Re: [stella] Climber5 source and binary

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Re: [stella] Climber5 source and binary

Subject: Re: [stella] Climber5 source and binary
From: "Andrew Davie" <atari2600@xxxxxxxxxxxxx>
Date: Fri, 18 Apr 2003 00:05:14 +1000

> And a potentional bug:
>    eor #$FE      ; make the number negative
> 
> This does only work for odd numbers!
>    1 eor $FE = $FF = -1
>    2 eor $FE = $FC = -4
>    3 eor $FE = $FD = -3

Two ways to make a number negative are...

    lda number
    eor #$FF
    clc
    adc #1

or

    sec
    lda #0
    sbc number

Cheers
A


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Current Thread
RE: [stella] Climber5 source and binary, (continued) Dennis Debro - Thu, 17 Apr 2003 06:10:21 -0400 (EDT) Thomas Jentzsch - Thu, 17 Apr 2003 09:59:28 -0400 (EDT) Eckhard Stolberg - Thu, 17 Apr 2003 17:12:16 -0400 (EDT) Dennis Debro - Thu, 17 Apr 2003 18:55:00 -0400 (EDT) Andrew Davie - Thu, 17 Apr 2003 10:00:47 -0400 (EDT) <= Andrew Davie - Thu, 17 Apr 2003 09:59:03 -0400 (EDT) Fabrizio Zavagli - Thu, 17 Apr 2003 15:56:16 -0400 (EDT) Dennis Debro - Thu, 17 Apr 2003 10:43:24 -0400 (EDT) Dennis Debro - Thu, 17 Apr 2003 10:59:47 -0400 (EDT)

Current Thread

RE: [stella] Climber5 source and binary, (continued)
- Andrew Davie - Thu, 17 Apr 2003 09:59:03 -0400 (EDT)
- Fabrizio Zavagli - Thu, 17 Apr 2003 15:56:16 -0400 (EDT)
- Dennis Debro - Thu, 17 Apr 2003 10:43:24 -0400 (EDT)
- Dennis Debro - Thu, 17 Apr 2003 10:59:47 -0400 (EDT)

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