Reference Manual

PMAC 2 Software Reference
392 PMAC Saved Setup Registers
DPRAM option. With the extended DPRAM option, the host computer must write to the page select
register every time a new page is accessed.
X:$078A is actually used at power-on/reset only, so to set or change bits 8 to 15 of the VME bus DPRAM
base address, change the value of X:$078A, store this new value to non-volatile flash memory with the
SAVE command, and reset the card with the $$$ command. The active register into which the value of
X:$078A is copied at power-on/reset is X:$E00D bits 0 – 7. It is permissible to write to this register
directly (suggested M-variable M97) to change the active setup without a SAVE and reset.
X:$078B VME DPRAM Enable
Range: $00 - $FF
Units: None
Default: $60
X:$078B controls whether VME access to the DPRAM IC on the PMAC is enabled or not. It should be
set to $60 if DPRAM is not present to disable access; it should be set to $E0 if DPRAM is present to
enable access.
X:$078B is actually used at power-on/reset only, so to set or change the DPRAM enabling, change the
value of X:$078B, store this new value to non-volatile flash memory with the SAVE command, and reset
the card with the $$$ command. The active register into which the value of X:$078B is copied at power-
on/reset is X:$E00E bits 0 – 7. It is permissible to write to this register directly (suggested M-variable
M98) to change the active setup without a SAVE and reset.
X:$078C VME Address Width Control
Range: $00 - $FF
Units: None
Default: $10
X:$078C controls the VME bus address width, with or without DPRAM. It should take one of six values
in normal use:
• X:$078C = $00: 32-bit addressing, no DPRAM
• X:$078C = $10: 24-bit addressing, no DPRAM
• X:$078C = $30: 16-bit addressing, no DPRAM
• X:$078C = $80: 32-bit addressing, with DPRAM
• X:$078C = $90: 24-bit addressing, with DPRAM
• X:$078C = $B0: 16-bit addressing, with DPRAM
X:$078C is actually used at power-on/reset only, so to set or change the VME bus address width, change
the value of X:$078C, store this new value to non-volatile flash memory with the SAVE command, and
reset the card with the $$$ command. The active register into which the value of X:$078C is copied at
power-on/reset is X:$E00F bits 0 – 7. It is permissible to write to this register directly (suggested M-
variable M99) to change the active setup without a SAVE and reset.