head     1.1;
branch   1.1.1;
access   ;
symbols  start:1.1.1.1 Xerox:1.1.1;
locks    ; strict;
comment  @# @;


1.1
date     2001.08.12.22.22.22;  author freier;  state Exp;
branches 1.1.1.1;
next     ;

1.1.1.1
date     2001.08.12.22.22.22;  author freier;  state Exp;
branches ;
next     ;


desc
@@



1.1
log
@Initial revision
@
text
@{File name:  FloppyInitial.mc
Copyright (C) 1981, 1982, 1984, 1987 by Xerox Corporation.  All rights reserved. 
 Description: Initial microcode for the floppy disk booting sequence,
 Author: PXJ   ,
 Created: November 7, 1980,
 
last edited by: 
 
 RDH   22-Apr-87 10:21:35   Add last edit line to reflect MDS relief.
 Last Edited: AHL,  1-Feb-87 12:13:17 - MDS relieve. See comment at label GFT. (This line added by RDH to satisfy my need for order.).
 Last Edited: Dennis DEG     ,  1-Sep-84 22:05:14 - add copyright notice.
 Last Edited: ETN  , January 13, 1982  3:14 PM - deleted at miscRet
 Last Edited: PXJ   , March 23, 1981  10:46 AM}


SetTask[0],

DoneOnceOnlyInit:

{clear bank 0, 0-FFFF, takes 27 msec (411­-9 secs per click) (only the first two pages are of interest)}
	Noop, {miscRet used to be here. Not needed}	c1;
	rE¬ 0,	c2; {source of 0}
	rD¬ 0, rDrh¬ 0,	c3;

clearBank0:	MAR¬ [rDrh, rD+0],	c1;
	MDR¬ rE, rD¬ rD+1, ZeroBr,	c2;
	BRANCH[clearBank0, $],	c3;

{ The germ is in memory, but the map is wrong. The first page of the germ is its GFT. We move it from virtual page 1 to virtual page 200. Then shift virtual pages down by 1. The Remap loop stops at page FE, but I dont think the germ will ever get bigger. AHL }
	
GFT:	rBrh ¬ 1, rB ¬ 1,					c1;
	Noop,							c2;	
	rCrh ¬ 2, rC ¬ 0,					c3;
		
	MAR ¬ [rBrh, rB], { read page 1 map }			c1;
	rB ¬ 0FE, CANCELBR[$,2],				c2;
	rS ¬ MD, 						c3;
	
	Map ¬ [rCrh, rC], { page 200 ¬ old page 1 }		c1;
	MDR ¬ rS,  						c2;
	rS ¬ MD,						c3;


Remap:	MAR ¬ [rBrh, rB], { FE ¬ 200, FD ¬ FE, 1 ¬ 2 }		c1;
	MDR ¬ rS, rB ¬ rB - 1, CANCELBR[$,2], ZeroBr, WriteOK,	c2;
	rS ¬ MD, BRANCH[Remap, DoneRemap],			c3;
	
DoneRemap:	
{ end AHL }
	
	Noop,	c1;
	Noop,	c2;
	GOTO[exitToEmulator],	c3;
@


1.1.1.1
log
@first add
@
text
@@