Re: Closed system (was: PC connection via twinax ?)

Simon,

Steve wrote:
>>Back in the day when converting from the s36 to 400, there was an ibm 
>>product that allowed data transfer thru the twinax port.  Is it known how 
>>to do that?

You asekd:
>No idea of the top of my head.  But why would that be needed now?  There are 
>better file transfer methods available.  What was at the other end of the 
>twin-ax port to receive the transferred file?

The box was simultaneously connected via twinax to two different hosts.
Basically you took a WS ctl port from host A and a port from host B and ran them
to input ports on the box.  Then there was an output twinax port where you would
put at least one dumb workstation.  Or cable through to more WS's or twinax
printers -- up to the port limit of 7 of course.

The box was a little like a a twinax A/B switch -- but it kept both hosts active
at the same time and enabled a hot key sequence (on dumb terminals!) to switch
between hosts.  Each user on the port could could hot key independently, and
address 0 could also switch printers between hosts.

This made for a good way to perform compatability testing and some initial
training of users prior to cutover.  And it made a much better A/B switch than a
real A/B switch.  I know a software house that used one for years as a
replacment for A/B switches -- maybe they still use it.  (Why anyone would
rather program from a dumb terminal rather than a PC is beyond me, but that's
another story...)

The second function the box provided (other than dynamic A/B switching) was data
transfer.  Software was provided for the S/36 and AS/400 which would use display
sessions as a bi-directional data pipeline.  Many times in those days you did
not have a compatible tape drive on each machine.  This avoided the need to use
tape conversion services.  And you could do something like refresh all your data
files every night from the old production machine to your new box.

You could dedicate up to 6 twinax addresses for data transfer.  It would
configure those as 3180's in order to get 27x132 support so each "screenfull" of
data would be larger and thus improve throughput.

The original model was over $5K, but never sold well.  In 1990 they started
bundling it with some incentive packages to get people to move from the 36 to
the 400.  (I think IBM was overstocked on them...)  That's how I got to use one
for a conversion.  Worked quite well considering the machines had no other
compatible data transfer method.

I think later they did a different model which did not have the A/B switching
features and was strictly a data transfer box.  For old S/36's without network
connections (most of them!) and without compatible tape drives, this may still
be a viable data transfer method.

Doug