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Dwangi
Registered: Dec 2001
Posts: 130 |
illegal opcodes that f
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... 13 posts hidden. Click here to view all posts....
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
@Steppe:
Thanx... Too bad it doesn't state the workings of the illegal opcodes.
For example: What does AHX do? Which flags are altered? And so on... |
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
Blueehhh...
Sorry I was too quick... IT DOES STATE IT ALL!!!
Thanx again |
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Monte Carlos
Registered: Jun 2004
Posts: 359 |
What does &H mean?
Monti Carlotti |
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
Ehr... I believe the H stands for the instruction pointer (program counter). This points to the instruction in mem which is beeing executed.
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
To extend this...
The H is short for PCH (according to some other docs on the net), where PC is program counter and the H is the Highbyte of the address...
So, if the PC would be $1234, PCH = $12 and PCL = $34. |
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Monte Carlos
Registered: Jun 2004
Posts: 359 |
so a
ldx #$05
ldy #$cc
shy $fe00
means
ldx #$05
lda #$cc
and #$ff ;h+1
sta $fe00,x
????
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
ehr... No...
The program counter points to the current opcode in memory which is beeing executed by the processor...
So...
*=$1000
PC:$1000 : lda #$01
PC:$1002 : ldy #$02
PC:$1004 : shy $2000
; then shy is:
; #$02 & #$20 and stores it in $2000 |
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
NO NO... TYPO!!!
*=$1000
PC:$1000 : lda #$01
PC:$1002 : ldy #$02
PC:$1004 : shy $2000
then shy is:
#$02 & #$10 and stores it in $2000
So #$10 and not #$20
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Nafcom
Registered: Apr 2002
Posts: 588 |
Quote: NO NO... TYPO!!!
*=$1000
PC:$1000 : lda #$01
PC:$1002 : ldy #$02
PC:$1004 : shy $2000
then shy is:
#$02 & #$10 and stores it in $2000
So #$10 and not #$20
HINT: CSDb has an edit function for posts if you are the last replyer in a thread! ;) |
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
Quote: HINT: CSDb has an edit function for posts if you are the last replyer in a thread! ;)
Ha cool...
I see... |
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