[A83] Re: Official H**s Replacement Commands (OT)


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[A83] Re: Official H**s Replacement Commands (OT)




To clarify a bit, what he's saying is that >> 8 and & 255 are used to get the 8-bit pieces of a 16-bit address.  For example, when you do:
  ld hl,plotsscreen
What you're doing is equivalent to
  ld h,plotsscreen >> 8   ;upper byte
  ld l,plotsscreen & 255  ;lower byte

Thus you can use >> 8 and & 255 to just get one piece of the address if you don't want to do an entire 16-bit load.


In a message dated Tue, 3 Jul 2001  3:35:01 PM Eastern Daylight Time, "Kirk Meyer" <kirk.meyer@colorado.edu> writes:

<< 
>> 8 shifts right 8 (get upper byte)
& 255 ands with 255 (get lower byte)

In this code it's obviously a joke, but >> 8 is often used for optimizing
tables by splitting them across 256 bytes.

-----Original Message-----
From: assembly-83-bounce@lists.ticalc.org
[mailto:assembly-83-bounce@lists.ticalc.org]On Behalf Of Jeff Ruud
Sent: Tuesday, July 03, 2001 1:24 PM
To: assembly-83@lists.ticalc.org
Subject: [A83] Re: Official H**s Replacement Commands (OT)



What are the >> and & in those lines for?
    ld  a,plotsscreen >> 8
    ld  a,plotsscreen & 255


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