AT&T 3B2/300 Technical Reference Manual page 468

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CM195K EXPANSION DISK CONTROLLER CARD
General
The CMl 95K Expansion Disk Controller (XDC) Card is an intelligent feature card used to interface a
maximum of two external hard disk drives to a 382 computer. The interface is ST-506. Figure 3-67 is a
functional block diagram of the XDC card. The XDC card consists of the Common Input/Output (CIO)
circuits and the Disk Interface circuits. The CIO circuits include the following:
• INTEL 80186 Microprocessor
• Input/Output (I/0) Bus Control
• Identification/Vector (ID /Vector) Register
• Page Register
• Peripheral Control and Status Register (PCSR)
• Local Random Access Memory (RAM)
• Local Read Only Memory (ROM)
• Miscellaneous Circuits.
The Disk Interface circuits include the following:
• Hard Disk Controller
• Data Separator
• Write Precompensation.
FUNCTIONAL DESCRIPTION 3-215