20 Oct
2011
20 Oct
'11
8:23 p.m.
Sridhar Ayengar wrote:
Eric Smith wrote:
I agree, Eric, that my view of youngest was confusing to you. If I
had provided an example (such as the PDP-11/93), that would have
be easier to understand.
I have six grandchildren. The youngest is 4 years old and the oldest
is 24 years old.
The problem, perhaps, is that the youngest PDP-11/93 is about 20 years
old and the oldest PDP-11/20 is about 40 years old.
More to the point, I was just noting that the STAR100 back in the 1970s
had this 48 bit address for memory when core was so expensive that
4 MB of memory was about the physical limit for that system while at
about the same time, a lowly PDP-11/20 often had just 8 KB or even
4 KB of core memory - yet 20 years later the PDP-11/93 came with
4 MB of memory on the CPU card, but still with a 16 bit program
address even though the physical Qbus address was 22 bits.
Jerome Fine
Jerome H. Fine wrote:
I think you two maybe using different definitions of "young". I find it interesting that the youngest group of
PDP-11 systems
supported
4 MB of memory whereas [...]
I find that statement baffling, as the first PDP-11 to support 4088KB of
memory wasn't introduced until 1975, five years after the introduction
of the PDP-11. I would say that the youngest group of PDP-11 systems
supported 56KB, and slightly less young systems supported 248KB.