SDX and DOS 2.5 Enhanced disk format

[TGB1718]

So I created a DOS 2.5 enhanced disk image using Altirra, but when I DIR the disk it says 720 Free Sectors.

So I boot a DOS 2.5 disk and format the image which it does and creates an ED disk (so the image under Altirra is the right size).

I copy some file to the new disk and also put DOS on it:

 

All looks good with 819 free sectors

 

Leave disk in and boot with SDX U1M in Altirra and this is what I see

 

 

Only 516 sectors free (so seeing it as single density)

 

Now this is where is gets weird, leave disk in and reboot to DOS 2.5 and this is what I now see

 

 

It's now a single density disk ????

 

Not sure if this is an Altirra or SDX issue, might try on real hardware later, but thought I was losing the plot

as I was sure yesterday I created an ED disk needed for extra data and today the disk was full, on checking

I saw it was now single, so did some checks.

 

 

[TGB1718]

Ok, copied those images to an S-Drive-MAX booted to DOS 2.5 and both images came up as ED disks, formatted

one and copied files over, wrote DOS and still a nice ED disk.

Re-booted (130XE U1M with SDX) and both disk come up as Single Density when doing a DIR

so it looks like something SDX is doing, anyone else see this behaviour ?

[_The Doctor__]

Nowhere in your steps do I see you making any SDX writes to the disk, SDX will not modify a disk if you do not perform a write to disk function. ED is read only in SDX. It is not SDX at that point but rather a reset/warmstart/coldstart/memory issue of some kind possibly in conjunction with whatever combination of device/emulator you are using.

Edited July 29 by _The Doctor__

[drac030]

58 minutes ago, TGB1718 said:

Leave disk in and boot with SDX U1M in Altirra and this is what I see

 

 

Only 516 sectors free (so seeing it as single density)

 

[TGB1718]

32 minutes ago, _The Doctor__ said:

Nowhere in your steps do I see you making any SDX writes to the disk,

Correct, not doing any writes, just a DIR so shouldn't be getting those results, but I am, hence asking if anyone else see's this issue.

The fact it does the same thing under SDX on real hardware although using an S-Drive shows there's something wrong, probably

with the way SDX reads ED DOS 2.5 disks

[TGB1718]

@drac030 thanks for your information, however I didn't do any disk writes, just booted and did a DIR and SDX

is not showing the extra sectors.

[drac030]

3 hours ago, TGB1718 said:

just booted and did a DIR and SDX

is not showing the extra sectors.

Because it supports the DOS 2.5 format read-only. I.e. if you save a file in DOS 2.5, and a part of that file is outside the first 720 sectors, it can be read, but these sectors cannot be written to. This is why they are not shown in DIR - they are not available.

[TGB1718]

Ok, makes sense, thanks again