home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
The Atari Compendium
/
The Atari Compendium (Toad Computers) (1994).iso
/
files
/
umich
/
falcon
/
programm.ing
/
asm56.zoo
/
disp.a56
< prev
next >
Wrap
Text File
|
1992-11-14
|
936b
|
44 lines
;
; disp: display the character in the high byte of A1 on the readout
;
disp
move #~($F<<7),x0 a,y1 ;save a, x0=mask
;
; copy in the low nibble
;
movep x:m_pbd,a1 ;get b port contents
and x0,a #$F<<7,x1 ;clear display nibble, x1=mask
move y1,b ;get char
rep #16-7 ;shift it down
lsr b
and x1,b ;mask nibble
move b1,y0 ;and or it into b port
or y0,a
movep a1,x:m_pbd ;and write back b port
;
; write out to the display
;
bclr #11,x:<<m_pbd ;strobe (setup=25, hold=25, pw=50)
bset #11,x:<<m_pbd ;and negate
;
; copy in the high nibble
;
and x0,a ;a has port b, clear nibble again
move y1,b ;get char
rep #16-7+4 ;shift down the high nibble
lsr b
and x1,b ;mask the nibble
move b1,y0 ;and or into b data
or y0,a
movep a1,x:m_pbd ;write back to port
;
; write out to the display
;
bclr #12,x:<<m_pbd ;assert the strobe
bset #12,x:<<m_pbd ;and negate
;
; restore a and return
;
move y1,a
rts