Specifications

CHAPTER 2
Hardware Design
10 Hardware Overview
As described in Chapter 1, there are two versions of the PC Compatibiity Card: the 12”
version and the 7” version. They perform the same functions; however, there are the
following differences between the cards:
■ The smaller 7” card is used in Macintosh systems where space is a critical factor.
■ The two cards have different microprocessors and chip sets.
■ The two cards implement onboard DRAM in different ways.
This chapter
■ provides a hardware overview of the cards
■ describes the functional blocks of circuitry, including the microprocessor, memory
system, video system, and I/O system
■ provides specifications for the monitors supported
Currently, both cards may be installed in the Power Macintosh 7200, 7500, 8500, and 9500
computers. The 7" card is also designed for installation in future systems that may have
mechanical size constraints.
Unless otherwise specified, the information provided in this chapter applies to both
cards.
Hardware Overview 2
Both cards are two-sided; that is, there are components on each side of the card. Figure
2-1 on page 11 shows outlines of both sides of the 12” card, with key ICs. Figure 2-2 on
page 12 shows equivalent views of the 7" card. Figure 2-3 on page 13 is a functional block
diagram of the 12” card. Figure 2-4 on page 14 is a functional block diagram of the
7" card.
The circuitry housed on the 12” and 7" cards includes the following:
■ The microprocessor or CPU.
the 12” card has a 100 MHz Pentium-class processor.
the 7" card has a 100 MHz 5x86-class processor.
■ The memory system, including the DRAM, cache memory, and memory expansion
module.
the 12” card has 8 MB of onboard DRAM. It also has a 168-pin DIMM slot. It allows
you to increase DRAM capacity by installing DIMMs with capacities up to 64 MB,
providing a total DRAM capacity of 72 MB. The card has a 256 KB cache.
the 7" card has 8 MB of onboard DRAM supplied by an 8 MB DIMM housed in the
card’s 168-pin DIMM slot. You can expand the 7" card’s DRAM capacity up to
64 MB by replacing the 8 MB DIMM with DIMMs of higher capacity. The card has a
128 KB cache.