Specifications

CPU Module 3-1
Chapter 3
CPU Module
The CPU module is a DECchip 21164 based dual-processor CPU module.
Each CPU chip has a dedicated 4-Mbyte module-level cache (B-cache) and
a shared interface to memory and I/O devices through the TLSB bus.
3.1 Major Components
The major components of the CPU module are:
• DECchip 21164 — One or two per module
• MMG — Address multiplexing gate array
• ADG — Address gate array
• DIGA — Data interface gate array
• B-cache — Backup cache
• Gbus — General purpose bus shared by both CPUs on a module
• DTag — Duplicate tag store
Figure 3-1 shows a simple block diagram of the CPU module.