On 14/01/2025 20:54, Frank Leonhardt via cctalk wrote:
On 14/01/2025 16:28, Jon Elson via cctalk wrote:
On 1/14/25 03:50, ben via cctalk wrote:
On 2025-01-13 6:55 p.m., Joseph S. Barrera III via cctalk wrote:
I would expect universal condemnation for anyone who would ask if
FLACC
were designed for floppies.
Did mainframes ever have a floppy option?
Do any copies exist and what was the meduium?
IBM 370's had an 8" floppy, but I doubt it was accessible to the OS
or user programs. It was used to load main firmware, emulators and
diagnostics. IBM must have had something at the factory to make
those floppies.
Jon
There were definitely floppy drives in a 3174 (the controller for the
3270 terminals). I never found out what they were for! They were
attached to a 4381 that was running an old 370 assembler program (the
4381 being the last CPU that was was 370 code compatible, or so I was
told). If you're a legacy IBM person, this involved PAMs, and you
probably know which software this is :-)
The 3174 runs firmware that interfaces between the mainframe channel and
the screens. The original 3270 type terminals are pretty dumb. The
connect to the 3174 by co-ax cable which I think runs at 1M/bit/sec. It
displays characters sent to it, and sends keystrokes to the 3174. So the
3174 runs a "control program" which manages the terminals. It keeps a
map of the screen, receives and stores characters and sends them to the
mainframe only when a key which requires an interaction is pressed. The
floppies in the 3174 are not accessible by the mainframe.
In fact a 3174 can do quite a few things. It can also do Telnet and ANSI
terminal emulation to a UNIX or VMS host. There is a key which allows
the user to rotate round the sessions. It can also connect to the
mainframe by BI-SYNC, SDLC/SNA, X.25 or Token Ring. Versatile but slow.
Dave
