Revision as of 01:27, 30 December 2018

Cortex-A8 (codename Tiger) is the successor to the ARM11, a low-power performance ARM microarchitecture designed by ARM Holdings for the mobile market. This microarchitecture is designed as an IP core and is sold to other semiconductor companies to be implemented in their own chips. The Cortex-A8 was designed by the Arm Austin design center.

Architecture

The Cortex-A8 was the first application processor from the Cortex family. It is also Arm's first superscalar, dual-issue microprocessor.

Key changes from ARM11

• 65 nm process (from 90 nm)
• ARMv7 (from ARMv6)
  • Support for NEON (ASIMD)
  • TrustZone
  • Thumb-2
  • Jazelle-RCT (Realtime Compilation Target)
• ARM reported 2.0 DMIPS/MHz (up from 1.2 DMIPS/MHz)
  • Average IPC reported is 0.9 (based on SPECint95, EEMBC, Mediabench, and others)
• First superscalar design
  • dual-issue (from single-issue)
  • in-order
  • 13-stage pipeline (up from 8 stages)
  • Targets frequency up to 1 GHz
• First NEON implementation
  • 10-stage pipeline
• Dedicated private L2 cache

Block Diagram

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Memory Hierarchy

• Cache
  • L1I Cache
    • 16 KiB OR 32 KiB (configurable)
  • L1D Cache
    • 16 KiB OR 32 KiB (configurable)
  • L2 Cache
    • 0 KiB OR 128 KiB OR 1 MiB (configurable)
    • Optional Parity and ECC

Die

• 65 nm process
• Up to 1 GHz
• 4 mm² (core only, no NEON, L2 cache, and embedded trace)
• <= 300 mW