22 Aug
2001
22 Aug
'01
12:03 a.m.
a long call or a jump takes 3 bytes, but we won't count that for now ...
.chip 6502
prport .def $FF00 ; send a character to this port and it transmits the
7 ascii bits. Use the MSB as strobe if your port doesn't generate a strobe for
you
.loc $0210
s: .ascii HELLO WORLD [11]
.byte $0D [1]
.loc $0200
ldx #11 ; length of this string (decimal) [2 bytes]
plp: lda s,x ; get the payload, byte by byte [1]
or #128 ; set the strobe [1]
sta prport ; and ship it [3 bytes]
and #127 ; now clear the strobe [1]
sta prport ; and write it again [3]
dex ; [1]
bne plp ; [2]
ret ; or whatever [1]
That's got to be about 27 bytes ... AND it uses no services or external storage
of any sort. Now, you could save a byte by mapping I/O into zero page ... and 4
if you don't have to generate a strobe, i.e. your port does that for you in
hardware, as many do. This is just a first guess ... it might be possible to
make it shorter.
Dick
----- Original Message -----
From: "Sean 'Captain Napalm' Conner" <spc(a)conman.org>
To: <classiccmp(a)classiccmp.org>
Sent: Tuesday, August 21, 2001 9:53 PM
Subject: Re: Hello World! on modern processors.
It was thus said that the Great Jay West once stated:
Yes, but per my earlier example.... are we shooting for less instructions in
the program or less intructions executed in total for the program? (ie, your
23 byte example is calling dos system services, so.... lots of additional
instructions there).
Well, this all started when Iggy said there wasn't a PRINT language
element in Assembly, so I suppose it's the easiest way to get something
printed, which means using built in system support.
Now, if you are doing this on an IBM PC the quickest way (assuming a CGA
card at minimum 8-) is possibly:
org 0100h
push cs
pop ds
mov ax,0b800h
mov es,ax
mov si,offset message
xor di,di
mov cx,12
rep movsw
ret
message db 'H',7,'e',7,'l',7,'l',7,'o',7,'
',7
db 'w',7,'o',7,'r',7,'l',7,'d',7,'!',7
end
-spc (42 bytes, more if you want to be pedantic and check for MDA ... )