Reference Manual

PMAC 2 Software Reference
PMAC Saved Setup Registers 391
on/reset is X:$E00A bits 0 – 7. It is permissible to write to this register directly (suggested M-variable
M94) to change the active setup without a SAVE and reset.
X:$0788 VME Interrupt Level
Range: $01 - $07
Units: None
Default: $02
X:$0788 controls which interrupt level (1 to 7) PMAC will assert on the VME bus. Multiple boards on
the same VME bus may assert the same interrupt level if each one has a unique set of interrupt vectors as
set by X:$0789.
X:$0788 is actually used at power-on/reset only, so to set or change the VME interrupt level, change the
value of X:$0788, store this new value to non-volatile flash memory with the SAVE command, and reset
the card with the $$$ command. The active register into which the value of X:$0788 is copied at power-
on/reset is X:$E00B bits 0 – 7. It is permissible to write to this register directly (suggested M-variable
M95) to change the active setup without a SAVE and reset.
X:$0789 VME Interrupt Vector
Range: $00 - $FF
Units: None
Default: $A1
X:$0789 controls which interrupt vectors will be provided when PMAC asserts a VME bus interrupt. If
PMAC asserts the interrupt to signify that it has read a set of mailbox registers and is ready to accept
another set, the interrupt vector value will be equal to (X:$0789-1). If PMAC asserts the interrupt to
signify that it has written to a set of mailbox registers and is ready for the host computer to read these, the
interrupt vector value will be equal to X:$0789. If PMAC asserts the interrupt to signify that it has put a
line of text in the DPRAM ASCII response buffer and is ready for the host computer to read this, the
interrupt vector value will be equal to (X:$0789+1).
If there are multiple PMAC boards asserting the same interrupt level in the VME bus as set by X:$0788,
they each must assert a unique, non-overlapping set of interrupt vectors.
X:$0789 is actually used at power-on/reset only, so to set or change the VME interrupt vector, change the
value of X:$0789, store this new value to non-volatile flash memory with the SAVE command, and reset
the card with the $$$ command. The active register into which the value of X:$0789 is copied at power-
on/reset is X:$E00C bits 0 – 7.
It is permissible to write to this register directly (suggested M-variable M96) to change the active setup
without a SAVE and reset.
X:$078A VME DPRAM Base Address Bits A23-A20
Range: $00 - $FF
Units: None
Default: $00
X:$078A controls bits A23 through A20 of the VME bus base address of the dual-ported RAM of PMAC.
Bit 3 of X:$0786 corresponds to A20 of the base address, and bit 0 of X:$0786 corresponds to A16.
X:$078A is only used if 24-bit or 32-bit addressing has been selected with X:$0783 and X:$078C.
Bits A19 through A14 of the DPRAM VME base address must be set by the host computer after every
power-on/reset by writing a byte over the bus to the “page select” register in the PMAC’s VME mailbox
IC at the mailbox base address + $0121. This must be done even with the single-page 8k x 16 standard