CASE / Cray System Centre ethernet hub/switch

This network device is rather more impressive than it actually is, but it is still quite interesting. It is labelled on the front panel as being made by CASE technology (who seem to have gone out of business so long ago I cannot find a trace), but the internal blade pcbs are labelled as being made by CRAY Communications or Networks and refers to Denmark Copyright 1982.

It is a chassis based device with up to four power supplies, although only two are fitted to this one. There is a front panel LCD display which shows some configs and allows an ip address to be set using the cursor keys under the display, so this is a semi managed chassis, but certainly not very smart.

There is a 25 pin D socket located under the right hand side top panel (underneath the word “system”), it is not at all obvious and is a serial management port.

It has an unusual combination of RJ45 based 10MB/s ethernet blades which also can have a fibre module fitted, only one blade has this on mine, and a (IBM) 3270 Terminal server blade with 8 BNC sockets and one AUI socket. Curiously, this card is labelled on the pcb as being a 3270 / 5250 Terminal server, so maybe it could talk to AS400 based systems as well as the earlier IBM mainframes.

Ethernet ports

The ethernet blades seem to be grouped in threes, one master blades and two slave blades. The master blades have a daughter card fitted which seems to be a microcontroller board with associated ethernet controllers, at a first glance, I thought the three cards were linked together as a single hub, with a switched uplink to the backplane, but looking at the chipset, I am now uncertain.

I have attached the appropriate data sheets for both the two microcontollers, and AMD MACH130 32 bit Programable Logic Array, and the two National Semiconductor devices.

3270 Terminal server

This is the more interesting part in many ways. It appears to provide 8 coax based lines to 3270 terminals ( https://en.wikipedia.org/wiki/IBM_3270 ) and has an AUI port for ethernet.

The coax ports look a bit like thin ethernet, but as can be seen they are driven by a DS3487 chip which is a tri-level driver and nothing to do with ethernet. Also the board has a DP8344 chip which is a Biphase Communications Processor. Both these are made by National Semiconductor. From the data sheet, “The DP8344B BCP is a communications processor designed to efficiently process IBM 3270 3299 and 5250 communications protocols.” A drawing on this sheet also shows the circuitry for either coax or a twinax line driver.

Other interesting chips are am LSI LR3300, a 32 bit RISC microprocessor, two AMD MACH130 Programmable Array Logic & two MACH110 PLA, and a NatSemi DS83932 SONIC ethernet controller for the AUI port.