Reference Manual

Flex CPU Piggyback Board Hardware Reference
8 Operation of the Flex CPU
I54 Baud Rate I54 Baud Rate
0 600 8 9600
1 900 9 14,400
2 1200 10 19,200
3 1800 11 28,800
4 2400 12 38,400
5 3600 13 57,600
6 4800 14 76,800
7 7200 15 115,200
Note that these values can be different from those used on PMAC2 boards with jumper-set CPU
frequencies (see below).
• If the saved value of I46 is 0, so the CPU’s operational frequency is determined by jumper settings,
then the serial baud rate is determined by a combination of the setting of jumpers E44-E47 and the
CPU frequency on a PMAC(1) board, as shown in the following table. These settings maintain
backward compatibility.
E44 E45 E46 E47 Baud Rate
for
20MHz
Baud Rate
for
40MHz
Baud Rate
for
60MHz
N ON ON ON Disabled Disabled Disabled
OFF ON ON ON 300 600 900
ON OFF ON ON 400* 800* 1200
OFF OFF ON ON 600 1200 1800
ON ON OFF ON 800* 1600* 2400
OFF ON OFF ON 1200 2400 3600
ON OFF OFF ON 1600* 3200* 4800
OFF OFF OFF ON 2400 4800 7200
ON ON ON OFF 3200* 6400* 9600
OFF ON ON OFF 4800 9600 14400
ON OFF ON OFF 6400* 12800* 19200
OFF OFF ON OFF 9600 19200 28800
ON ON OFF OFF 12800* 25600* 38400
OFF ON OFF OFF 19200 38400 57600
ON OFF OFF OFF 25600* 51200* 76800
OFF OFF OFF OFF 38400 76800 115200
* Not an exact baud rate