3 Aug
2008
3 Aug
'08
10:56 p.m.
Roy J. Tellason wrote:
On Sunday 03 August 2008 22:57, Jim Brain wrote:
specific devices. Not likely applications. Or were they handling their own
I/O?
I think, at the time in Intel history, I would not fault the designer
for assuming there was no OS or there was no guarantee an OS would be
calling the shots. I'm not sure of who was first (MOS, Moto, Intel,
others), but I know the 6502 did not assume an OS, and I think the 8080
was a bit older than the 6502.
I found the 8080 (but more so the z80) to be of some
interest, but porting
all existing apps to newer chips never made all that much sense to me,
considering the other differences besides the CPU chip. More available RAM,
a lot more standardization of system architecture, a lot more common
standard hardware, and all sorts of other stuff. It was no surprise to me
at all to see lots and lots of newer apps and I don't recall seeing all that
much that got ported over, or at least not that much that I knew about. And
yet that backward compatibility seems to have been an issue for a lot of the
designers for some reason.
Even today, when we design a new X, it's very important to ensure that X
is backwards compatible with X-1, even though we are sure that few will
care. I would go so far as to label designs that were not backwards
compatible (without good reasons) with the moniker we're discussing
here. Note that the designer ensuring backwards compatibility is not
the same as encouraging it. Still, it's drilled into a designer's
head. Don't break compatibility unless there a *VERY* good reason.
Jim