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:

Revision 1.7

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.

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.

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.