Re: A83: Re: Newbies :)

To: assembly-83@lists.ticalc.org
Subject: Re: A83: Re: Newbies :)
From: "Evil Sam" <evil_sam@hotmail.com>
Date: Sat, 05 Dec 1998 19:42:55 PST
Delivered-To: assembly-83-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-83@lists.ticalc.org


>Here's the bit of code from Joe's PW program that turns the calc off... 
Do
>with it what you will, and direct questions to him... =P
>															--Jason K.
>	di				; turn off interrupts
>	ld	a, $01		;\
>	out	(3), a		;  \ Tell the calculator to shut down
>	xor	a			;  / at getkey
>	out	(4), a		;/
>	ei				; turn the interrupts back on
>	res	4, (iy+9)	; get rid of the "on" flag to prevent errors
>	call getkey		; shut down the calculator and wait for [ON]
>
>	; Note By Me:  His "getkey" is the equivalent of "_getkey".

 "xor a / out (4),a" will screw up the calc's interrupt speed. The 
correct shutdown code is this(taken from Penguins 82/83, Bill Nagel 
can't be wrong :). The getkey part is unnecessary. If the ON flag is 
cleared, then it will wait for the ON flag to occur :)

OFF:
  RES 4, (IY $09)     ; Turn off 'ON' flag
  DI                  ; disable interrupts
  LD  A, 01           ; bit 3 = lcd status
  OUT ($03), A        ; bit 0 = ON-interrupt status
  XOR A               ; make interrupts go fast
  OUT ($04), A
  EI                  ; enable interrupts
  HALT                ; wait for ON (that's the only interrupt)
  DI
  LD  A, $16          ; Default setting for interrupt speed
  OUT ($04), A
  ret



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