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5 <title>Nintendo Entertainment System specific information for cc65
6 <author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
7 Stefan A. Haubenthal, <htmlurl url="mailto:polluks@sdf.lonestar.org" name="polluks@sdf.lonestar.org">
11 An overview over the NES runtime system as it is implemented for the
15 <!-- Table of contents -->
18 <!-- Begin the document -->
22 This file contains an overview of the NES runtime system as it comes
23 with the cc65 C compiler. It describes the memory layout, NES specific header
24 files, available drivers, and any pitfalls specific to that platform.
26 Please note that NES specific functions are just mentioned here, they are
27 described in detail in the separate <htmlurl url="funcref.html" name="function
28 reference">. Even functions marked as "platform dependent" may be available on
29 more than one platform. Please see the function reference for more
33 <sect>Binary format<p>
35 The standard binary output format generated by the linker for the NES target
36 is a machine language program with an INES cartridge header. It is of course
37 possible to change this behaviour by using a modified startup file and linker
40 <sect>Memory layout<p>
42 cc65 generated programs with the default setup run with the I/O area and a
43 CHR bank enabled, which gives a usable memory range of $8000 - $FFF3.
44 All boot ROM entry points may be called directly without additional code.
50 The text screen is located at VRAM $2000.
53 The C runtime stack is located at $7FFF and growing downwards.
56 The C heap is located at the end of the program and grows towards the C
63 <sect>Platform specific header files<p>
65 Programs containing NES specific code may use the <tt/nes.h/ header file.
68 <sect1>NES specific functions<p>
77 <sect1>Hardware access<p>
79 The following pseudo variables declared in the <tt/nes.inc/ include file do
80 allow access to hardware located in the address space.
85 The <tt/PPU/ defines allow access to the PPU chip.
88 The <tt/APU/ defines allow access to the APU chip.
94 <sect>Loadable drivers<p>
96 All drivers must be statically linked because no file I/O is available.
97 The names in the parentheses denote the symbols to be used for static linking of the drivers.
100 <sect1>Graphics drivers<p>
104 <tag><tt/nes-64-56-2.tgi (nes_64_56_2)/</tag>
105 This driver features a resolution of 64×56 with 2 colors using the
111 <sect1>Extended memory drivers<p>
113 No extended memory drivers are currently available for the NES.
116 <sect1>Joystick drivers<p>
120 <tag><tt/nes-stdjoy.joy (nes_stdjoy)/</tag>
121 A joystick driver for the standard four buttons joypad is available.
126 <sect1>Mouse drivers<p>
128 No mouse drivers are currently available for the NES.
131 <sect1>RS232 device drivers<p>
133 No serial drivers are currently available for the NES.
141 The existing library for the NES doesn't implement C file
142 I/O. There are no hacks for the <tt/read()/ and <tt/write()/ routines.
144 To be more concrete, this limitation means that you cannot use any of the
145 following functions (and a few others):
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