'Production' c8lds blockloader

bin/blockloader_c8lds_ptr_tty.asm

@@ -0,0 +1,95 @@
+; 'c8lds' blockloader disassembled from chars.ptp.
+;
+; this loader is smart - it looks at the ROM code
+; and decides if it should use PTR or TTY.
+
+        ORG     03700   ;
+
+cksum   equ     03677   ; store checksum just below start address
+
+start	RCF		; 03700 0001032
+	JMP	patch	; 03701 0013740 ; patch loadeer to use PTR or TTY
+rdblok	DAC	cksum	; 03702 0023677 ; AC is zero at this point
+skpzer	JMS	rdbyte	; 03703 0037760 ; wait for non-zero byte
+	ASN		; 03704 0102001
+	JMP	skpzer	; 03705 0013703
+	CIA		; 03706 0100006
+	DAC	wrdcnt	; 03707 0023777 ; save word count (or load address?)
+	JMS	rdword	; 03710 0037750 ; get load address
+	DAC	ldaddr	; 03711 0023776
+	SAM	eolval	; 03712 0077730
+	JMP	rddata	; 03713 0013715
+	HLT		; 03714 0000000
+rddata	JMS	rdword	; 03715 0037750
+	DAC	*ldaddr	; 03716 0123776
+	JMS	updcks	; 03717 0037731
+	ISZ	ldaddr	; 03720 0033776
+	ISZ	wrdcnt	; 03721 0033777
+	JMP	rddata	; 03722 0013715
+	JMS	rdword	; 03723 0037750
+	SUB	cksum	; 03724 0073677
+	ASN		; 03725 0102001
+	JMP	nxtblk	; 03726 0013746
+	HLT		; 03727 0000000
+
+eolval	DATA	0177777	; 03730 0177777 ;' end-of-load' load address value
+
+;------------------------
+; Update checksum.  New word in AC.
+; On exit, AC is updated checksum.
+;------------------------
+updcks	DATA	0	; 03731 0017720
+	CLL		; 03732 0100010
+	ADD	cksum	; 03733 0067677
+	LSZ		; 03734 0002004
+	IAC		; 03735 0100004
+	DAC	cksum	; 03736 0023677
+	JMP	*updcks	; 03737 0113731
+
+;------------------------
+; Patch loader to use TTY or PTR.
+;------------------------
+patch	HON		; 03740 0001061
+	LAC	pattty	; 03741 0063774
+	DAC	usetty	; 03742 0023761
+	LAW	01032	; 03743 0005032 ; load RCF instruction
+	SAM	*romflg	; 03744 0177775 ; skip if ROM is TTY (RCF @044)
+	DAC	usetty	; 03745 0023761 ; patch this code to use PTR
+nxtblk	CAL		; 03746 0100011
+	JMP	rdblok	; 03747 0013702
+
+;------------------------
+; Read a word from the input device.
+;------------------------
+rdword	DATA	0	; 03750 0017711
+	CAL		; 03751 0100011
+	JMS	rdbyte	; 03752 0037760
+	RAL	3	; 03753 0003003
+	RAL	3	; 03754 0003003
+	RAL	2	; 03755 0003002
+	JMS	rdbyte	; 03756 0037760
+	JMP	*rdword	; 03757 0113750
+
+;------------------------
+; Read a byte.  Patched to use TTY or PTR.
+;------------------------
+rdbyte	DATA	0	; 03760 0017757
+usetty	RCF		; 03761 0001032
+	HSN		; 03762 0102400
+	JMP	.-1	; 03763 0013762
+	HSF		; 03764 0002400
+	JMP	.-1	; 03765 0013764
+	HRB		; 03766 0001051
+	JMP	*rdbyte	; 03767 0113760
+
+rdtty	RSF		; 03770 0002040
+	JMP	.-1	; 03771 0013770
+	RRC		; 03772 0001033
+	JMP	*rdbyte	; 03773 0113760
+
+pattty	JMP	rdtty	; 03774 0013770
+romflg	DATA	000044	; 03775 0000044
+ldaddr	DATA	000000	; 03776 0000000
+wrdcnt	DATA	000000	; 03777 0000000
+
+	END		;