Memory Maps

Notes 1. Devices mapped at $FFF80000-$FFF9FFFF also appear at $00000000- $001FFFFF when the ROM0 bit in the MC2 chip EPROM control register is high (ROM0=1). ROM0 is set to 1 after each reset. The ROM0 bit must be cleared before other resources (DRAM or SRAM) can be mapped in this range ($00000000 - $001FFFFF).

The EPROM/Flash memory map is also controlled by the EPROM size and by control bit V11 in the MC2 chip ASIC. Refer to the EPROM/Flash configuration tables in your MVME172 installation manual for further details.

2.This area is user-programmable. The DRAM and SRAM decoder is programmed in the MC2 chip, the local-to- VMEbus decoders are programmed in the VMEchip2, and the IP memory space is programmed in the IP2.

3.Size is approximate.

4.Cache inhibit depends on the devices in the area mapped.

5.The EPROM and Flash are dynamically sized by the MC2 chip ASIC from an 8-bit private bus to the 32-bit MPU local bus.

6.These areas are not decoded unless one of the programmable decoders is initialized to decode this space. If they are not decoded and the local timer is enabled, an access to this address range will generate a local bus time-out.

1

http://www.mcg.mot.com/literature

1-11

Page 29
Image 29
Motorola MVME172 manual Memory Maps