What is it with SDX and ED Atari DOS 2.0/2.5 disks?

[woj]

It seems SDX cannot handle these properly, regardless how I create them (dir2atr or Altirra). For an empty disk, SDX reports rather low free space in sectors, format cannot handle Atari DOS FS and Medium Density. Also, if a file larger than the reported 707 sectors is copied to the disk externally (again, dir2atr or Altirra disk explorer), it can be fully and correctly read by SDX, but the free space is 0 sectors. The same file cannot be copied to the same disk from within SDX, it says disk full. An existing (in my case below one sector) file cannot be overwritten either if the disk is sufficiently fully (presumably over these 707 sectors).

 

(MyDOS ED disks seem to work, but I specifically need to know what the story with the Atari DOS ED disks plus SDX is...). 

 

So, a bug @drac030? Or is there something I do not grasp?

[drac030]

The ATARIDOS.SYS driver has never supported the DOS 2.5 enhanced density. Quoting the manual:

Quote

It supports all the derivatives of AtariDOS 2 including subdirectories in MYDOS up to a size of ~16 MiB (65535 sectors, 256 bytes each). It supports the extended sectors of DOS 2.5 for read only.

It has been so since ICD times, and nobody cared to add the write support.

[woj]

5 minutes ago, drac030 said:

The ATARIDOS.SYS driver has never supported the DOS 2.5 enhanced density. Quoting the manual:

It has been so since ICD times, and nobody cared to add the write support.

I see. I did scan the manual, but very quickly and did not find this piece of info. Makes perfect sense now. Many thanks!

[+MrFish]

On 12/20/2023 at 4:41 PM, drac030 said:

It has been so since ICD times, and nobody cared to add the write support.

Why? It was an extremely common format that was used on a lot of disks.

 

[+Stephen]

2 hours ago, MrFish said:

Why? It was an extremely common format that was used on a lot of disks.

 

My guess would be that many got Sparta DOS with the US Doubler, and at that point, had no reason for the 127kB disks.  I've been using Sparta since 1987 that way, and until this thread, I did not know it couldn't write to an enhanced density disk.

[+MrFish]

10 minutes ago, Stephen said:

My guess would be that many got Sparta DOS with the US Doubler, and at that point, had no reason for the 127kB disks.

Good point, and probably the case in many instances. Nobody was ever clamoring for ED support in SpartaDOS.

 

[+bf2k+]

I know in all my years, I have almost never used an enhanced density disk for anything.

 

As Stephen pointed out, I got my US Doubler(s) about the same time I started using SpartaDos exclusively... probably around 1985 or so.

[drac030]

10 hours ago, MrFish said:

Nobody was ever clamoring for ED support in SpartaDOS.

A reason may be that SpartaDOS does handle the ED - just not in DOS 2.5 format. And once you switch to the SpartaDOS format, you probably hardly ever need to create new DOS 2.5 ED disks (like OP: once in 35 years).

[+kheller2]

Same with me. The USD came with SDCS and I never needed to write ED after that.  It could read it, if need be... but after going DD, I never looked back.

[bfollowell]

As my first and only 8-bit drive until just a few years ago was a Rana 1000, and an XF551 after the Rana died, I only used single and double-density, so it was never a problem for me. I have a 1050 now, but it has a Happy mod and is double as well so, other than maybe wanting to read the odd ED disk if I stumbled onto one sometime, I'd never use it. There's definitely no need for me to ever want to write one. Honestly, I have no need to write any disks of any density. All I do is read and archive now. I know there are still a lot of users that love to use real media though.

 

[+Larry]

My recollection is MyDos can Read but not Write the Dos 2.5 format ED.  But I believe that Sparta can read the MyDos ED, and naturally DD.  I'm pretty sure that is how I used to convert Dos 2.5 ED to MyDos.  It's an extra step if your goal is actual Sparta format, but it should work.  I never cared much for ED, but as mentioned, there were quite a lot of disks in that format.

[drac030]

8 hours ago, Larry said:

My recollection is MyDos can Read but not Write the Dos 2.5 format ED.  But I believe that Sparta can read the MyDos ED, and naturally DD.  I'm pretty sure that is how I used to convert Dos 2.5 ED to MyDos.  It's an extra step if your goal is actual Sparta format, but it should work.

To convert a file from DOS 2.5 ED floppy to SDFS, it is enough to just copy it. SpartaDOS reads the entire diskette without a problem.

 

But in the other direction, a DOS 2.5 ED disk is seen as a single density 90k DOS 2.0 media. Therefore you can write files up to the point where the DOS 2.0 707 free sectors are exhausted.

 

This is what these words: "It supports the extended sectors of DOS 2.5 for read only" mean - the "extended sectors" are sectors 721-1023 of a DOS 2.5 ED diskette.

 

And that is what OP was trying to do: copy a 100+ KB file to a DOS 2.5 ED disk. It won't work, because the write limit here is 707 sectors.

