Ip Clock Register - Motorola MVME162FX Programmer's Reference Manual

IP Clock Register

ADR/SIZ
BIT 7
NAME 0
OPER R
0 R
RESET
IP32
Note
$FFFBC01D (8 bits)
6 5
0 0
R R
0 R 0 R 0 R
Setting IP32 to a 1 enables the IndustryPack bus to
operate synchronously with the MC68040 local bus
clock, 32MHz (on MVME162-5xx boards only).
Setting it to a zero enables 8MHz operation (on both
MVME162-4xx and -5xx boards). In this mode, the
IndustryPack bus cycles and MC68040 local bus
cycles operate asynchronously.
The IP32 bit controls clock synchronization logic. It
does not change the clock frequency on the bus.
Jumper J24 on the MVME162FX printed circuit
board controls the IP bus clock source. If J24 pins 1
and 2 are jumpered, then the IP clock source is set to
8MHz. For this setting, the IP32 control bit must be a
0. If J24 pins 3 and 2 are jumpered, then the IP clock
source is set to be synchronous with a 32MHz
MC68040 local bus clock. For this setting, the IP32
control bit must be a 1. Whether the setting is 8MHz
or 32MHz, all IP ports operate at the same speed.
Some versions of the MVME162FX (those identified
with assembly number 01-W3960Bxxx) may have J24
factory-hardwired in the 8MHz position with a staple
between J24 pins 1 and 2, hidden beneath an IP module.
Changing the factory setting to the 32MHz setting
requires removal of the staple between pins 1 and 2,
and installation of a jumper between pins 2 and 3.
Programming Model
4 3 2
0 0 0
R R R
0 R 0 R
1 0
0 IP32
R S
0 R 0 R
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