Motorola MVME172 ユーザーズマニュアル

4-2

Computer Group Literature Center Web Site

IP2 Chip

The following sections provide an overview of the functions provided by 
the IP2 chip. A detailed programming model for the IP2 chip control and 
status registers is provided in a later section of this chapter. 

The IP2 chip converts IP-bound MC68060 read/write/interrupt 
acknowledge cycles to IndustryPack cycles. Control registers within the 
IP2 chip control the assumed width of the IndustryPack that is being 
accessed. The IP2 chip interfaces to four 16-bit IndustryPack positions. 
The naming convention for single size IndustryPack population of each of 
these positions is: IndustryPack-a (IP_a), IndustryPack-b (IP_b), 
IndustryPack-c (IP_c), and IndustryPack-d (IP_d). The naming convention 
for double size IndustryPack population of these positions is IndustryPack-
a/b (IP_ab) and IndustryPack-c/d (IP_cd). (A double size IndustryPack can 
occupy positions A and B, or it can occupy positions C and D.) 

The 200/300-Series MVME172 does not implement 
interfaces to IP_c and IP_d, although these interfaces are 
documented in Chapter 4 and the physical control registers 
for them exist.

The IP2 chip observes the snoop control (SC0) and memory inhibit (MI*) 
signals to maintain cache coherency. When SC0 indicates that snooping is 
inhibited, the IP2 chip pair ignores the memory inhibit (MI*) signal line. 
When SC0 does not indicate that snooping is inhibited, the IP2 chip waits 
for the negation of MI* before responding to a cycle. If TA* or TEA* is 
asserted by another local bus slave before MI* is negated, then the IP2 chip 
assumes that the cycle is over and that it is not to participate.