were some highly talented programmers back then.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA