FCO DMB32-F001 (DAS), System/Process Page Table Entry Access Violations

This Field Change Order (FCO DMB32-F001) details an upgrade for the DMB32 (T1012) module, a VAXBI Communication Controller, to resolve a variety of system and communication issues. The FCO applies to systems exhibiting "System/Process Page Table Entry Access Violations," those using the LP29 (2000 LPM) printer, and any DMB32 modules showing other specified problems.

Key problems addressed include:

• Incorrect virtual-to-physical address translation leading to print queue hangs, system reboots, lost data, and "Line Sync Lost" errors.
• Poor throughput with the LP29 printer due to incompatible microcode.
• Intermittent diagnostic test failures and DMA errors causing system shutdowns.
• Asynchronous transmit and receive speed mismatches.
• Discarding of initial sync characters in GENBYTE or BISYNC modes.
• Issues with register updates at the termination of DMA transfers and BIIC EXT Vector Bit behavior.
• Physical addressing of Page Tables not implemented as per specifications.

The solution involves replacing the existing T1012 (DMB32) module with a new T1012-00 DMB32 module supplied in an EQ Kit. The rework instructions outline an orderly system shutdown, power disconnection, careful handling of electrostatic discharge sensitive components, and the physical replacement of the module. Post-installation, the diagnostic LED must confirm successful onboard diagnostics, and a standalone diagnostic (EVDAK) must be run, requiring a patch for EVDAK revision 3.0 to avoid false error reports. The estimated installation time is 1.0 hour. The FCO was released on June 18, 1989, with parts available in July 1989.