[woj]

1 hour ago, drac030 said:

And that is what OP was trying to do: copy a 100+ KB file to a DOS 2.5 ED disk. It won't work, because the write limit here is 707 sectors.

Hold on, so if the short file I want to overwrite happens to be located "early" it should work, regardless of the rest of the disk being almost full? (Will have a chance to check myself later anyhow, just had an epiphany).

[woj]

3 hours ago, woj said:

Hold on, so if the short file I want to overwrite happens to be located "early" it should work, regardless of the rest of the disk being almost full? (Will have a chance to check myself later anyhow, just had an epiphany).

Right, quoting myself, yes, if the file sits below the mentioned boundary, SDX if happy to write it. What is not working is - there is no way to make dir2atr place files on the disk in a particular order, had to revert to Altirra to do that. The other thing that is not working, the XBOOT mini DOS I used otherwise on the same disk is no longer happy to write into that small file placed at the beginning of the disk.

 

Edited December 23, 2023 by woj

[woj]

So for future generations: the files that sit in the safe below sector 707 region are SDX writeable. XBOOT could also be made to work with ED disks by adding a couple of opcodes to recognize both $03 and $42 file flags. (Since the XBOOT version I am talking about can only work with single sector files for writing this should be safe). As for creating the correctly sorted ATR disks with dir2atr, I had to hack the AtariSIO project sources, luckily there is actually a flag not to sort the directory when getting the files from it, so it just needed activation (though I still tripped over one thing there too, but never mind that). In the end I got everything to work the way I wanted. 

 

Thanking everyone for help, especially @drac030, my rant about 40+ year technology that still constantly need fixing for achieving small and simple things (am I too demanding to have ED disks working seamlessly with my game?) remains... 😕 

[Forrest]

The ED 130K format never caught on, because double density drives were available for sale a year or so after the 1050 Drive hit the market. The Indus GT and Rana drives were sold for about the same price, but had double density and a track display. Coupled with the release of MyDos, which looked very familiar to those used to working with DOS 2.0 it was an easy upgrade. If you had two drives, it was simple to copy files from a 90K SD floppy to a 180K DD floppy - so you didn’t have to keep buying floppy disks. ICD’s USDoubler was an inexpensive upgrade for the 1050 Drive to go DD.

[ggn]

17 hours ago, Forrest said:

The ED 130K format never caught on, because double density drives were available for sale a year or so after the 1050 Drive hit the market. The Indus GT and Rana drives were sold for about the same price, but had double density and a track display. Coupled with the release of MyDos, which looked very familiar to those used to working with DOS 2.0 it was an easy upgrade. If you had two drives, it was simple to copy files from a 90K SD floppy to a 180K DD floppy - so you didn’t have to keep buying floppy disks. ICD’s USDoubler was an inexpensive upgrade for the 1050 Drive to go DD.

When I got an XF551 with DOS 2.5 in the late 80s, without Internet or pretty much any other Atari resource apart from some Atari User issues, I knew no better. Heck, I didn't even know that the 551 could do double density up until a few years ago. So, all my disks were formatted ED.

[Forrest]

Atari User Groups were a big source of info in the 80’s. Many groups exchanged newsletters with each other to share the knowledge.

[Marius]

Years and years ago... when I was still a very young person, around 13 years old, I got my very first 1050 diskdrive. A stock one. A world opened. But back in that time it was also rather common to have DOS 2.0s on floppy disks. So, without knowing anything yet, I started using DOS 2.0s and 2.5 mixed. And of course I found out (Without knowing anything about formats or sectors) that DOS 2.5 gave me these 999+ free sectors, and DOS 2.0s only 707 free sectors. So the choice was made pretty easily: I would format my disks with DOS 2.5. 

 

I already emphasized that I did not know a thing about this, so pretty soon the frustrations started to occur. What is wrong with this diskdrive? What is wrong with these floppy disks? I couldn't access sometimes these files and sometimes they were even invisible. It drove me rather crazy. Until I found out about this difference and the feature. 

 

You are actually running in the same thing, although not as 'severe' as I did. You were still able to read the files, and they appeared to you. But the problem lies in the same reason.

To be honest, once I found out, I did not like the ED format that much anymore. Rather incompatible in the entire eco-system of formats. Later I started using it again, with the GAME DOS, which name I forgot... there was a special 'medium' formatter available to have 1000 sectors available for games. If I remember correctly it was called SpeedStart INIT+ by Reuss. But I can be mistaken, of course. Then it was pretty cool to have 1000 sectors available on a stock 1050. 

 

Today I try to stick with SD or DD. It makes way more sense. Both the same amount of sectors, but simply 128 or 256 bytes / sector. But still... even then I run into problems when I have only a stock 1050 available. I am probably one of the minority of people who still likes a stock 1050. (Although my main 1050 is upgraded with the Mini Speedy).

