ST18952 View Datasheet(PDF) - STMicroelectronics
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MFG CO.
'ST18952' PDF : 67 Pages View PDF
ST18952
11 External Coprocessor
Dedicated co-processors can be designed by SGS-Thomson, by customer request.
The D950Core instruction set includes two co-processor dedicated one-word instructions,
allowing one (COPS) or two (COPD) parallel data moves between X or Y-memory space and
co-processor registers.
While a co-processor instruction is decoded by the D950Core, the VCI output is asserted high,
indicating to the co-processor that such an instruction will be executed at the next cycle.
Control and status registers, at least one of each, must be included in the co-processor. This
allows initialization in various operating modes and gives information to the D950Core on
operations in progress and status.
An external coprocessor can only be used when program and data bus extensions are
enabled.
12 System Control
System control is provided by glue logic and performs the following functions:
• Control of bus extensions and multiplexing of BSU and X extension IO’s.
• Interrupt vector management (in case of interrupt controller inhibition)
• Control of input clock frequency
• Test control management
• Bus requests (Hold) arbitration
• Buffering
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