Re: How to make .nib disk images?

[Rubywand <rubywand@swbell.net>]

Matthew Russotto writes ...
> 
 ....

> The Trinity on Asimov is simply corrupt.  The format is OK, both the
> "18-sector" side and the 16-sector side, but the data is damaged.
 ....

     Yes; that's very likely. However, at least on the .nib images I
checked (in sets from 1999 and 2001), the formatting was messed up, too.

     It turns out that Side 1 of the original disk is formatted for
17 sectors/track. (A scan of the side for the address header bytes used
gave 595 hits. 595sectors/35tracks = 17 sec/trk.)

     Both of the .nib images checked had Side1 formatted for 16sec/trk.
Since Side 1 seems to be mainly or entirely the 'program side'-- it's
never used again once Side 2 is inserted-- the difference is probably
not critical. Most of the side is likely to be unused and it would be
relatively easy to deprotect the side and write everything in 16 sector
format.

     The big problem is Side 2. The original seems to be formatted for
35 track-size "sectors". Both of the Side 2 .nib images checked were
formatted for 16sec/trk. The original Side 2 can hold a lot more data;
and, it seems to be nearly full.

     This could explain why the game run from the .nib images seems to
play okay during the early stages. Eventually, though, we run out of
space and some data is omitted or over-written. The game begins to
show hashed up messages and finally crashes.


     Anyway, the information supplied by Greg Nelson on how to make .nib
images led to a fresh attempt at getting good .nib images for "Trinity".
I tried out the new images on AppleWin yesterday. Based upon playing the
game through to the end and winning, it looks like they're okay.

     Information about the new images with download links is available
on GS WorldView at http://www.apple2.org.za/gswv/a2zine/gswv/index.html .
Click on "Trinity: New Image of an Infocom Classic".


Rubywand