Functional Description

BBRAM Interface

The PCCchip2 provides a read/write interface to the BBRAM by any bus master on the MC68040 bus. The PCCchip2 performs dynamic sizing for accesses to the 8-bit BBRAM to make it appear contiguous. This feature allows code to be executable from the BBRAM. The BBRAM device access time must be no greater than 5 BCLK periods in fast mode or 9 BCLK periods in slow mode. The BBRAM speed option is controlled by a control bit in the General Control Register.

3

82596CA LAN Controller Interface

The LAN controller interface is described in the following sections.

MPU Port and MPU Channel Attention

The PCCchip2 allows the (MC68040-compatible) Local Bus master to communicate directly with the Intel 82596CA LAN Coprocessor by providing a map decoder and required control and timing logic. Two types of direct access are feasible with the 82596CA: MPU Port and MPU Attention.

MPU Port access enables the MPU to write to an internal, 32-bit 82596CA command register. This allows the MPU to do four things:

1.Write an alternate System Configuration Pointer address.

2.Write an alternative dump area pointer and perform a dump.

3.Execute a software reset.

4.Execute a self-test.

Each Port access must consist of two 16-bit writes: Upper Command Word (two bytes) and Lower Command Word (two bytes). The Upper Command Word (two bytes) is mapped at $FFF46000 and the Lower Command Word (two bytes) is mapped at $FFF46002.

The PCCchip2 only supports (decodes) MPU Port writes. It does not decode MPU Port reads. (Nor does the 82596CA support MPU Port reads.)

http://www.motorola.com/computer/literature

3-3

Page 201
Image 201
Motorola MVME1X7P manual Bbram Interface, 82596CA LAN Controller Interface, MPU Port and MPU Channel Attention