Motorola MVME162, Руководство пользователя

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Functional Description
4-2 User’s Manual
4
MC68040/MC68LC040 MPU
The MVME162 is equipped with an MC68040 or MC68LC040 microprocessor.
The MC68040/MC68LC040 have on-chip instruction and data caches; the
MC68040 also provides a floating-point coprocessor. Refer to the M68040
Microprocessor User’s Manual for more information.
EPROM and Flash Memory
The MVME162 implementation includes four 2-Mbit Flash devices organized
in a 256Kbit x 8 configuration. The EPROM location is a standard JEDEC 32-
pin PLCC capable of 4 Mbit densities (128 Kbit x 8; 256 Kbit X 8; 512 Kbit x 8;
1 Mbit x8) organized as a 512Kbit x 8 device. A jumper setting (GPIO3, pins 9-
10 on J22) allows reset code to be fetched either from Flash memory (GPIO3
installed) or from the EPROM (GPIO3 removed).
SRAM
The MVME162 provides 512KB of 32-bit-wide onboard static RAM in a single
non-interleaved architecture with onboard battery backup. The worst case
elapsed time for battery protection is 200 days. Specifics on SRAM
performance can be found in the section on the SRAM Memory Controller in
the MCchip Programming Model in the MVME162 Embedded Controller
Programmer’s Reference Guide. The SRAM arrays are not parity protected.
The battery backup function for the MVME162 SRAM is provided by a Dallas
DS1210S device that supports primary and secondary power sources. In the
event of a main board power failure, the DS1210S checks power sources and
switches to the source with the higher voltage.
If the voltage of the backup source is lower than two volts, the DS1210S blocks
the second memory cycle; this allows software to provide an early warning to
avoid data loss. Because the second access may be blocked during a power
failure, software should do at least two accesses before relying on the data.
The MVME162 provides jumpers (on J20) that allow either power source of the
DS1210S to be connected to the 5V STDBY pin or to one cell of the
onboard battery. For example, the primary system backup source may be a
battery connected to the 5V STDBY pin and the secondary source
may be the onboard battery. If the system source should fail or the board is
removed from the chassis, the onboard battery takes over.