Merlin 8, general 6502 tips

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For Merlin 8

 Ctl-D = will skip outputting to the screen--
 LST OFF = ?


from main menu: (% prompt)

E = enter Editor and assembler
D = disk command
  disk commands:  prefix (to change directory)
                            brun printfiler (to capture assembly
output)


from Editor/assembler ( : prompt)
 user "asdf" = set filename (asdf) to save text as,
         after disk command: BRUN PRINTFILER has been entered
Q = go to main menu
A = start entering an assembly source file
E = go to editor

in editor:
control-Q = go to : prompt
control-X = start selection to cut, move cursor down to select more
lines
control-X again = cut out the selection
control-v = paste the "clipboard" to current cursor position

OP codes:

label1 DFB #00
label2 DFB #$00
label3 dfb #<label1 ;set label3 to the low byte of the address that
label 1 gets assembled to
label4 dfb #>label1 ;high byte of label1's address

label5 DS 40 ;define storage, 40 bytes

label6 asc "text" ;ascii data at address (label6), hibit set because
use quotes
label7 asc "text" ;ascii data at address (label7), hibit clear because
use apostrophes


self modifying code:

 lda #<code
 sta A1+1
 lda #>code
 sta A1+2

A1 JSR $2000  ;$2000 gets modified




self modifying code #2, like an "ON GOTO" statement in Applesoft
Basic.  based on Command, different routines are JSR'd (you could
change it to a JMP)

 ldy command

 lda AddressTableLows,y
 sta A1+1
 lda  lda AddressTableHighs,y
 sta A1+2

A1 JSR $2000  ;$2000 gets modified
 RTS

 lda AddressTableLows
 dfb #< command1
 dfb #< command2
 dfb #< command3
 dfb #< command4
 dfb #< command5

AddressTableHighs
 dfb #> command1
 dfb #> command2
 dfb #> command3
 dfb #> command4
 dfb #> command5


command1 dostuff
 lda
 beq
 wut
 evr
 rts

command2 dostuff
 lda
 beq
 wut
 evr
 rts

etc...