AT&T 3B2/300 Technical Reference Manual page 185

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CM195T INTELLIGENT SERIAL CONTROLLER CARD
The CMl 95T Intelligent Serial Controller (ISC) Card is a single-width card measuring 6.5 inches
wide by 7.4 inches deep. The ISC provides for the connection of two serial ports. The CMl 95T Card
is a general purpose, synchronous communications peripheral interface card providing a two channel,
full duplex, synchronous interface. The ISC card supports both synchronous and asynchronous
peripheral device operation. The ISC supports multiple applications depending on the software
executing in the ISC Random Access Memory (RAM). The ISC can provide communication over
synchronous channels such as Systems Network Architecture/Synchronous Data Link Control
(SNA/SDLC), bi-sync, and X.25 as a function of the appropriate software being loaded on the ISC card.
The communications interface cabling provides two DB-25 male connectors. Both of these
connections are RS-232C, Data Terminal Equipment (DTE) connections. Connector pinout information
is provided in Appendix B. Figure 2-54 shows the component layout of a typical CM195T ISC Card.
The major components of the CMl 95T Card are listed below:
• An INTEL 80186 Microprocessor
• 128K bytes of Dynamic Random Access Memory (DRAM)
• 16K or 32K bytes of Read Only Memory (ROM)
• An INTEL 8237 Direct Memory Access Controller (DMAC)
• An INTEL 8274 Universal Synchronous/ Asynchronous Receiver/Transmitter (USART).
EQUIPMENT DESCRIPTION 2-161