3

MC2 Chip

Functional Description

The following sections provide an overview of the functions provided by the MC2 chip. A detailed programming model for the MC2 chip control and status registers is provided in a later section.

MC2 Chip Initialization

The MC2 chip ASIC is designed to accommodate several memory configurations and MVME172 population versions. Configuration registers are used to initialize the MVME172 Version Register, General Purpose Inputs Register, and DRAM/SRAM Options Register (read only).

Flash and PROM Interface

The MC2 chip interfaces the MC68060 local bus to one 2M X 8 Intel 28F016SA Flash device, and two 32-pin DIP JEDEC standard PROM sockets for the 200/300-Series modules and one PLCC socket for 400/500- Series modules. The Flash and PROM memory map locations can be swapped based upon a jumper (J11, pins 7 and 8, GPI3) input to the initialization PAL. (The initialization device was discussed in the previous section.) This enables the MVME172 to execute reset code from either the PROM or Flash.

The MC2 chip executes multiple cycles to the eight-bit Flash/PROM devices so that byte, word, or longword accesses are allowed. Burst accesses to Flash/PROM are inhibited by the interface so that they are broken into four longword accesses.

The MC2 chip ASIC supports write cycles to EPROM memory space with a normal cycle termination by asserting transfer acknowledge. Data is not changed. The MC2 chip allows the write cycle to time out.

The Flash memory has a write-protect feature. A CSR bit in the Flash Parameter Register (FWEN, bit 11) inhibits write cycles to Flash. Note that there is also a jumper which will inhibit writes to Flash. Refer to your MVME172 installation and use manual.

3-2

Computer Group Literature Center Web Site

Page 190
Image 190
Motorola MVME172 manual MC2 Chip Initialization, Flash and Prom Interface