cyrix Application Note 120 III CPU BIOS Writer’s Guide free download

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Application Note 120 Cyrix III CPU BIOS Writer's Guide Cyrix Processors Running H/F 2 REVISION HISTORY Date Version Revision 11/24/99 1.1 Updated register 49h and DIR1 table 5/20/99 1.0 Updated for Cyrix III 4/19/99 0.43 Format changes, chapter 6. 3/22/99 0.42 Changed processor internal code name from MXs to Cyrix III. 3/17/99 0.41 Page 55: Added Core to Bus Clock Ratio Configuration Register. 2/23/99 0.4 Added Confidential Notice. Made all pages same width. 1/29/99 0.3 Minor changes: Changed fonts, added revision page, changed DIR table titles 12/14/98 0.2 Cyrix III information added. Completed Table page 32 9/21/98 0.1 Intial First Draft based on App Notes 112 and 118. C:\documentation\joshua\appnotes\j120ap.fm (confidential) 1 Cyrix Application Note 120 - Cyrix III BIOS Writer's Guide Running H/F 2 Table of Contents 1.0 Introduction 1.1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Cyrix Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.3 Summary of Cyrix III, MII, 6x86MX and 6x86 Differences . . . . . . . . . . . . . . . . . . . . 4 2.0 Cyrix III CPU Detection 2.1 CPU Detection and Inquiry Flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 CPU Detection Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.3 Standard and Extended CPUID Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.4 Non CPUID Test and Inquiry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 3.0 Cyrix III Configuration Register Index Assignments 3.1 Accessing a Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.2 Cyrix III Configuration Register Index Assignments . . . . . . . . . . . . . . . . . . . . . . . . 23 3.3 Configuration Control Registers (CCR0-6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 3.4 Address Region Registers (ARR0-7) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.5 Region Control Registers (RCR0-7) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.6