Table of Contents
Advertisement
I
HARDWARE PREPARATION
2.3.1 VMEbus Lock For VSBbus
(J
1)
Jumper block JI allows the RMC* (Read Modify Cycle) signal from the
MC68020 processor to be asserted on the reserved bus pin P2-B3. This
option is provided for users that require access locking of the
slave ports that may have a dual bus interface. Normal bus locking
occurs on VMEbus without this jumper for single ported VMEbus slave
modules.
Since this lock feature is not part of the VMEbus
specification and since it utilizes a reserved bus pin, use of this
feature is recommended only when no other method will suffice.
Therefore, JI is normally not installed.
VMEmodules MVME204-x and MVME214 have a similar jumper option to
allow their use with the lock feature described above. This jumper
does not need to be installed if the system software executes only
TAS (Test And Set) RMC instruction cycles.
Jumper Block JI
VMEbus Lock (Disabled)
No Jumper Installed
(Factory Setting)
==========================
: Fl
2.3.2 Bus Grant/Request Level Select
(J2)
Jumper Block JI
VMEbus Lock (Enabled)
Jumper Installed
The VMEbus has four prioritized bus request levels (BR0* through
BR3*), each having an associated bus grant daisy-chain. Level 3 has
the highest priority while level 0 has the lowest. Jumper block J2
allows the user to select the desired priority level for VMEbus
accesses.
The following configurations illustrate the proper jumpering for
each bus arbitration 1 evel .
If
the MVMEl35/136 is the system
controller, then the level 3 configuration is recommended.
NOTE:
No other configurations will work properly.
2-4
Advertisement
Table of Contents
