
    $Id: NSD-History 1.4 1997/05/15 18:11:48 heinz Exp $


History & Conformance
=====================

This chapter will tell you about changes in different versions of
NSD and about the reasons behind the changes.

The most recent changes are at the top of the list:

    - Public Revision 1.6: Minor text cleanups and clarifications
      for publication on ftp.amiga.de. No substantial changes.

    - This version of NSD fixes an obvious typo in the
      define list that nobody noticed or reported previously.

      The correct define name for audio type devices is:

        #define NSDEVTYPE_AUDIO         8   /* like audio.device */

      It used to be documented as NSDEVTYPE_AUDIOARD, which is
      wrong.

      The text "large enough" describing the mn_Length check has
      been replaced with a description of "at least the minimum
      required size". It had turned out that people misunderstood
      "large enough" as meaning "exactly of the required size",
      which is obviously wrong in the context of devices supporting
      multiple request sizes for different types of commands.

      Similar to the change mentioned above, other places have been
      reworded to avoid misunderstandings.

      The basic NSD command set description reflects the
      distinction between command set and semantic consequences
      now by elaborating on the device types. There is also a
      description now on the standard V40 command slots for the NSD
      device types.

      The NSDEVTYPE_TRACKDISK specific section has been extended
      with a description for ETD like commands. Also, a note has
      been added that e.g. the V40 cd.device as used by C= for the
      CD32 game system should not be forgotten. It is a C= V40 OS
      device "like trackdisk", too. General clarification comments
      have been added in various places.

      Notes for NSDEVTYPE_SANA2 have been added.

      As it turns out, NSD is not only about identifying device
      capabilities, but also about safe use of a device as a
      consequence. While 100% safety can probably never be reached
      within the existing frame, there are simple ways to make
      usage of devices a lot safer. The text now reflects this.

      Due to the complexity of the issues involved, the document
      has been split into sub documents. The wording has been
      changed in several places to reflect this.

      Additionally, a "Thoughts & Consequences" section, a "Future
      Directions" section, and this "History & Conformance" section
      have been added as sub documents.

      The requirement of changing TD_GETDRIVETYPE for NSD
      trackdisk like devices has been removed. The DRIVE_NEWSTYLE
      identifier for trackdisk like devices doesn't serve any
      useful purpose. It never has and has been introduced only
      because of an oversight during the revision process. While
      the trackdisk TD_GETDRIVETYPE command generally isn't exactly
      the most useful command in the world currently, and while it
      has been documented that anyone using a new style device
      should use TD_GETGEOMETRY, redefinition of TD_GETDRIVETYPE is
      obviously not a useful thing in this context and it would mess
      up the implementation of a true NSD trackdisk.device
      replacement.

      The NSD recognition sequence contains an additional simple
      check now. Correctly written software will continue to work
      well, and software written now will be safer.

      A recommendation has been added on how to set up a reused
      request structure for another OpenDevice() to do a general
      NSD query. As some strange device expect parameter data being
      set up on an OpenDevice() call, the request structure should
      not contain or point to garbage data.

    - Revision 1.4 of NSD got published soon after the release of
      the Amiga Developer CD 1.1. It added the requirement to check
      mn_Length in OpenDevice for at least the minimum required
      size to be handled by the device and documented the "safer
      assumption" for querying a device. It had turned out that
      SANA devices can barf on a general query. As a device
      implementing the mn_Length check will at worst fail to open
      instead of messing up the system which could have happened
      previously, NSD got safer and better this way. A client not
      using the safer assumption is more likely to fail with bad
      devices, but it will still work with the updated NSD spec if
      it doesn't have bugs.

    - Revision 1.0 of NSD, as published on the Amiga Developer CD
      1.1, unfortunately had no RCS Id string. It should
      be referred to as NSD revision 1.0.


*** EOT ***
