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Functional Description
MC68040 MPU
The MC68040 processor is used on the MVME167. The MC68040 has on-chip
instruction and data caches and a floating point processor. Refer to the MC68040 user's
manual for more information.
EPROM
4
There are four 44-pin PLCC/CLCC EPROM sockets for 27C102JK or 27C202JK type
EPROMs. They are organized as two 32-bit wide banks that support 8-, 16-, and 32-bit
read accesses. The EPROMs are mapped to local bus address 0 following a local bus
reset. This allows the MC68040 to access the stack pointer and execution address
following a reset. The EPROMs are controlled by the VMEchip2. The map decoder,
access time, and when they appear at address 0 is programmable. For more detail, refer
to the VMEchip2 in the MVME166/MVME167/MVME187 Single Board Computers
Programmer's Reference Guide.
SRAM
The boards include 128KB of 32-bit wide static RAM that supports 8-, 16-, and 32-bit
wide accesses. The SRAM allows the debugger to operate and limited diagnostics to
be executed without the DRAM mezzanine. The SRAM is controlled by the
VMEchip2, and the access time is programmable. Refer to the VMEchip2 in the
MVME166/MVME167/MVME187 Single Board Computers Programmer's Reference
Guide for more detail. The boards are populated with 100 ns SRAMs.
SRAM battery backup is optionally available on the MVME167. The battery backup
function is provided by a Dallas DS1210S. Only one backup power source is supported
on the MVME167.
Each time the MVME167 is powered, the DS1210S checks power source and if the
voltage of the backup source is less than two volts, the second memory cycle is
blocked. This allows software to provide an early warning to avoid data loss. Because
the DS1210S may block the second access, the software should do at least two accesses
before relying on the data.
Optionally, the MVME167 provides jumpers that allow the power source of the
DS1210S to be connected to the VMEbus +5 V STDBY pin or the onboard battery.
The optional power source SRAM is a socketed Sanyo CR2430 battery. A small
capacitor is provided to allow the battery to be quickly replaced without data loss.
The lifetime of the battery is very dependent on the ambient temperature of the board
and the power-on duty cycle. The FB1225 and CR2430 lithium batteries should
provide at least two years of backup time with the board powered off and the board at
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MVME167 Single Board Computer User's Manual
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