08/11/13: Accessing read/write to/from disk under pure assembly language by CoCoJon, | Category: General, Programming | 2 comments - (Comments are closed)

Accessing read/write to/from disk under pure assembly language


I have some questions pertaining to disk access from pure assembly language on a CoCo 3 …

(1) Is there a special way to know whether a computer is running HDB-DOS from assembly language?

(2) What DECB commands are supported in assembly language from HDB-DOS? Does HDB-DOS maintain backward-compatibility with DECB when it comes to implementing DECB commands? I have the book “Disk BASIC Unravelled”. Will that be of any use under HDB-DOS?

(3) I noticed that someone from the CoCo Mailing List recently asked whether there is such a thing as HDB-DOS Unravelled. Is there?

I will probably have additional questions based upon the responses to the above questions. I am currently working with CoCo_Jay on a text-based video game that will utilize the CoCo 3’s 80-column text mode.

Thank you for your help.


This post was submitted by CoCoJon.

2 comments to Accessing read/write to/from disk under pure assembly language

  • Robert Gault

    Since HDBDOS is an enhanced Disk Basic, it is backwards compatible with Disk Basic.

    You probably can tell if RGBDOS or HDBDOS is installed by examining the contents of $D936. If it is $3476, then HDBDOS is installed.

    There aren’t any DECB commands that are supported in the strict sense from assembly language. There is a table of entry addresses at $C000-$C00B and these are used by HDBDOS.

    If you want specific information about HDBDOS, you can look at the assembly code by going to Sourceforge and looking for the Toolshed project.

  • CoCoJon


    Thank you so very much for your help. I appreciate it.