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osd-contiki/cpu/6502/README.md
Oliver Schmidt 91beb8670f Added SLIP support to retro platforms. 
The cc65 tool chain comes with V.24 drivers so it seems reasonable to use the existing Contiki SLIP driver to implement network access via SLIP as alternative to Ethernet.

Some notes:
- The Ethernet configuration was simplified in order to allow share it with SLIP.
- The Contiki SLIP driver presumes an interrupt driven serial receiver to write into the SLIP buffer. However the cc65 V.24 drivers aren't up to that. Therefore the main loops were extended to pull received data from the V.24 buffers and push it into the SLIP buffer.
- As far as I understand the serial sender is supposed to block until the data is sent. Therefore a loop calls the non-blocking V.24 driver until the data is sent.

On all platforms there's only one V.24 driver available. Therefore V.24 drivers are always loaded statically.

On the Apple][ the mouse driver is now loaded statically - independently from SLIP vs. Ethernet. After all there's only one mouse driver available. However there's a major benefit with SLIP: Here all drivers are loaded statically. Therefore the dynamic module loader isn't necessary at all. And without the loader the heap manager isn't necessary at all. This allows for a reduction in code size roughly compensating for the size of the SLIP buffer.
2017-02-15 23:43:28 +01:00

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6502

The cpu/6502/ directory is used for targeting 6502-based machines using the cc65 compiler http://cc65.github.io/cc65/.

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 for Ethernet:

  • 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)

It has the following format for SLIP (based on RS232 driver coming with cc65):

  • 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 - 21: struct ser_params (see cc65 serial.h)

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 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:

  • WITH_SLIP

    • Default: 0
    • Purpose: Use SLIP (based on RS232 driver coming with cc65) instead of Ethernet.

  • MTU_SIZE

    • Default: 1500
    • Purpose: Set the Maximum Transfer Unit size.

  • CONNECTIONS

    • Default: 2
    • Purpose: Set the maximum number of concurrent TCP connections.

  • STATIC_DRIVER

    • Default: N/A
    • Purpose: Link device driver statically instead of loading it dynamically using the network configuration file.

  • WITH_LOGGING

    • Default: 0
    • Purpose: Have log_message() and UIP_LOG() 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_80COL

    • Default: 0
    • Purpose: Enable 80 column screen.

  • WITH_GUI

    • Default: 0
    • Purpose: Initialize the CTK process on startup.

  • WITH_MOUSE

    • Default: 0
    • Purpose: Enable CTK mouse support and load a mouse driver.

  • STATIC_MOUSE

    • Default: N/A
    • Purpose: Link mouse driver statically instead of loading it dynamically.

  • WITH_ARGS

    • Default: 0
    • Purpose: Enable support for contiki_argc / contiki_argv.

  • WITH_PFS

    • Default: 0
    • Purpose: Implement the CFS interface with a Platform-specific File System instead of the POSIX file system.