I’d call the Inmos B004 the “mother of all Interface cards”, simply because it was the first ISA card sold by INMOS. And it wasn’t just the card but it also defined the (PC) standard of the software interface, mostly called the “B004-interface”. What a surprise 😉
So being the first card, it is quite big (full ISA length) while not offering really impressing specs: 8bit XT Bus, just one Transputer –TRAMs weren’t invented yet- and a max. of 2MB RAM (DILs). To do it justice, the manual rightfully calls it “Evaluation Board” and for that purpose it’s totally fine – remember that 2MB were quite an amount of RAM back in 1984.
To create a multi-Transputer network you had to either plug-in multiple B004s or connect an external network to the onboard connectors (the blue ones in the picture below).
As mentioned, the B004 software interface is what makes this card a keystone in the Transputer universe. All communication to the host (i.e. the XT/AT compatible PC) is done through a port range normally beginning at 0x150 (base, can be moved by some cards).
With certain offsets the host software can communicate with the Transputer, or the C011 to be precise:
|+0x00||C011/12 input data||read|
|+0x01||C011/12 Output data||write|
|+0x02||C011/12 input status register||read = returns input status
write = set input interrupt on/off
|+0x03||C011/12 Output status register||read = returns output status
write = set output interrupt on/off
|+0x10||Reset/Error register||write: Reset Transputer & C011/12 and possibly subsystem (check manual)
read: Get Error status
|+0x11||Analyse register||(un)set analyse|
This mapping was used by more or less all ISA interface cards and extended by other more sophisticated interface cards later.
Needless to say, that very soon there were a couple of “inspired” models from other manufacturers. AFAIK all of them support Transputers up to 30MHz, which the B004 didn’t… so they’re actually better.
This example is from Microway (yes, those guys who later build the i860 Number Smasher), named Monoputer and dated 1987. Up to 2MB could be used on it. Mind the connectors being accessible from the outside:
Later they produced the “Monoputer 2” which was more modern and used SIMM RAM modules instead of DIL parts. The Transputer and Linkinterface moved into the middle of the card and the link connectors were moved inside the pc case again – the connectors are the very same used on the NumberSmasher860:
And here’s the one Transtech made, calling it TMB04 mind the SIMM banks which enable the card to give home up to 16MB RAM (at 3 cycle speed!):