25 Jul
1998
25 Jul
'98
6:26 a.m.
It's mostly a problem if there isn't
documentation at the place where
the machine is. I've never run into a machine that is really beyond my
experience (my experience so far is PCs and BASIC-based home micros),
but if I ever had to deal with a PDP, I'd have to spend a lot of time
asking questions here and otherwise. Not that I foresee it. PDP will
eventually vanish from industrial applications, just because they will
all eventually be damaged by floods, fires, etc. And companies go
bankrupt, too. I doubt that by the time I am 50 I will run a reasonable
risk of seeing a PDP. Also, I don't know how to _program_ a PC. I know a
If people like Allison, Tim.Shoppa, John.Wilson, myself and others have
our way, they won't disappear... I have some 16+ -11s of various types
at home (check the home_systems page off my web page)
bit of BASIC (who doesn't?), enough to write a
simple text editor or
something. I'm learning C but am stuck with pointers. I'm going to take
C++ at school starting in the fall. I've tried assembly, and do notice
that it's more straightforward than higher-level languages (I.E. there
are no ambiguous concepts like in C, it's all called what it really is),
but am not much good with things mathematical. Maybe I'll learn.
With older assemblers, it was pretty straightforward. Nowever, with
RISC machines which have pipelines and 'hints' and branch delays, etc.
assembly is a little more difficult. Plus, where the -11 has an
instruction set where you can MOV from memory to memory, memory to
register, register to memory and register to register, the RISC
machines generally forego memory to memory and, like the -8 before
them, require you to move things through a register first...
How many instructions [on the -8]? I believe the
Pentium has on the
order of 80, not sure.
The -8 had 8 general purpose instructions, but it also had things
called operate microinstructions, in groups, which did multiple
things depending on which bits of the instruction were set. So,
for example, you could clear the AC (CLA) and in a separate
instruction OR the contents of the switch register with the AC (OSR),
or you could combine the two operations into one instructions (since
there were members of the same microinstruction group).
There were also the instructions for the various devices, but they
were pretty much similar in actions, but with different device numbers
encoded in them.
Megan Gentry
Former RT-11 Developer
+--------------------------------+-------------------------------------+
| Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry zk3.dec.com |
| Unix Support Engineering Group | (home): mbg world.std.com |
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