User`s manual

1.2 Board Components and Features

1.2.2 DECchip 21072 Support Chipset

The 21064A is supported by a DECchip 21072 ASIC chipset (21072), with a

128-bit memory interface. The chipset consists of the following three chips:

• DECchip 21071-CA (21071-CA) provides the interface from the CPU to

cache and main memory, and includes the cache and memory controller.

• DECchip 21071-BA (21071-BA) provides a 32-bit data path from the CPU

to memory and I/O. Four chips provide the 128-bit interface.

• DECchip 21071-DA (21071-DA) provides an interface from the CPU to the

peripheral component interconnect (PCI) bus.

The chipset includes the majority of functions required for a high-performance

PC or workstation, requiring minimum discrete logic on the Alpha PCI 64–275.

The chipset provides ﬂexible and generic functions to allow its use in a wide

range of applications.

For more information on the DECchip 21072 chipset, see the DECchip 21071

and DECchip 21072 Core Logic Chipsets Data Sheet.

1.2.3 PAL Control Set

The Alpha PCI 64–275 contains a 4-PAL control set and includes the following:

• Two 16V8-5 PALs provide L2 cache output-enable and write-enable

functions.

• One 22V10-25 PAL provides interrupt address decode functions and utility

bus (Ubus) control.

• One MACH210-20 PAL provides the PCI and ISA interrupts.

1.2.4 Level 2 Cache Subsystem Overview

Alpha PCI 64–275 motherboards are sold with the external level 2 (L2) cache

subsystem conﬁgured with 2MB cache memory using two 1MB dual inline

memory modules (DIMMs) with an access time of 12ns. You can increase

or decrease the L2 cache size by replacing the DIMMs with other sizes and

changing onboard hardware and software jumpers. Your application’s cache

hit rate may improve with faster or more cache. Contact your Digital Field

Application Engineer (FAE) or your local sales representative for assistance.

1–4 Alpha PCI 64–275 Introduction