D
Dennis Lee Bieber
Cousin Stanley fed this fish to the penguins on Thursday 15 January
2004 12:33 pm:
My college (now a university) mainframe was a Xerox Sigma-6 (Honeywell
bought out the Xerox line; of course, the Xerox line was bought out
from SDS, which was created by a bunch of IBM renegades -- hence the
use of EBCDIC rather than ASCII <G>). We had a lot of Gandalf
communication racks to handle the terminals (only n-of-M terminals
could be live at a time, the Gandalf stuff controlled allocating
terminals to the mainframe).
One year Honeywell persuaded the college that a Level-6 could be used
to replace most of the inflexible Gandalf gear... As I recall, it was
obtained with pretty much no OS or software -- a system definition file
for the Sigma's Meta-Symbol assembler was used to produce absolute
level-6 binary files (Meta-Symbol was an assembler that did not know
/any/ instruction set natively -- even the Sigma instruction set had to
be loaded using a system definition file -- though "standard
instruction formats" did have predefined "control macros". One defined
an instruction via declarations of the form:
LD cmd,2,3,3 b'01',af(1),af(2)
[note -- that's actually an 8080 MOV instruction masquerading as a
LoaD... cmd defined #bits per field, then we list a constant,
ArgumentField(position)...]).
Back to the Level-6... It worked great as a terminal server... until
the heat built up...
Apparently the main PC cards were mounted horizontally. When they got
warm they'd sag... Whoops, there went the connections to the
backplane... When it came back on-line one often found their terminal
was now connected to a totally different user's process. I once ended
up with a local high-school's account (they were on one of the /five/
dial-up modems that were available).
--
2004 12:33 pm:
Ack... the infamous Level-6...Honeywell also produced a line of mid-range machines
called the Level 6 minicomputers ....
My college (now a university) mainframe was a Xerox Sigma-6 (Honeywell
bought out the Xerox line; of course, the Xerox line was bought out
from SDS, which was created by a bunch of IBM renegades -- hence the
use of EBCDIC rather than ASCII <G>). We had a lot of Gandalf
communication racks to handle the terminals (only n-of-M terminals
could be live at a time, the Gandalf stuff controlled allocating
terminals to the mainframe).
One year Honeywell persuaded the college that a Level-6 could be used
to replace most of the inflexible Gandalf gear... As I recall, it was
obtained with pretty much no OS or software -- a system definition file
for the Sigma's Meta-Symbol assembler was used to produce absolute
level-6 binary files (Meta-Symbol was an assembler that did not know
/any/ instruction set natively -- even the Sigma instruction set had to
be loaded using a system definition file -- though "standard
instruction formats" did have predefined "control macros". One defined
an instruction via declarations of the form:
LD cmd,2,3,3 b'01',af(1),af(2)
[note -- that's actually an 8080 MOV instruction masquerading as a
LoaD... cmd defined #bits per field, then we list a constant,
ArgumentField(position)...]).
Back to the Level-6... It worked great as a terminal server... until
the heat built up...
Apparently the main PC cards were mounted horizontally. When they got
warm they'd sag... Whoops, there went the connections to the
backplane... When it came back on-line one often found their terminal
was now connected to a totally different user's process. I once ended
up with a local high-school's account (they were on one of the /five/
dial-up modems that were available).
--