DN11 Automatic Calling Unit Interface

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The DN11 Automatic Calling Unit Interface was a UNIBUS device which connected to, and allowed control of, a Bell 801 Automatic Calling Unit. The ACU could dial a telephone call on an attached telephone line; once the call had connected, a modem attached to the line, in parallel with the ACU, could establish a data link between the local modem and a remote modem. (A serial interface is required to connect the UNIBUS to the modem; that can be either asynchronous or synchronous.)


Each DN11 has a single control and status register. All the DN11s in a single backplane share an interrupt.


A DNll requires a custom quad system unit backplane and support boards (the ensemble is denominated a 'DNl1-AA), which can hold up to 4 independent DN11 plug-in units (DN11-DA). The DNll-AA contains:

Later versions included instead the later revision M7821 Interrupt Control. Each DN11-DA contains:

  • M7226 Control Module (dual-width)
  • BCO1R Cable Card Assembly

See also

Further reading

  • DN11 User Manual (EK-ODN11-OP - not online)
  • DN11 Automatic Calling Unit Interface Manual (EK-ODN11-TM-002 - not online)
  • DN11 Maintenance Prints (MP-DN11-00 - not online)

External links