parse error before '=' token

[Old Wolf]

Those of us programming on PDP-1,5,6,7,8,10,11,12,15,20 etc. machines
long before "CPM/DOS/Windows" know that a CRLF is 15,12.

Are you speaking in octal? Or is that just a coincidence?

 

[Keith Thompson]

Are you speaking in octal? Or is that just a coincidence?

Assembly language on the PDP-11 used octal extensively, mostly because
most of the instruction fields (specifying registers, addressing
modes, etc.) were 3 bits wide. I'm guessing the same was true on the
other machines in the PDP-* series.

(I'm using past tense because these machines are no longer in wide
use, though I suppose some of them are still operational.)

 

[Dave Thompson]

Assembly language on the PDP-11 used octal extensively, mostly because
most of the instruction fields (specifying registers, addressing
modes, etc.) were 3 bits wide. I'm guessing the same was true on the
other machines in the PDP-* series.

More or less. AFAIK no DEC machines except PDP-11 and VAX have
(explicitly coded, mostly orthogonal) modes.

(5 and) 8, and I believe 12 and 15, have 3-bit opcode, and for I/O
6-bit address and 3-bit function(s), but 7-bit local address and no
numbered registers. It also conventionally puts 2 x 6-bit characters
(ASCII 040-137 or special + 040-136) in 12-bit word.

(6 and) 10 have 9-bit opcode, but 4-bit GPR, but extensively uses 2 x
18-bit halfword which breaks nicely in octal, and sometimes uses 6 x
6-bit characters, but also much 5 x 7-bit + 1. There is no PDP-20;
DECsystem-10 and DECsystem-20 are different packagings of PDP-10.

7 (and 9) have 18-bit word, and (usually?) stores characters in either
6-bit bytes or 9-bit halfwords. I don't remember instruction formats.

PDP-1 I never actually saw.

Some DECphiles (or maniacs?) who treasured their feeling of isolation
from and arguably superiority over IBM S/360 felt horribly betrayed
when VAX went almost-fully-byte and hex. At least not bigendian.

(I'm using past tense because these machines are no longer in wide
use, though I suppose some of them are still operational.)

The folks on comp.sys.pdp10 are proud that there are still a handful
of (competitive) clones in real use -- to the absolute purist these
aren't _true_ PDP-10's but to a program, and programmer, they are.
<ObC> The company even funded a gcc port about 2 years back. </>
In addition there seem to be several hobbyist restorations and at
least one museum. As well as several(!) simulators for everyone else.

comp.sys.pdp{11,8} have several active hobbyists and hints of more,
and every few months or so reports of machines or at least parts
becoming available because they are being retired from service,
generally in niche applications that apparently have been undisturbed
-- according to reports in some cases not even cleaned -- for years.

I don't try to follow the VAX and Alpha groups but I expect there are
still noticeable numbers of them. But aren't in the PP list.

- David.Thompson1 at worldnet.att.net