Description:

Intel 82385 32-bit Cache Controller for 80386

Note: there are 3 versions released at different times: 82385 20 MHz Version 1987-02-16 82385 25 MHz Version 1988-04-04 82385 33 MHz Version 1989-04-01

The 82385 Cache Controller is a high performance 32-bit peripheral for Intel's 80386 Microprocessor. It stores a copy of frequently accessed code and data from main memory in a zero wait state local cache memory. The 82385 enables the 80386 to run at its full potential by reducing the average number of CPU wait states to nearly zero. The dual bus architecture of the 82385 allows other masters to access system resources while the 80386 operates locally out of its cache. In this situation, the 82385's "bus watching" mechanism preserves cache coherency by monitoring the system bus address lines at no cost to system or local throughput.

The 82385 is completely software transparent, protecting the integrity of system software. High performance and board savings are achieved because the 82385 integrates a cache directory and all cache management logic on one chip.

• Improves 80386 System Performance
  • Reduces Average CPU Wait States to Nearly Zero
  • Zero Wait State Read Hit
  • Zero Wait State Posted Memory Writes
  • Allows Other Masters to Access the System Bus More Readily
• Hit Rates up to 99%
• Optimized as 80386 Companion
  • Simple 80386 Interface
  • Part of 386-Based Compute Engine Including 80387 Numerics Coprocessor and 82380 Integrated System Peripheral
  • 16 MHz, 20 MHz, and 25 MHz Operation
• Software Transparent
• Synchronous Dual Bus Architecture
  • Bus Watching Maintains Cache Coherency
• Maps Full 80386 Address Space (4 Gigabytes)
• Flexible Cache Mapping Policies
  • Direct Mapped or 2-Way Set Associative Cache Organization
  • Supports Non-Cacheable Memory Space
  • Unified Cache for Code and Data
• Integrates Cache Directory and Cache Management Logic
• High Speed CHMOS III Technology
• 132-Pin PGA Package