[comp.sys.apple] PEEK, POKE, paddle buttons

AWCTTYPA@UIAMVS.BITNET ("David A. Lyons") (04/12/89)

>Date:         Tue, 11 Apr 89 03:59:58 GMT
>From:         Brian Willoughby <microsoft!brianw@UUNET.UU.NET>
>Subject:      Re: Trouble with Applesoft's DEF FN
>
>In article <3038@m2-net.UUCP>, muaddib@m-net.UUCP (David Pieczkiewicz) writes:
>[...]
>> can be read by PEEK(49249), or PEEK(-16287) in the case of pre-IIe's, for
>> button #0 (AKA the Open-Apple key), and PEEK(49250) (PEEK(-16286) for
>[...]

PEEK and POKE can get at all 65536 locations in the 65x02's address
space.  The least confusing way to refer to these locations is using
the numbers 0 to 65535.

You can use negative numbers, too, to count down from the end of the
address space instead of counting up from the beginning.  -1 is the
same as 65535, -2 = 65534, -16287 = 49249, etc.  Just add and
subtract 65536 to convert between equivalent negative and positive
addresses.

There is no difference in the locations for reading joystick/etc
buttons between the older and newer Apple IIs.

 --David A. Lyons              bitnet: I'll let ya know
   DAL Systems                 CompuServe:   72177,3233
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