Reference Manual

PMAC 2 Software Reference
36 PMAC I-Variable Specifiation
The DPRAM locations used by PMAC for gathering are as follows;
Address Description
0x08FC
(Y:$D23F)
Data Gather Buffer Size.
0x08FC
(X:$D23F)
PMAC Data Gather Buffer Storage Address. If I45 = 2 and the
buffer’s end has been reached (this index is greater
than or equal to the size), the DEFINE GATHER
command must be issued again to allow gathering
to restart.
0x0900
($D240)
Start of Data Gather Buffer (not changeable).
Note:
In firmware version 1.16B and older, these addresses were 0x0100
($0040) lower.
See Also
Data Gathering (Analysis Features)
Option 2 Dual-Ported RAM
On-line commands DEFINE GATHER, GATHER, ENDGATHER, DELETE GATHER,
LIST GATHER
I46 CPU Frequency Control {PMAC w/Flex CPU only}
Range
0 .. 15
Units
Multiplication Factor
Default
0 (jumper-set frequency)
Remarks
I46 can control the operational clock frequency of the CPU in an Option 5xF “Flex” CPU
by controlling the multiplication factor of the phase-locked loop (PLL) inside the CPU.
The PLL circuit multiplies the input 10 MHz (actually 9.83 MHz) clock frequency by a
factor of (I46 + 1) to create the clock frequency for the CPU. Formally, this is expressed
in the equation:
CPU Frequency (MHz) = 10 * (I46 + 1)
If I46 is set to 0, or an older style of CPU (not “Flex”) is used, the CPU frequency is set by
jumpers (E48 on a PMAC(1); E2 and E4 on a PMAC2).
I46 should usually be set to create the highest CPU frequency for which the CPU is rated.
For the Option 5AF 40 MHz CPU, it should be set to 3; for the Option 5CF 80 MHz CPU,
it should be set to 7; for the Option 5EF 160 MHz CPU, it should be set to 15. With any of
the Flex CPU options (5xF), the PMAC will not permit the CPU to run at higher than the
rated frequency, and it will reduce I46 to the matching value..
I46 is actually used at power-on/reset only, so to make a change in the CPU frequency
with I46, change the value of I46, store this new value to non-volatile flash memory with
the SAVE command, and reset the card with the $$$ command.
I47 Address of Pointer for Control-W Command
Range
$0000 .. $FFFF (0 .. 65,535)
Units
Legal PMAC ‘Y’ addresses
Default
0
Remarks
I47 specifies the address of the register that tells the <CONTROL-W> command where to
pick up its command string.