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7d0dd140c3
Created a simple stylesheet, linked to it, and removed body color attributes defined there. This reduces repetition and separates style and presentation.
103 lines
2.3 KiB
HTML
103 lines
2.3 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
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"http://www.w3.org/TR/html4/loose.dtd">
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<HTML>
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<HEAD>
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<TITLE>xAsm Gameboy</TITLE>
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<link rel="stylesheet" type="text/css" href="../style.css">
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</HEAD>
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<BODY>
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<I><H2>Gameboy
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</H2></I>
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<HR>
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<P>The full GB-Z80 instruction-set is implemented with a few modifications to the original Zilog syntax. This is due
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to a Bison problem but in my opinion the syntax is better than the original one.<BR>
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<H4><BR>
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Instructions</H4>
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<PRE> ADC
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ADD
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AND
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BIT
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CALL
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CCF
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CP
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CPL
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DAA
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DEC
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DI
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EI
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EX
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HALT
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INC
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JP
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JR
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LD
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LDD
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LDI
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LDH/LDIO (see note below)
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NOP
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OR
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POP
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PUSH
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RES
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RET
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RETI
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RL
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RLA
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RLC
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RLCA
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RR
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RRA
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RRC
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RRCA
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RST
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SBC
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SCF
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SET
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SLA
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SRA
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SRL
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STOP
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SUB
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SWAP
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XOR</PRE>
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<P>Note that you can use both
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<PRE> OR A,B
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OR B</PRE>
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<H4><BR>Addressingmodes</H4>
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<P>Indirect addressing has been changed to [ ] instead of ( ):<BR>
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<PRE> A
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B
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C
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D
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E
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H
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L
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AF
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BC
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DE
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HL
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SP
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[BC]
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[DE]
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[HL]
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[HL-]/[HLI]
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[HL+]/[HLD]
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[SP]
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n8 (8 bit expression)
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n16 (16 bit expression)
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n3 (3 bit CONSTANT expression)
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[n16]/[$FF00+n8]
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[$FF00+C]/[C]</PRE>
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<P>The assembler will intelligently decide between <B>[n16]</B> and <B>[$FF00+n8]</B> in the LD instruction. Note however that if you use any <A HREF="symbols.htm">constant symbols</A> in the expression they had better be defined before the instruction or your symbol-table may become mangled. Also worth noting is that it will only ever select the short $FF00 mode when you use constant symbols. NOT if you use symbols defined in a <A HREF="section.htm">HRAM section</A>. As this defies the whole point of implementing the HRAM sectiontype I've added the LDIO mnemonic. It works like the LD instruction but it will ALWAYS generate the $FF00+ form and it will also automatically logically AND the expression with $FF if it is relocatable. Which is what you want. Trust me ;)<BR>
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<BR>
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<H4>Conditioncodes</H4>
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<PRE> C
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NC
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Z
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NZ</PRE>
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<BR><HR>
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<FONT SIZE="-1"><I><P ALIGN=RIGHT>Last updated 20 July 1997 by <A HREF="mailto:surfsmurf@matilde.demon.co.uk">Carsten Sorensen</A></P></I></FONT>
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