Added some info on the high-level config macros (and other stuff).

cpu/6502/README

@@ -1,13 +1,76 @@
 The cpu/6502/ directory is used for targeting 6502-based machines using the cc65
 compiler (http://www.cc65.org/). In almost all cases it is preferable to go for
 a recent snapshot instead of the latest official version. The most recent cc65
-snapshot is available at: ftp://ftp.musoftware.de/pub/uz/cc65/snapshot/.
+snapshot is available at ftp://ftp.musoftware.de/pub/uz/cc65/snapshot/.
+
 
 The Contiki network configuration for 6502-based targets is loaded from a binary
 configuration file (by default named contiki.cfg). It has the following format:
+
 - Bytes  1 -  4: IP Address     (HiByte first)
 - Bytes  5 -  8: Subnet Mask    (HiByte first)
 - Bytes  9 - 12: Default Router (HiByte first)
 - Bytes 13 - 16: DNS Server     (HiByte first)
 - Bytes 17 - 18: Ethernet card I/O address (LoByte first !)
 - Bytes 19 - xx: Ethernet card driver name (ASCII / PETSCII)
+
+An online Contiki configuration file generator is available at two sites:
+
+- http://www.a2retrosystems.com/contiki.htm
+- http://www.cbm8bit.com/contiki/
+
+
+The build for 6502-based machines includes the 'disk' make goal which creates a
+bootable floppy disk image containing the project binary, a sample configuration
+file and the Ethernet card drivers.
+
+
+The 6502-based targets do in general not support keyboard input or screen output
+through stdin, stdout and stderr.
+
+
+The build for 6502-based machines supports so-called high-level configuration
+macros which allow to customize Contiki on a per-project basis. They are set
+in form of a comma-separated list as value of the make variable DEFINES on the
+make command line. The value of DEFINES can be saved with the 'savedefines' make
+goal. The values of the high-level configuration macros are not tracked by the
+build so a manual rebuild is necessary on any change. The following high-level
+configuration macros may be set:
+
+MTU_SIZE
+- Default: 1500
+- Purpose: Set the Maximum Transfer Unit size.
+
+WITH_LOGGING
+- Default: 0
+- Purpose: Have log_message() write messages to the screen.
+
+WITH_BOOST
+- Default: 0
+- Purpose: Significantly improve troughput on sending full sized packets by
+           splitting them thus workarounding the "delayed acknowledge".
+
+WITH_FORWARDING
+- Default: 0
+- Purpose: Enable support for the 'IP forwarding' packet driver.
+
+WITH_CLIENT
+- Default: 0
+- Purpose: Enable support for outgoing TCP connections.
+
+WITH_DNS
+- Default: 0
+- Purpose: Enable UDP support and initialize resolver process on startup.
+
+WITH_GUI
+- Default: 0
+- Purpose: Initialize the the CTK process on startup.
+
+WITH_MOUSE
+- Default: 0
+- Purpose: Enable CTK mouse support and load a mouse driver.
+
+WITH_PFS
+- Default: 0
+- Purpose: Implement the CFS interface with a Platform-specific File System
+           instead of the POSIX file system.