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MPM OPERATING SYSTEMS/MPM II/MPM II SOURCE/CONTROL/BOOT.ASM

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+;	MDS-800 Cold Start Loader for MP/M 2.0
+;
+;	VERSION 2.0    09/1481   
+;
+mpmldrb	equ	0100h	;base of MP/M loader
+;
+	org	3000h	;loaded here by hardware
+;
+ntrks	equ	2	;tracks to read
+mpmldr0	equ	25	;# on track 0
+mpmldr1	equ	26	;# on track 1
+;
+rmon80	equ	0ff0fh	;restart location for mon80
+base	equ	078h	;'base' used by controller
+rtype	equ	base+1	;result type
+rbyte	equ	base+3	;result byte
+reset	equ	base+7	;reset controller
+;
+dstat	equ	base	;disk status port
+ilow	equ	base+1	;low iopb address
+ihigh	equ	base+2	;high iopb address
+bsw	equ	0ffh	;boot switch
+readf	equ	4h	;disk read function
+stack	equ	100h	;use end of boot for stack
+;
+rstart:
+	lxi	sp,stack;in case of call to mon80
+;	clear disk status
+	in	rtype
+	in	rbyte
+;	check if boot switch is off
+coldstart:
+	in	bsw
+	ani	02h	;switch on?
+	jnz	coldstart
+;	clear the controller
+	out	reset	;logic cleared
+;
+;
+	mvi	b,ntrks	;number of tracks to read
+	lxi	h,iopb0
+;
+start:
+;
+;	read first/next track into cpmb
+	mov	a,l
+	out	ilow
+	mov	a,h
+	out	ihigh
+wait0:	in	dstat
+	ani	4
+	jz	wait0
+;
+;	check disk status
+	in	rtype
+	ani	11b
+	cpi	2
+;
+	jnc	rstart	;retry the load
+;
+	in	rbyte	;i/o complete, check status
+;	if not ready, then go to mon80
+	ral
+	cc	rmon80	;not ready bit set
+	rar		;restore
+	ani	11110b	;overrun/addr err/seek/crc/xxxx
+;
+	jnz	rstart	;retry the load
+;
+;
+	lxi	d,iopbl	;length of iopb
+	dad	d	;addressing next iopb
+	dcr	b	;count down tracks
+	jnz	start
+;
+;
+;	jmp to the MP/M loader
+	jmp	mpmldrb
+;
+;	parameter blocks
+iopb0:	db	80h	;iocw, no update
+	db	readf	;read function
+	db	mpmldr0	;# sectors to read trk 0
+	db	0	;track 0
+	db	2	;start with sector 2, trk 0
+	dw	mpmldrb	;start at base of bdos
+iopbl	equ	$-iopb0
+;
+iopb1:	db	80h
+	db	readf
+	db	mpmldr1	;sectors to read on track 1
+	db	1	;track 1
+	db	1	;sector 1
+	dw	mpmldrb+mpmldr0*128 ;base of second read
+	end
+