CXY08 8-Line Asynchronous Multiplexer

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M3119-YA Multiplexer Card

The CXY08 8-Line Asynchronous Multiplexer is a later QBUS equivalent to the UNIBUS DH11 (it is a replacement for the DHQ11). It provided 8 RS-232 asynchronous serial lines. Output used DMA (with each line having its own buffer pointer and count); input used a 256-character FIFO buffer.

Like the DHQ11, it can be set (via a switch) to exactly emulate either a DHV11 or DHU11. It has full modem control.


Physically, the CXY08 consisted of a single quad card, the M3119-YA. It connected to a pair of BC19N-12 distribution cable assemblies (4 lines each); each BC19N ends in four male DB-25 connectors (DB-25P).

Device registers

The registers will depend on whether it is emulating a DHV11 or DHU11.

Further reading

  • CXY08 User's Guide (EK-CXY08-UG) - not available online
  • CXY08 Technical Manual (EK-CXY08-TM) - not available online

External links