 

[woj]

19 minutes ago, Marius said:

You are actually running in the same thing, although not as 'severe' as I did. You were still able to read the files, and they appeared to you. But the problem lies in the same reason.

For me it is simply a nice learning experience, hacking the xBoot DOS (with the 4-5 bytes left in it) to support ED disks was just a time nice spent, I learned a lot in the process. Another thing I just learned (never ever owning a real disk drive for those machines, and probably not going to due to inaccessibility of the actual disks) is that the baud rate speed ups and mods for all the drives are partly theoretical, I was so surprised (working with Altirra with the accurate timing disk emulation) that the practical speed up is almost negligible due to sector timings and all, even with HSIO and all I could not experience a speed up like with SDrive at all. What did improve things was going DD and doubling the sector size on top of the speed mods. All very very interesting. 

 

(All this discussion would not even take place if I were a bit less lazy and compressed my game into a 90K disk size, which I think is doable, but also rather difficult and requiring a major code refactoring).

[Marius]

13 minutes ago, woj said:

For me it is simply a nice learning experience, hacking the xBoot DOS (with the 4-5 bytes left in it) to support ED disks was just a time nice spent, I learned a lot in the process. Another thing I just learned (never ever owning a real disk drive for those machines, and probably not going to due to inaccessibility of the actual disks) is that the baud rate speed ups and mods for all the drives are partly theoretical, I was so surprised (working with Altirra with the accurate timing disk emulation) that the practical speed up is almost negligible due to sector timings and all, even with HSIO and all I could not experience a speed up like with SDrive at all. What did improve things was going DD and doubling the sector size on top of the speed mods. All very very interesting. 

 

(All this discussion would not even take place if I were a bit less lazy and compressed my game into a 90K disk size, which I think is doable, but also rather difficult and requiring a major code refactoring).

Speaking of this... I was always slightly jealous of my Apple //c computer. It has a built-in 5.25" diskdrive, and if I am informed correctly this Drive is using PARALLEL I/O instead of SERIAL. That makes it lightning fast. Copying a 5.25" floppy with LockSmith fastcopy is a matter of a few seconds (seriously, the only thing that takes some time is formatting). Even the fastest upgrade on a 1050 is still a slow snail compared to that Apple //c floppy drive. 

Oh and do you mean floppy disks with software, or empty ones... that seem not to be available? Here in the Netherlands it is indeed also quite a challenge to find these disks. But still... every now and then on a local market site I see them offered (sometimes even new and sealed) and then I always do a bid. It is nice to have some spares here. Nothing beats the real thing.

 

[drac030]

27 minutes ago, woj said:

Another thing I just learned (never ever owning a real disk drive for those machines, and probably not going to due to inaccessibility of the actual disks) is that the baud rate speed ups and mods for all the drives are partly theoretical, I was so surprised (working with Altirra with the accurate timing disk emulation) that the practical speed up is almost negligible due to sector timings and all, even with HSIO and all I could not experience a speed up like with SDrive at all.

They are not theoretical, the speedup is real, for instance, with UltraSpeed, the disk drive becomes about twice as fast, BUT you also have to format your floppy with the fast interleave (aka turbo sector skew). If a floppy disk is formatted to the standard interleave, improving the baud rate does not speedup anything indeed. Worse even, using standard baudrate with fast interleave makes the thing even slower than standard.

 

31 minutes ago, woj said:

(All this discussion would not even take place if I were a bit less lazy and compressed my game into a 90K disk size, which I think is doable, but also rather difficult and requiring a major code refactoring).

The simplest thing to do seems to be to use the double density image.

[woj]

13 minutes ago, drac030 said:

They are not theoretical, the speedup is real, for instance,

Unfortunate wording on my side What I meant is that it took me a while to setup Altirra in a way were I could actually see the speed up. For example, choosing fastest possible 128K drive does not do much with accurate sector timing and (most probably) not choosing the right interleave, I still did not manage to figure out which one it should be. But yes, thinking about it, having the actual 5 1/4" drive work twice the factory speed is an achievement, I live too much in the world of SDrive and SIO2SD things And also yes, now I can see that the ED format is the odd one out, even though someone around here did advise me to go for it a while back. 

[drac030]

15 minutes ago, woj said:

not choosing the right interleave, I still did not manage to figure out which one it should be

I doubt if there is even an established "correct" interleave for 128 kbps. Especially that there is no universal correct interleave for a baudrate, because this also depends on the disk drive's rotation speed, efficiency of the firmware etc.

 

In any case the correct question is not "what is the baudrate" but "in how many rotations a track is being read". It is 13 rotations for 1050 in ED, and 7 rotations for an US Doubler in same density (but with fast sector skew).

[+kheller2]

Bah!  Track buffer makes baud rate very important for speed. Nothing like reading a disk as if it were being formatted.