mirror of
https://github.com/rzzzwilson/pymlac.git
synced 2025-06-10 09:32:41 +00:00
96 lines
2.6 KiB
NASM
96 lines
2.6 KiB
NASM
; 'c8lds' blockloader disassembled from chars.ptp.
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;
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; this loader is smart - it looks at the ROM code
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; and decides if it should use PTR or TTY.
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ORG 03700 ;
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cksum equ 03677 ; store checksum just below start address
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start RCF ; 03700 0001032
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JMP patch ; 03701 0013740 ; patch loadeer to use PTR or TTY
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rdblok DAC cksum ; 03702 0023677 ; AC is zero at this point
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skpzer JMS rdbyte ; 03703 0037760 ; wait for non-zero byte
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ASN ; 03704 0102001
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JMP skpzer ; 03705 0013703
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CIA ; 03706 0100006
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DAC wrdcnt ; 03707 0023777 ; save word count (or load address?)
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JMS rdword ; 03710 0037750 ; get load address
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DAC ldaddr ; 03711 0023776
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SAM eolval ; 03712 0077730
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JMP rddata ; 03713 0013715
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HLT ; 03714 0000000
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rddata JMS rdword ; 03715 0037750
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DAC *ldaddr ; 03716 0123776
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JMS updcks ; 03717 0037731
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ISZ ldaddr ; 03720 0033776
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ISZ wrdcnt ; 03721 0033777
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JMP rddata ; 03722 0013715
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JMS rdword ; 03723 0037750
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SUB cksum ; 03724 0073677
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ASN ; 03725 0102001
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JMP nxtblk ; 03726 0013746
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HLT ; 03727 0000000
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eolval DATA 0177777 ; 03730 0177777 ;' end-of-load' load address value
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;------------------------
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; Update checksum. New word in AC.
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; On exit, AC is updated checksum.
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;------------------------
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updcks DATA 0 ; 03731 0017720
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CLL ; 03732 0100010
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ADD cksum ; 03733 0067677
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LSZ ; 03734 0002004
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IAC ; 03735 0100004
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DAC cksum ; 03736 0023677
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JMP *updcks ; 03737 0113731
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;------------------------
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; Patch loader to use TTY or PTR.
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;------------------------
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patch HON ; 03740 0001061
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LAC pattty ; 03741 0063774
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DAC usetty ; 03742 0023761
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LAW 01032 ; 03743 0005032 ; load RCF instruction
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SAM *romflg ; 03744 0177775 ; skip if ROM is TTY (RCF @044)
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DAC usetty ; 03745 0023761 ; patch this code to use PTR
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nxtblk CAL ; 03746 0100011
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JMP rdblok ; 03747 0013702
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;------------------------
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; Read a word from the input device.
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;------------------------
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rdword DATA 0 ; 03750 0017711
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CAL ; 03751 0100011
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JMS rdbyte ; 03752 0037760
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RAL 3 ; 03753 0003003
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RAL 3 ; 03754 0003003
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RAL 2 ; 03755 0003002
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JMS rdbyte ; 03756 0037760
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JMP *rdword ; 03757 0113750
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;------------------------
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; Read a byte. Patched to use TTY or PTR.
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;------------------------
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rdbyte DATA 0 ; 03760 0017757
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usetty RCF ; 03761 0001032
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HSN ; 03762 0102400
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JMP .-1 ; 03763 0013762
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HSF ; 03764 0002400
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JMP .-1 ; 03765 0013764
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HRB ; 03766 0001051
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JMP *rdbyte ; 03767 0113760
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rdtty RSF ; 03770 0002040
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JMP .-1 ; 03771 0013770
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RRC ; 03772 0001033
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JMP *rdbyte ; 03773 0113760
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pattty JMP rdtty ; 03774 0013770
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romflg DATA 000044 ; 03775 0000044
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ldaddr DATA 000000 ; 03776 0000000
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wrdcnt DATA 000000 ; 03777 0000000
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END ;
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