On Oct 17, 2011, at 9:28 AM, Dave Tweed wrote:

> no one did the PDP-11 except for DEC itself, with the LSI-11 (not
> really a single-chip processor) and the J-11.

There was also (from DEC) the T-11, which was a single-chip LSI-11 =20
(somewhat notable for its direct DRAM access that provided RAS and =20
CAS, and multiplexed odd and even address bits on the bus, permitting =20
direct connections to DRAM of various sizes.)  The J-11 was co-=20
developed with Harris; a monster of hybrid package with two big chips.


> I understand that the TI MSP430 has a very PDP-11-like "feel" to it.

Yes.  Very much so.

Intersil and Harris did the 6100 PDP-8 clones.

The thing about the pdp-11 was that it was held up as a sort of holy =20
grail of elegant architectures.  I don't think there was a =20
microprocessor released in the 70s or 80s that didn't say somewhere in =20
the marketing literature "PDP-11-like architetcure" or similar.  Maybe =20
it was wonderfully elegant but not really all that good?  Maybe =20
suffering from insufficient effort?  The T-11 came out in 1981 and ran =20
at 2.5MHz, putting it well behind "state of the art" (8MHz 68000 in =20
the similar timeframe.)  Perhaps it's a matter of scale.  "Everything" =20
was done on a couple of well-known architectures in those days, but =20
"those days" didn't last very long, and the "lots of software for that =20
architecture" is actually dwarfed by SW written since.  I mean, the =20
PDP11 came out in 1970 and was pretty architecturally dead by 1981, =20
whereas the x86 came out in 1980 and is still around...

BillW

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