>> We have a stack of 3/50 and 3/60 bases in reserve.  Unfortunately,
>> in our application of them as X-terminals, the monitors seem to die
>> long before the CPU's, so we have an excess of the bases.

Pity you're so far away, or I'd offer to take 'em off your hands :-)

>> Instead of thinking of them as workstations, I'd like to be able to
>> access their 2 ( or 4 ) serial ports, and scsi port over the
>> ethernet.
> Two.  Four?  Just two.

Four.  Two of them use (I think) TTL-level signals, for talking to the
mouse and keyboard, but if you throw a couple of op-amps on there as
level shifters, there's no reason they couldn't be used as ordinary
serial ports.  (You'd probably have to live without modem control
lines.)  See sys/arch/sun3/conf/FOUR_TTYS.

>> 2) How crazy would it be to try to drive the pins on the scsi port
>> to use as a parallel printer port.  If not impossible, how fast
>> could this be?

I'd say it's crazy alright.  It depends on the SCSI interface being
really stupid, since it amounts to letting the cpu drive the data lines
more or less directly.  A smart SCSI interface is going to want to
speak SCSI, relieving the cpu of some of the SCSI protocol burden.

And as Kevin Neal mentioned, the signal levels and termination and such
may be completely incompatible; you may have to add glue electronics to
deal with those differences.

>> 3) If not, how about a more intelligent scsi -to - printer interface?
> Why not get a serial-to-parallel converter?

Well, I ain't the person who wanted to do this, but my guess would
"speed".  Serial lines on the sun3 can do 38400, maybe 76800.  Bits per
second.  The SCSI bus is capable of more like multiple mega_bytes_ per
second.

					der Mouse

			       mouse@rodents.montreal.qc.ca
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