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Turbo PMAC User Manual 
24 
Turbo PMAC System Configuration and Auto Configuration 
I4903 is also a collection of 16 independent bits, each reporting the type of MACRO IC at one of the 16 
possible locations.  A bit value of 1 indicates a DSPGATE2 IC; a bit value of 0 indicates a 
MACROGATE IC (or no IC present if the corresponding bit of I4900 is 0). 
While it is possible for up to 16 MACRO ICs to be installed in a Turbo PMAC system, only four of these 
can be supported at any time by automatic firmware functions.  I20 – I23 contain the base addresses of 
these four ICs.  When the system is re-initialized, these variables are set to values for the four ICs found 
with the lowest base addresses. 
DPRAM IC Configuration 
On power-up/reset, the Turbo PMAC CPU automatically tests for the presence of all possible dual-ported 
RAM ICs and reports the results in I4904.  I4904 is a collection of eight independent bits, each reporting 
the presence of a DPRAM IC at one of the eight possible locations.  Only one of these ICs can be 
supported at any time by automatic firmware functions.  I24 contains the base address of this IC. 
CPU Section Configuration 
On power-up/reset, the Turbo PMAC automatically tests for the configuration of its own CPU section and 
reports the results in I4908.  I4908 is a 36-bit value reporting the CPU type, active memory size, DPRAM 
size, battery-backed RAM size, flash memory size, presence of auxiliary serial port, part number, and 
vendor ID. 
UBUS Accessory Board Identification 
The Turbo PMAC can report detailed information about accessory boards installed on the UBUS 
expansion port in UMAC Turbo systems.  This information is reported in variable I4910 – I4965.  Each is 
a 36-bit variable with the following contents: 
Vendor ID: 8 bits 
Options present: 10 bits 
Revision number: 4 bits 
Card ID (part number): 14 bits 
Each variable can report one part or all parts of this information, depending on the setting of I39.  If I39 is 
set to 5, the variable reports the base address of the accessory board instead. 
I4910 – I4925 report this information for the 16 possible accessory boards with Servo ICs, such as the 
Acc-24E2, 24E2A, 24E2S, and 51E. 
I4926 – I4941 report this information for the 16 possible accessory boards with MACRO ICs, such as the 
Acc-5E. 
I4942 – I4949 report this information for the 8 possible accessory boards with DPRAM ICs, such as the 
Acc-54E USB/Ethernet interface. 
I4950 – I4965 report this information for the 16 possible accessory boards with I/O ICs, such as the Acc-
14E, 28E, 36E, 53E, and 59E.  (The Acc-9E, 10E, 11E, and 12E I/O boards currently cannot provide this 
information.) 
Setting System Clock Frequencies 
The phase clock and servo clock signals set the heartbeat for the entire Turbo PMAC system, 
synchronizing both hardware and software operations.  While the factory default frequencies – 9.04 kHz 
for the phase clock and 2.26 kHz for the servo clock – are suitable for most applications, some 
applications will either require changes, or could benefit from changes in one or both of these frequencies. 
The hardware tasks that are driven by the phase and servo clock signals include: 
• 
Latching of encoder counters 
• 
Latching of parallel feedback registers 
• 
Strobing of A/D converters and latching of resulting data 
• 
Output to D/A converters