gslick
Veteran Member
It took some looking around to find the DSSI bus pinout documented anywhere. I finally found one place that it is documented in the KA640 CPU Module Technical Manual. Is there a DSSI specification available anywhere?
EK-KA640-TM-001_Tech_Sep88.pdf
Table 2-3 DSSI Connector (J2-Upper) Pinouts
(The table starts at Pin 51 instead of Pin 1 because it is a dual stack of 50-pin connectors)
On the first 11 positions GND is on the even pins. On the middle 3 positions Termination Power is on both the even and odd pins. On the last 11 positions GND flips to the odd pins.
With a 12-29258-01 DSSI terminator attached to DSSI bulkhead connector I measured around 95 Ohms from each of the signal pins (even those listed as Unused in the table) to GND, and around 87 Ohms from each signal pin to Termination Power. Those values don't seem to agree with the data I found for the SIP terminator arrays on one of my M7769 KFQSA boards. I should pull one of them off and measure it, and cross check against one of my other M7769 KFQSA boards.
EK-KA640-TM-001_Tech_Sep88.pdf
Table 2-3 DSSI Connector (J2-Upper) Pinouts
(The table starts at Pin 51 instead of Pin 1 because it is a dual stack of 50-pin connectors)
On the first 11 positions GND is on the even pins. On the middle 3 positions Termination Power is on both the even and odd pins. On the last 11 positions GND flips to the odd pins.
With a 12-29258-01 DSSI terminator attached to DSSI bulkhead connector I measured around 95 Ohms from each of the signal pins (even those listed as Unused in the table) to GND, and around 87 Ohms from each signal pin to Termination Power. Those values don't seem to agree with the data I found for the SIP terminator arrays on one of my M7769 KFQSA boards. I should pull one of them off and measure it, and cross check against one of my other M7769 KFQSA boards.