Atari DOS 2 versions

[cx2k]

I've started archiving all the different versions of DOS 2 that I've found but unfortunately I don't have the programming skills to look at what differences there are, if any.

 

DOS 2.0 - David Young modified (2 different dates), DOS 2S, DOS III (modified DOS 2), DOS 2.6f are just some examples. Some of these I recently just discovered on disks from an Atari employee. In some cases, i suspect, a couple may be just text hacks where someone changes the text, but others seems to indicate they have other features/functions. One version has DOS & DUP at 38 and 41 sectors respectively instead of normal DOS 2.0 with 39 & 42 sectors.

 

Has anyone ever looked into documenting these in the past or feel up to the task?

 

John

 

[+MrFish]

Here are a couple of threads.

 

 

 

 

 

[Rybags]

I don't thing there was any official other than 2.0S.  Additional to that is 2.5.

There were also modded Doses like Long John's.  From memory it just changed some functions like the duplicate disk being a full sector copy instead of using the VTOC map to deduce what to copy.

I also use a modded DOS 2.5 called 2.5XL which has a patch such that it automatically uses Ram under the OS to store DUP.SYS and MEM.SAV.

From memory it was in a magazine and was a pretty short program that ran the patch process.

[+bf2k+]

Was Atari DOS 2.0D not official?  It seems to me that it came on my MMG Compiler disk.  I don't know... I CRS anymore...

Seems like I have DOS 1 here too... maybe not official?  No DUP.SYS on this one but it boots into DUP as it is all one file.

I know I have a few odd flavors like 2.6f and 2.8 but I am pretty sure they are hacks...

 

[Rybags]

I omitted 2.0D since I don't think it went into widespread production.

Dos 1 was short lived.   Realistically there was no reason to persist with it once 2.0 came out.  The fact it was monolithic with DUP always hogging the extra memory being one of the prime reasons.

[BillC]

I believe DOS 2.0D was only released with the 815 drive, there were only 100 815 drives made and most were returned due to technical problems.

[+DjayBee]

14 hours ago, BillC said:

I believe DOS 2.0D was only released with the 815 drive,

MMG BASIC compiler v2.0 had it on its side B as @bf2k+ remembers correctly. 

[+MrFish]

59 minutes ago, DjayBee said:

MMG BASIC compiler v2.0 had it on its side B as @bf2k+ remembers correctly. 

I'd never heard of this; but I can see it's in the preserved software archive. I guess it wasn't something that mattered much to people; so, only single density copies proliferated down through the years.

 

[+kheller2]

Well, Atari didn't have any DD drives (At that time).  And if you modified your drive to be DD with an add on you probably were using another DOS already anyway.

I don't think 2.0D can read 2.0S, not because of logical issues but because D was DD only.

[cx2k]

20 hours ago, MrFish said:

Here are a couple of threads.

 

 

 

Thanks for pointing those out. Some good info but not much dissection of the actual changes other than someone mentioning the David Young version doing a sector copy and write verify turned off.

 

I really wish I had the ability to dig into the code like some of the amazingly talented folks here but unfortunately I don't. Still would love to see someone tackle this.

 

John

 

[+DjayBee]

12 minutes ago, kheller2 said:

I don't think 2.0D can read 2.0S, not because of logical issues but because D was DD only.

This is definitely true for Atari's release but the MMG release contains a configuration program which IIRC allows to select the density per drive.

I have not tried the program, which is why I am not sure.

 

If somebody wants to check it:

https://archive.org/details/cssa8d_MMG_Basic_Compiler_v2_0_1984_MMG_Micro_Software_US

 

[+kheller2]

5 hours ago, DjayBee said:

This is definitely true for Atari's release but the MMG release contains a configuration program which IIRC allows to select the density per drive.

I have not tried the program, which is why I am not sure.

 

If somebody wants to check it:

https://archive.org/details/cssa8d_MMG_Basic_Compiler_v2_0_1984_MMG_Micro_Software_US

 

Actually, Side 2 of that boots into "DISK OPERATING SYSTEM II DOUB.DENS.V2"  and I see no configuration program. And I have no idea what this is, other than maybe a hacked up DOS 2.0S to support D (which i think was doable).

 

Now side 1 boots into the same thing, but does have a conversion program to change what each drive is.  But typing the number of the drive doesn't seem to change anything and keeps it at DD.  Exiting the program wants me to boot up side 2.  So this seems to just change what the drive type is, but always setting it to DD.

 

I'm much more interested in DOS 2.71/2.75 now that I got ahold of the German docs.  I'm curious what they "fixed".

 

[BillC]

3 minutes ago, kheller2 said:

And I have no idea what this is, other than maybe a hacked up DOS 2.0S to support D (which i think was doable).

DOS 2.0S is capable of booting in double density, I configured a USD drive as D2: in the late 80's, then ran a BASIC utility to configure the PERCOM block to double density/ formatted a blank disk and wrote DOS to it. The main issue was the inability to switch densities.

[+DjayBee]

The difference between 2.0S and 2.0D are only a few bytes. 

[+kheller2]

I would think the main difference is DUP.  Dos.sys should already know how to handle 810 vs 815. 

[+CharlieChaplin]

On 5/19/2023 at 8:57 PM, kheller2 said:

Well, Atari didn't have any DD drives (At that time).  And if you modified your drive to be DD with an add on you probably were using another DOS already anyway.

I don't think 2.0D can read 2.0S, not because of logical issues but because D was DD only.

 

I read somewhere that if you press Reset in DOS 2.0d, then it can read DOS 2.0s disks.

There is also a patched version of DOS 2.0 that allows for changing the density (menu option P, change density), unsure if it was from the MMG disk. That version has 39 sectors for DOS.SYS and 44 sectors for DUP.SYS. See attached ZIP file, you can change density and then write it onto a 90k disk or image (and also boot that 90k image).

Besides, the DOS.SYS of SmartDOS is DOS 2.0 from Atari, they were allowed to use it for their DOS and added lots of utilities/add-ons in the DUP.SYS portion. One of the utilities is the change density option.

 

Think those DOS 2.5f (before DOS 2.5 was out!), 2.6f, 2.8f, 4.0 (before 4.0 was out!), 8.0, etc. are all the same versions, someone took DOS.SYS from DOS 2.0 and added a 76 sector file and named it DUP.SYS, then changed some texts (version number, author credits) and the colour. Funny thing is, you can also do that with DOS 2.5 from Atari, just delete the DUP.SYS there and copy the 76 sector DUP.SYS over, alas, the utilities of that 76 sector DUP work only with single density and 720 sectors...

 

DOS2f.zip DOS20D_change_density.zip

[+CharlieChaplin]

19 hours ago, kheller2 said:

I'm much more interested in DOS 2.71/2.75 now that I got ahold of the German docs.  I'm curious what they "fixed".

 

 

According to the author 13 serious bugs were fixed (afair, one bug would format drive 1 instead of drive 8 / ramdisk). But I have been told, that the original DOS 2.5 works with Pokey divisor zero, while the fixed version 2.71 does not (and 2.75 was just a number change nothing more, I simply did this, since I wanted to have 2 and 5 still in the version number)...