Nintendo 8 Bit Manual

 
 
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E.4 Indexed Absolute 
 
Indexed absolute addressing takes two operands, forming a 16-bit address, least significant 
byte first, and adds the value of a register to it to give the address where the data can be 
found. For example, if the operands are bb and cc, the address of the data will be ccbb + X. 
There are two forms of indexed absolute addressing: 
 
•  Absolute, X - Add contents of X register to operand. An example of this addressing mode 
is AND $1234.X. 
•  Absolute, Y - Add contents of...

 
 
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Figure E-5. Indirect addressing. 
 
E.6 Implied 
 
Many instructions do not require access to operands stored in memory. Examples of implied 
instructions are CLD (Clear Decimal Mode) and NOP (No Operation). 
 
E.7 Accumulator 
 
Some instructions operate directly on the contents of the accumulator. The only instructions 
to use this addressing mode are the shift instructions, ASL (Arithmetic Shift Left), LSR 
(Logical Shift Right), ROL (Rotate Left) and ROR (Rotate Right). 
 
E.8 Immediate...

 
 
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E.9 Relative 
 
Relative addressing is used in branch instructions. This addressing mode causes the value 
of the program counter to change if a certain condition is met. The condition is dependant on 
the instruction. The program counter increments by two regardless of the outcome of the 
condition but if the condition is true the single operand is added to the program counter to 
give the new value. For this purpose, the operand is interpreted as a signed byte, that is in 
the range -128 to 127...

 
 
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E.11 Indirect Indexed 
 
Indirect indexed (also known as post-indexed) addressing takes a single operand which 
gives the zero page address of the least significant byte of a 16-bit address which is then 
added to the Y register to give the target address. For example, if the operand is bb, 00bb is 
xx and 00bb + 1 is yy, then the data can be found at yyxx. An example of this addressing 
mode is AND ($12),Y. 
 
 
 
Figure E-19. Indirect indexed addressing. 
  

 
 
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Appendix F 
NES Colour Palette 
 
There are different interpretations of the NES colour palette. The palette as defined in [47] is 
shown below. Alternatives are presented in [5] and [48]. 
 
 
 
Figure F-1. NES colour palette. 
 
Palette 
Entry RGB Value  Palette 
Entry RGB Value 
00  75, 75, 75  20  FF, FF, FF 
01  27, 1B, 8F  21  3F, BF, FF 
02  00, 00, AB  22  5F, 97, FF 
03  47, 00, 9F  23  A7, 8B, FD 
04  8F, 00, 77  24  F7, 7B, FF 
05  AB, 00, 13  25  FF, 77, B7 
06  A7, 00, 00  26  FF, 77,...

 
 
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References 
 
[1]  Patrick Diskin, “Nintendo Entertainment System Emulator”, School of Computer 
Science, The University of Birmingham, 2004 
[2]  Andrew John Jacobs, “6502 Reference”, 
http://www.obelisk.demon.co.uk/6502/reference.html, 2002 
[3]  Andrew John Jacobs, “6502 Instructions”, 
http://www.obelisk.demon.co.uk/6502/instructions.html, 2002 
[4]  Andrew John Jacobs, “6502 Architecture”, 
http://www.obelisk.demon.co.uk/6502/architecture.html, 2002 
[5]  Chris Covell, “NES Technical /...

 
 
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[24]  RealityMan, “UltraHLE - Nintendo 64 High Level Emulator”, www.ultrahle.com, 2003 
[25]  Nintendo, “Legal Information (Copyrights, Emulators, ROMs, etc.)”, Nintendo of 
America Inc., http://www.nintendo.com/corp/legal.jsp 
[26]  The Scribe, “The Nintendo Emulation FAQ v2.0 - A Commentary”, EmulationZone, 
http://www.emulationzone.org/articles/emufaq/NFAQ20_response.zip, 1999 
[27]  Marcus Liedholm and Mattias Liedholm, “Nintendo Entertainment System (NES) or 
Famicom Tech specs and Hardware”,...