Computer Hardware User Manual

Table Of Contents
2-66 Computer Group Literature Center Web Site
VMEchip2
2
VME Access, Local Bus, and Watchdog Time-out Control Register
WDTO These bits define the watchdog time-out period:
LBTO These bits define the local bus time-out value. The timer
begins timing when TS is asserted on the local bus. If TA
or TAE is not asserted before the timer times out, a TEA
signal is sent to the local bus. The timer is disabled if the
transfer is bound for the VMEbus.
VATO These bits define the VMEbus access time-out value.
When a transaction is headed to the VMEbus and the
VMEchip2 is not the current VMEbus master, the access
timer begins timing. If the VMEchip2 has not received
bus mastership before the timer times out and the
transaction is not write posted, a TEA signal is sent to the
local bus. If the transaction is write posted, a write post
error interrupt is sent to the local bus interrupter.
ADR/SIZ $FFF4004C (8 bits of 32)
BIT 15 14 13 12 11 10 9 8
NAME VATO LBTO WDTO
OPER R/W R/W R/W
RESET 0 PS 0 PS 0 PS
Bit Encoding Time-out Bit Encoding Time-out
0512µs8128ms
1 1 ms 9 256 ms
2 2 ms 10 512 ms
34ms 111s
48ms 124s
5 16ms 13 16s
6 32ms 14 32s
7 64ms 15 64s
08 µs 2 256 µs
164 µs 3 The timer is disabled
064 µs232
ms
11 ms 3 The timer is disabled