Motorola MVME187 User Manual

Floating Point Support

5-11

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. 

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.

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

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). 

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.