DR750 General Purpose Interface

The DR750 General Purpose Interface provided a high-performance parallel interface, the DR32 Device Interconnect (DDI), for the VAX-11/750, connected to its CMI. The DR32 may be used to connect to high-speed customer equipment; alternatively, two may be used to connect two /750's to each other. It is uncertain if a maximum of one DR780 was supported per machine; DEC documentation does not discuss this point.

The DR750 was implemented on a extended hex card, the L0014, which mounts in the VAX-11/750 backplane, in one of the three CMI option slots, slots 9, 8, and 7. (The DR750 requires replacement of the CMK (DC623) gate array chip on the KA750's Memory Interconnect (MIC, L0003) module with a CML (DC651) chip.)

Three flat cables connect to that slot on the back of the backplane; those carry the DR750 input/output to an 'External I/O Panel' in the back of the cabinet. From there, a BC06V cable (the same cable as on the DR780 connects to the user equipment.

See also

• DR780 High-Performance Channel Interface

Further reading

• DR750 General Purpose Interface User Guide (EK-DR750-UG-001) - not available online

External links

• VAX Maintenance Handbook VAX-11/750 (EK-VAXV3-HB-001) - contains a section on the DR750 on pp. 44-49 (pp. 56-61 of the PDF)