Northern Telecom BCS35 Replacement Manual page 181

MODEM
MOdulator/DEModulator
A device which modulates and demodulates signals for transmission and
reception, respectively, over communication facilities. A modem allows
digital signals to be sent over analog lines.
PIO
Port Input/Output
A device on the DPP CPU circuit pack that controls a communications bus
between the DPP processors.
RAM
Random Access Memory
A static, read/write memory system in which information is stored in
discrete, individually addressable locations such that access time is
independent of location.
SIO
Serial Input/Output
Circuitry in the DPP that passes data from the DPP to external devices. The
DPP employs four such circuits in its serial I/O circuit pack that provides
communications paths between the DPP and DMS–100/DPP maintenance
interface, the DPP EAT, and the remote polling center link (BCS25–26).
DPP Card Replacement Guide BCS35 and up
List of terms 18–165