Reference Manual

Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 80
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 (I96+1).
If there are multiple Turbo PMAC boards asserting the same interrupt level in the VME bus as set by I95,
they each must assert a unique, non-overlapping set of interrupt vectors.
I96 is actually used at power-on/reset only, so to set or change the VME interrupt vector, change the value
of I96, store this new value to non-volatile flash memory with the SAVE command, and reset the card
with the $$$ command. The active register into which the value of I96 is copied at power-on/reset is
X:$07000C bits 0 – 7. It is permissible to write to this register directly (suggested M-variable M96) to
change the active setup without a SAVE and reset.
I97 VME DPRAM Base Address Bits A23-A20
Range: $00 - $FF
Units: None
Default: $00
I97 controls bits A23 through A20 of the VME bus base address of the dual-ported RAM of Turbo
PMAC. Bit 3 of I93 corresponds to A20 of the base address, and bit 0 of I93 corresponds to A16. I97 is
only used if 24-bit or 32-bit addressing has been selected with I90 and I99.
Bits A19 through A14 of the DPRAM VME base address must be set by the host computer after every
power-on/reset by writing a byte over the bus to the “page select” register in the Turbo PMAC’s VME
mailbox IC at the mailbox base address + $0121. This must be done even with the single-page 8k x 16
standard DPRAM option. With the extended DPRAM option, the host computer must write to the page
select register every time a new page is accessed.
Actually I97 is used at power-on/reset only, so to set or change bits 8 to 15 of the VME bus DPRAM base
address, change the value of I97, store this new value to non-volatile flash memory with the SAVE
command, and reset the card with the $$$ command. The active register into which the value of I97 is
copied at power-on/reset is X:$07000D 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.
I98 VME DPRAM Enable
Range: $00 - $FF
Units: None
Default: $60
I98 controls whether VME access to the DPRAM IC on the Turbo 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.
Actually I98 is used at power-on/reset only, so to set or change the DPRAM enabling, change the value of
I98, 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 I98 is copied at power-on/reset is
X:$07000E 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.
I99 VME Address Width Control
Range: $00 - $FF
Units: None
Default: $10
I99 controls the VME bus address width, with or without DPRAM. It should take one of six values in
normal use: