BVME4000/6000
34
Copyright
1993,1995,1998,2001 BVM Ltd.
7.7.4
Channel Attention Access
Reading from location
FF100000
causes a pulse on the 82596CA Channel Attention input. This
causes the 82596CA to execute command blocks.
7.7.5
Bus Error Handling
The 82596CA cannot directly handle bus errors. If the 82596CA is the bus master and accesses a
location from which a bus error is generated (e.g. accesses non-existent memory) then special
hardware on the BVME4000/6000 handles the error condition.
When a bus error occurs, the 82596CA is removed from the bus and kept off the bus by asserting
BOFF. ETHERR is generated causing an Ethernet Interrupt and the ETHERR bit to be set in the
Interrupt Local Status Register - refer to "7.8 Interrupt Controller (on page 35)" for details of interrupt
control and status. The 82596CA is held off the bus until a reset PORT command is issued to the
82596CA.
7.7.6
SYSBUS Byte Requirements
The SYSBUS byte of the SCP controls various hardware bus operations and must be set up as
follows:
Bit 6
Must be set.
INT
Bit 5
Must be clear (active high interrupt).
LOCK
Bit 4
LOCKed cycles are supported on the BVME4000/6000. It is recommended
that the LOCK function be enabled (bit is clear).
TRG
Bit 3
External Triggering is supported on the BVME4000/6000. It is recommended
that external triggering be used (bit is set).
M(1-0)
Bit 2,1 Should only be used in Linear Addressing Mode (bit 2 is set, bit 1 is clear).
7.7.7 Electrical
Interface
The BVME4000/6000 provides both a full 'Cheapernet' (IEEE802.3 - 10Base2) coaxial interface via the
front panel and an Attachment Unit Interface (AUI) port via P2. This allows a transition module to be
connected behind the backplane to provide connection to Thick Ethernet (IEE802.3 - 10Base5) or
other Ethernet standards (e.g. Twisted Pair IEE802.3 - 10BaseT) outside the BVME4000/6000
enclosure.
Selection between the on board Cheapernet interface or the P2 AUI connection is made by three links
- refer to "5.2.7 LK7,8,9 Ethernet AUI/Cheapernet Select (on page 15)" for details of the link settings.
An optional 10BaseT (twisted pair) module is available which replaces the Cheapernet connection.
The AUI port is not available when this module is fitted.
Содержание BVME4000
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