Technical data

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Functional Description
4
Battery Backed Up RAM and Clock
An M48T58 RAM and clock chip is used on the MVME172LX. This chip
provides a time-of-day clock, oscillator, crystal, power fail detection,
memory write protection, 8KB of RAM, and a battery in one 28-pin
package. The clock provides seconds, minutes, hours, day, date, month,
and year in BCD 24-hour format. Corrections for 28-, 29- (leap year), and
30-day months are automatically made. No interrupts are generated by the
clock. Although the M48T58 is an 8-bit device, the interface provided by
the MC2chip supports 8-, 16-, and 32-bit accesses to the M48T58. Refer
to the MC2chip in the MVME172 VME Embedded Controller
Programmer’s Reference Guide and to the M48T58 data sheet for detailed
programming and battery life information.
VMEbus Interface and VMEchip2
The VMEchip2 ASIC provides the local-bus-to-VMEbus interface, the
VMEbus-to-local-bus interface, and the DMA controller functions of the
local VMEbus. The VMEchip2 also provides the VMEbus system
controller functions. Refer to the VMEchip2 description in the MVME172
VME Embedded Controller Programmer’s Reference Guide for detailed
programming information.
Note that the Abort switch logic in the VMEchip2 is not used. The GPI
inputs to the VMEchip2 which are located at $FFF40088 bits 7-0 are not
used. The Abort switch interrupt is integrated into the MC2chip ASIC at
location $FFF42043. The GPI inputs are integrated into the MC2chip
ASIC at location $FFF4202C bits 23-16.
I/O Interfaces
The MVME172LX provides onboard I/O for many system applications.
The I/O functions include serial ports and optional interfaces for IP
modules, LAN Ethernet transceivers, and SCSI mass storage devices.