Int 15/AH=C8h

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SYSTEM - ENABLE/DISABLE PROCESSOR FUNCTIONS

AH = C8h
AL = function
00h disable L1 cache
01h enable L1 cache
---models 90 and 95 only---
02h disable L2 cache
03h enable L2 cache
04h disable both caches
05h enable both caches
06h return status of both caches
07h-FFh Reserved

Return:
CF set on error CF clear if successful AH = status (see #00527) For subfunction 06h only: BL = status of L1 cache 00h enabled 01h disabled or not installed 02h disabled due to test error (can not be enabled) BH = status of L2 cache (same codes as BL)

Notes: Supported by at least PS/2 70, 70/486, 80-A21, 90, 95. Call AH=C0h and examine bit 3 of feature byte 2 to check if this function is supported.. On a 486 system, any external caches must be disabled when the on-chip cache (L1) is disabled.

See Also: AH=C0h

(Table 00527) Values for status: 00h operation successful 01h function choice (in AL) is invalid 02h NVRAM data is invalid 03h cache test error 04h (90 and 95 only) cannot perform operation requested due to state of other cache (also see note above) 05h no L2 cache is present 07h invalid input values 09h CPU in protected mode

Category: Bios - Int 15h - S

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