Motorola MVME187 Floating Point Support, Hardware Functions, Exception Vectors Used by 187Bug

Floating Point Support

Hardware Functions

The only hardware resources used by the debugger are the EIA- 232-D ports, which are initialized to interface to the debug terminal and a host. If these ports are reprogrammed, the terminal characteristics must be modified to suit, or the ports should be restored to the debugger-set characteristics prior to reinvoking the debugger.

Note Although the 187Bug does not explicitly manage the MC88200 or MC88204 CMMUs, hardware prevents caching of I/O space on the MVME187, i.e., $FFFXXXXX. Furthermore, the code cache must not be operative for code pages which are being traced or breakpointed.

Exception Vectors Used by 187Bug

The top 16 MC88100 exception vectors (i.e., #496 to 511 inclusive) are reserved for use by the debugger.

CPU/MPU Registers

MPU register CR20 is reserved for usage by the debugger. If CR20 is to be used by the user program, it must be restored prior to utilizing debugger resources (system calls).

Floating Point Support

The floating point Special Function Unit (SFU) of the MC88100 microprocessor chip is supported in 187Bug. For MVME187BUG, the commands MD, MM, RM, and RS have been extended to allow display and modification of floating point data in registers and in memory. Floating point instructions can be assembled and disassembled with the DI option of the MD and MM commands.

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