Ip Clock Register - Motorola MVME172 Programmer's Reference Manual

IP2 Chip

IP Clock Register

ADR/SIZ
BIT
NAME
4
OPER
RESET
4-28
7 6
0 0
R R
0 R 0 R 0 R
IP32 Setting IP32 to a one enables the IndustryPack bus to
operate synchronously with the MC68060 local bus clock.
Setting it to a zero will enable 8 MHz operation. In this
mode, the IndustryPack bus cycles and MC68060 local
bus cycles operate asynchronously.
The IP32 bit controls clock synchronization logic. It does
not change the clock frequency on the bus. Jumper J11 on
the 200/300-Series MVME172, and Jumper J14 on the
400-/500-Series, control the IP bus clock source. If J11
(200/300-Series) or J14 (400/500-Series) pins 1 and 2 are
jumpered, then the IP clock source is set to 8 MHz. For
this setting, IP32 control bit must be a zero.
If pins 3 and 2 are jumpered, then the IP clock source is
set to be synchronous with the MC68060 local bus clock.
This clock may be 25 MHz, 30 MHz, or 32 MHz
depending on the model. For this setting, IP32 control bit
must be a one.
Note
For some early versions of the 200/300-Series MVME172,
J11 is factory hardwired to the 8 MHz position (pins 1 and 2
connected). If the 32 MHz option is desired, remove the
staple between pins 1and 2 and install a jumper between pins
2 and 3. The person performing this work must ensure that
the MVME172 is ESD (Electro Static Discharge) protected.
$FFFBC01D (8 bits)
5 4 3
0 0 0
R R R
0 R 0 R
Computer Group Literature Center Web Site
2 1 0
0 0 IP32
R R S
0 R 0 R 0 R