5-12
Computer Group Literature Center Web Site
Functional Description
5
Local Bus Timeout
The MVME167P provides a timeout function in the VMEchip2 ASIC for
the local bus. When the timer is enabled and a local bus access times out,
a Transfer Error Acknowledge (TEA) signal is sent to the local bus master.
The timeout value is selectable by software for 8
µ
sec, 64
µ
sec, 256
µ
sec,
or infinity. The local bus timer does not operate during VMEbus bound
cycles. VMEbus bound cycles are timed by the VMEbus access timer and
the VMEbus global timer.
Refer to the VMEchip2 description in the MVME1X7P Single Board
Computers Programmer’s Reference Guide for detailed programming
information.
Local Bus Arbiter
The local bus arbiter implements a fixed priority. The order of priority is
shown in
Connectors
The MVME167P has two 96-position DIN connectors: P1 and P2. P1 rows
A, B, C, and P2 row B provide the VMEbus interconnection. P2 rows A
and C provide the connection to the SCSI bus, serial ports, and Ethernet.
Pin assignments for the VME connectors on the MVME167P are listed in
Chapter 6, Connector Pin Assignments
Table 5-1. Local Bus Arbitration Priority
Device
Priority
Note
LAN
0
Highest
Serial I/O
1
SCSI
2
...
VMEbus
3
Next Lowest
MC68040 MPU
4
Lowest
