mirror of
https://github.com/rzzzwilson/pymlac.git
synced 2025-06-10 09:32:41 +00:00
83 lines
2.6 KiB
NASM
83 lines
2.6 KiB
NASM
;-----------------------
|
|
; 'lc16sd' blockloader code
|
|
; disassembled from munch.ptp
|
|
;-----------------------
|
|
org 03700 ; addr code
|
|
|
|
ldaddr rcf ; 03700 0001032
|
|
numwrd jms . ; 03701 0037701 get address of 'chksum' into 'numwrd'
|
|
|
|
chksum lac numwrd ; 03702 0063701 are we are running in high memory (017700+)
|
|
sam himem ; 03703 0077775
|
|
jmp rdblk ; 03704 0013710 if not, just load tape
|
|
|
|
lwc 012 ; 03705 0104012 else turn on the display
|
|
dla ; 03706 0001003
|
|
don ; 03707 0003100
|
|
|
|
rdblk cal ; 03710 0100011 initialize block checksum
|
|
dac chksum ; 03711 0023702
|
|
jms rdword ; 03712 0037746 get load address
|
|
dac ldaddr ; 03713 0023700
|
|
asp ; 03714 0002002 if high bit set
|
|
jmp ldend ; 03715 0013740 then end of tape load
|
|
jms rdword ; 03716 0037746 else get number of words in block
|
|
dac numwrd ; 03717 0023701
|
|
jms rdword ; 03720 0037746 read checksum word, add to checksum
|
|
blklp jms rdword ; 03721 0037746 get data word
|
|
dac *ldaddr ; 03722 0123700 store into memory
|
|
lac ldaddr ; 03723 0063700 get load address
|
|
sar 3 ; 03724 0003063 echo load address in display (if running)
|
|
and low10 ; 03725 0047765
|
|
ior dlya0 ; 03726 0053764
|
|
dac disp ; 03727 0023766
|
|
lac *ldaddr ; 03730 0163700 get last data word
|
|
isz ldaddr ; 03731 0033700 move 'load address' pointer
|
|
isz numwrd ; 03732 0033701 check end of block
|
|
jmp blklp ; 03733 0013721 jump if not ended
|
|
add chksum ; 03734 0067702 block end, check checksum
|
|
asz ; 03735 0002001 if checksum invalid,
|
|
jmp . ; 03736 0013736 busy wait here
|
|
jmp rdblk ; 03737 0013710 else go get next block
|
|
; end of load, AC is load address, high bit set
|
|
ldend dof ; 03740 0001012 turn off the display
|
|
iac ; 03741 0100004
|
|
asn ; 03742 0102001 if address is 0177777
|
|
hlt ; 03743 0000000 then just halt
|
|
jms rdword ; 03744 0037746 else get AC contents
|
|
jmp *ldaddr ; 03745 0113700 and jump to start address
|
|
; read a word from tape, leave in AC
|
|
rdword bss 1 ; 03746 0000000
|
|
add chksum ; 03747 0067702
|
|
dac chksum ; 03750 0023702
|
|
cal ; 03751 0100011
|
|
rsf ; 03752 0002040
|
|
jmp .-1 ; 03753 0013752
|
|
rrc ; 03754 0001033
|
|
ral 3 ; 03755 0003003
|
|
ral 3 ; 03756 0003003
|
|
ral 2 ; 03757 0003002
|
|
rsf ; 03760 0002040
|
|
jmp .-1 ; 03761 0013760
|
|
rrc ; 03762 0001033
|
|
jmp *rdword ; 03763 0113746
|
|
|
|
dlya0 dlya 0 ; 03764 0020000
|
|
low10 data 001777 ; 03765 0001777
|
|
|
|
; display routine, used if running in extended memory
|
|
disp dlya 00000 ; 03766 0020000
|
|
dlxa 00000 ; 03767 0010000
|
|
dsts 1 ; 03770 0004005
|
|
data 0046000 ;DLVH 02000 ; 03771 0046000
|
|
dlya 01777 ; 03772 0021777
|
|
dhlt ; 03773 0000000
|
|
|
|
data 0067766 ; 03774 0067766
|
|
himem data 0017702 ; 03775 0017702
|
|
data 0010000 ; 03776 0010000
|
|
data 0177777 ; 03777 0177777
|
|
data 0000000 ; 04000 0000000
|
|
|
|
end ;
|