>>>>> "DS" == Dan Sugalski <[EMAIL PROTECTED]> writes:
DS> One needs to specify *which* PDP is the target. The PDP-11 was the
DS> most popular of the bunch, and it's a 16-bit machine. One of the
DS> TOPS machines was 36 bit, IIRC, with either 7 or 9 bit
DS> chars. (Can't remember which)
i don't think we have to worry about the pdp-11 much. :) but in any case
i think c compilers for it did support a 32 bit long. the bigger issue
is the 64k address space. i doubt we can get perl to work there without
overlays and we don't want to go there. :)
the dec 10 and 20's had 36 bit words with an 18 bit address space which
is also somewhat limited. they had NO fixed character size but actually
supported a variable byte size with a special pointer that had the size
and bit offset into the current word as well as the address. this was
supported with byte inc/dec but random access was problematical then.
i used a c compiler on a tops-20 system that just didn't try to fight
it. it used the whole 36 bit word for each char. that gave random and
sequential char access at a great cost of memory. i don't know how gnu
is planning on dealing with this issue. maybe they would settle on a 9
bit char and get random char access with some minor overhead and the
sequential stuff still works.
also is there a market for dec 10/20's today? i believe until a few
years ago compuserv ran on them and they (or someone) bought the design
from dec to keep building them just for that market. if gnu cc works on
a 20 then we can just use its support and hopefully not make special
cases for its INT. one unsual point is that the 10/20's address size is
smaller than its integer size (18 vs. 36 bit) but its pointer uses 36
bits (half for the address, the other for indirection or byte info).
it all brings back memories ...
uri
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