Motorola MVME187 manual Global Control and Status Register GCSR Method

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Debugger General Information

Global Control and Status Register (GCSR) Method

A remote processor can initiate program execution in the local MVME187 dual-port RAM by issuing a remote GO command using the VMEchip2 Global Control and Status Registers (GCSR).

1.The remote processor places the MVME187 execution address in general purpose registers 0 and 1 (GPCSR0 and GPCSR1).

2.The remote processor then sets bit 8 (SIG0) of the VMEchip2 LM/SIG register.

3.This causes the MVME187 to install breakpoints and begin execution. The result is identical to the MPCR method (with status code B) described in the previous section.

The GCSR registers are accessed in the VMEbus short I/O space. Each general purpose register is two bytes wide, occurring at an even address.

The general purpose register number 0 is at an offset of $8 (local bus) or $4 (VMEbus) from the start of the GCSR registers. The local bus base address for the GCSR is $FFF40100. The VMEbus base address for the GCSR depends on the group select value and the board select value programmed in the Local Control and Status Registers (LCSR) of the MVME187. The execution address is formed by reading the GCSR general purpose registers in the following manner:

GPCSR0	used as the upper 16 bits of the address
GPCSR1	used as the lower 16 bits of the address

The address appears as:

GPCSR0 GPCSR1

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