Changing the physical format of a disk truncates data that should be saved

[yosinda]

Cause:
The core does not have the ability to extend the size allocated to a track in an existing D88 image file.
If you change the physical format to expand the size of a track, the core truncates the data that does not fit.

Workaround:
Use a disk image with sufficient track size as the blank disk.

Blank_disk_2D.zip

[yosinda]

Details:

For PC88, the N88-BASIC format is commonly used.
However, third parties have changed the sector size to allow for larger capacities.

N88-BASIC: 256 bytes/sector x 16 = 4,096 bytes/track
Example A: 512 bytes/sector x 9 = 4,608 bytes/track
Example B: 1,024 bytes/sector x 5 = 5,120 bytes/track

The blank disk image file is created to fit the N88-BASIC format.
Also, each sector has a 16-byte header in D88 image.
The size of one track is 4,352 bytes.

(256+16)*16= 4352

Formatted with example A, it is 4,752 bytes.

(512+16)*9= 4752

The last sector has 400 bytes that are over the image file allocation, so it is truncated by the core.

When the image is loaded, the missing 400 bytes are read from the beginning of the next track.
The data in the last sector is not what the program is expecting, resulting in strange behavior.

[wwark]

Thank you for thé sharing

[yosinda]

If you are having issues with a game that requires you to create a "user disk" from a blank disk,
please try creating one using the blank disk attached to my 1st post.

[wwark]

Ok I'm not my home for some days will try it and new PR !
Have a nice day !