Jnc: Somewhat stubby, but I'm not interested enough to fill it out more

2024-06-03T15:39:22Z

Somewhat stubby, but I'm not interested enough to fill it out more

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The '''DR750 General Purpose Interface''' provided a high-performance [[parallel interface]], the [[DR32 Device Interconnect]] (DDI), for the [[VAX-11/750]], connected to its [[CPU/Memory Interconnect|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; [[Digital Equipment Corporation|DEC]] documentation does not discuss this point.

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

Three [[flat cable]]s 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 High-Performance Channel Interface|DR780]] connects to the user equipment.

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==See also==

* [[DR780 High-Performance Channel Interface]]

==Further reading==

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

==External links==

* [https://vt100.net/mirror/antonio/ek-vaxv3-hb-001.pdf 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)

[[Category: DEC Parallel Interfaces]]
[[Category: CMI]]

DR750 General Purpose Interface - Revision history

Jnc: Somewhat stubby, but I'm not interested enough to fill it out more