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1.1
date     2001.08.12.22.22.25;  author freier;  state Exp;
branches 1.1.1.1;
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1.1.1.1
date     2001.08.12.22.22.25;  author freier;  state Exp;
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-----------  Dandelion Processor Program - I/O Processor  -----------

  DESCRIPTION:      Module containing the entry point of the PreBoot diagnostics.

  Last modification by Roy RXO :   January 14, 1982  4:08 PM

  File: PreBootSimple.asm
  Stored:  [Iris]<WMicro>DLion>
  Written by Roy RXO .
  Dennis DEG     :  2-Sep-84 15:29:51, add copyright notice.
}

{ 	Copyright (C) 1982 by Xerox Corporation.  All rights reserved.}

;  Modification History:

;  Contains only the ReadAltBoot subroutine.
;	- Created (December 2, 1980  6:20 PM)
;	- Added DiagBootI, DiagBootN, LoopC init. (January 8, 1981  6:43 PM)
;	- Renamed to PreBootSimple. (June 17, 1981  1:31 PM)
;	- Modified ReadAltBoot for new AltBoot codes. (December 10, 1981  3:58 PM)
;	- Fixed AltBoot cycling so that 00 comes up first. (January 13, 1982  5:14 PM)
;	- Added Head cleaning AltBoot code. (January 13, 1982  5:14 PM)
;	- Moved ReadAltBoot to file AltBoot.asm. (January 14, 1982  2:33 PM)


;  DEFNITIONS:

	get "SysDefs"
	get "BootDefs"
	get "BootLinkDefs"

;  EXPORTS:
	EXP	PreBootGo	;  For RSTLinksK

;  IMPORTS: 
	IMP	ReadAltBoot	;  From AltBoot

{  This code contains the PreBoot code that is run before Phase 0.  Currently all that is in this
module is the dummy Entry point.}

;

;  Entry point of PreBoot diagnostics:
;  NOTE:  THis address is CALLed by the Boot code.
PreBootGo:
	jmp	PreBootStart

;  Check for presence of AltBoot and set BootType, DiagBoot
;  On return from ReadAltBoot:
;    A = 0 => normal AltBoot code
;    A # 0 => floppy head cleaning
PreBootStart:
	call	ReadAltBoot
	ora	a		;  Check type of AltBoot code
	jnz	DoFloppyHeadClean	;  nz => floppy head cleaning

;  Needed for Boot diagnostics.
InitDiag:
	mvi	a,1		;  Initialize diagnostic flags
	sta	DiagBootI
	mvi	a,3
	sta	DiagBootN
	xra	a
	sta	LoopC

;  Return to the Boot code:
	ret

;  Special AltBoot code to do floppy head cleaning.
;*** Currently unimplemented.
DoFloppyHeadClean:
	lxi	h,MPStartPhase0		;  Show a Phase 0 error
	shld	MPOffset
	mvi	c,ErrorInvalidBootType	;  ERROR:  Invalid BootType
	jmp	ErrorReportExt


	END	PreBootSimple
@


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