RH750 Massbus Adapter

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The RH750 Massbus Adapter was a MASSBUS device controller for the VAX-11/750's CPU/Memory Interconnect (CMI).

It was implemented on one extended hex card, the L0007 MASSBUS Adapter (MBA), which mounts in the VAX-11/750 backplane in one of the three CMI option slots. A VAX-11/750 could have up to three RH750 Adapters; the first one goes into CMI slot 9, the second into slot 8, and the third in slot 7.

It was common practice to have two separate RH750s, one for tape, and another for disk devices. Combining both on one RH750 was possible, but tape usage had a negative impact on disk performance.

Further reading

  • RH750 Massbus Adapter Technical Description (EK-RH750-TD) - not available online
  • VAX Hardware Handbook (1980-81) (EB-17281-20) - the RH750 is covered in some detail in Chapter 10, pp. 175-190

External links