Hi freaks, this is VECTOR again with a mega mighty small article.


First I want to tell you how I hate that $DFF09A etc mess things...
Why not use INTENA(a6)   (with $DFF000 in a6)
This is :   1 :Faster !!!
            2 :Cleaner !?
            3 :Easier to understand for (beginning/advanced) coders.

You could of course type the equ's from INTERN.
But the complete list is on NF9.
(Together with my article about trackloading)



Second: Here is a little routine to calculate you bootblock checksum.
        Handy when writting your own bootblock (virus!?!)


CalcChk	lea	BootBlock,a0	;begin address of bootblock
	clr.l	4(a0)		;clear old checksum
	move.w	#1024/4-1,d7	;a few longwords
	moveq	#-1,d0		;start value

Loop	move.l	(a0)+,d1	;get next longword
	subx.l	d1,d0
	dbf	d7,Loop

	move.l	d0,-1020(a0)	;store checksum



Third: If you want to add a number to an address register, you could
       do the following:

	ADDA.W	#64*384,A0

       But FASTER is:

	LEA	64*384(A0),A0

Only ADDQ.W is as fast as this instruction.

Note that    LEA 0(A0,D0.W),A0    NOT faster is than   ADD.W D0,a0
(Wrong addressing mode !!)


If you have any questions about coding (machine code), previous articles,
this article, ideas for utilities/demos then contact me. 

My address is :   P. de Boer
                  Zeeloodsenlaan 79
                  1785 BM  Den Helder
                  Holland

or Call between 15:00-20:00  (dutch time !!):

                  (0)2230-31657 (Ask for Patrick)



Sorry, that this is article is so small, but I had not enough time to
write more. In next months article I will tell you about a really fast
scroll routine. (Faster than the scroll routine that SLASH uses, and his
was fast.)

Well see you next month (Or not ??)