ST18952 datasheet(42/67 Pages) STMICROELECTRONICS

42 / 67 page

42/66

ST18952

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.

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

ST18952 データシート(PDF) 42 Page - STMicroelectronics