Atari ST TOS improving, added features by PP in 2018-2021
Overview, instructions
  Why dealing with very old Atari ST TOS in 2018++ ? Simple answer is that there are things which could be done better. Especially work with hard disks. And since in this years floppy drives and disks become more and more problem, unreliable, while Flash card storage becomes cheaper and cheaper, it is normal that people replaces floppy drives with mass storage.

Main improvements: better work with hard disks, real FAT16 filesystem. What is in TOS 1.00-4.xx is rather FAT15, and is not compatible with widely used DOS FAT16, despite using Low Endian byte order . So, that's corrected. iTOS can work with partitions of size up to 1 GB, and 30 of them. TOS 1.04 -4.02 can work with max 14 partitions of max size of 512 MB. In case of 1.00 and 1.02 max size is 256 MB. And iTOS does it with even less RAM and faster.

Virtual Floppy: possible work with floppy image files instead floppy disks and drive. This is much better than Floppy Image Runner (my SW, btw.) . And there are some new possibilites, like very large image files, so can put content of multiple floppies in single image file.

Other features will be described below.

What TOS versions are improved ?
TOS 1.04 - latest TOS for ST, Mega ST machines.
TOS 1.62 - STE TOS, in big part same as TOS 1.04 - no wonder, both are from 1989.

Since TOS consists from 2 pretty much independent parts - GEMDOS, what initialises HW, works with disks and peripherals, and AES/Desktop, called GEM too - that's part which works with windows, dialogs, so basically GUI . And it is possible to combine GEMDOS from one TOS v. with AES from other TOS v.

TOS 2.06 offers self to use it's AES part - much better Desktop, while it's GEMDOS part is not so compatible with older SW, especially games.
So, there are yet:
TOS 2.14 - combo of 1.04i GEMDOS and 2.06 AES/Desktop - for ST machines.
TOS 2.16 - combo of 1.04i GEMDOS and 2.06 AES/Desktop - for STE machines.
But I can deliver 2.14 for Mega STE too - there is some extra code for init it's extra HW. Same stays for 2.16 .

Despite lot of it added, better disk FAT16  filesystem, all it fits in regular TOS ROM space - thanx to used optimizations of code, some packing used.
And is highly compatible with original TOS 1.04 or 1.62 . RAM layout is same, system vatiables are on same addresses. Can boot regular hard disk drivers for diverse adapters in usual way. AHDI (TOS) type medias, partitions will work fine - new FAT16 handles all it well too. But is recommended to use more efficient DOS type partitions (easy to create with integrated partitioner or special PRG for that) , integrated driver, or special driver for this, what handles up to 30 partitions up to 1 GB . Look that low RAM usage of such driver in YT above.

Other improvements, features:

  Virtual Floppy and Raw Image system
  This could be most useful feature, especially for people with broken floppy drives, bad floppy disks. Of course, only for owners of some mass storage. Now Flash card based ones are most popular.
  Since everything is stored on mass storage, it doesn't need extra RAM. Virtual floppy can be of very large size - like 30 MB, so can place there content of many floppies.
  Gaming support: it can run even games, basically what works with Floppy Image Runner, will work with this too. However, here is support for image changes 'on fly', and Raw Image Access feature, what makes possible running even those hard disk adapted games, but with only 512KB in machine, saves from games can work too . And all it even faster.

Detailed manual for Virtual Floppy usage

Some games already adapted with RIA system

  Some useful info after reset - TOS version, boot stage :
TOS version will be shown (like 1.04i), then countdown starts (normally at 9 secs) . During it can activate diverse changes, run some special SW from TOS ROM self, and like.


Keys - will write here as capitals, but it works with simple key press in lower case mode.

Space:  immediate continuing - aborts countdown and starts boot seq.
P - change to PAL video mode, refresh rate will be 60 Hz. Of course only in color modes
N - change to NTSCvideo mode, refresh rate will be 50 Hz. Of course only in color modes

I - swap (invert) black and white colors

1-9 - purpose is quick and simple environment change, something like boot managers. Instead default A:/, A:/AUTO or same on C: 
AUTO run PRGs, ACC-essories, DESKTOP.INF will load and save to special DIRs on A:/BT  (not much sense) or C:/BT/1-9 .
No need for special subdir AUTO there, just copy PRGs for AUTO run in numbered subDIR. like C:/BT/3 .
So, user can make some configurations for specific usage, tasks, and simple enter that mode, without need to bother with boot manager settings.

T - show TV test pattern - good for checking/setting picture position, size, test proper contrast, brightness ...
Exit test pic. with space key. Note: it is with some overscan. 320x240 px . 16 colors.


R - run integrated partitioner


V - activate Virtual Floppy mode immediately - will activate by last setting, if there is such .

S - run Settings for colors and date/time before Desktop start.  Simplified Control.Acc - no serial, mouse, kb. speed settings, only colors and date/time . No more space in TOS ROM, and I don't see that those settings are much used.


Holding down right shift key will prevent AUTO run - that need to do later, after floppy, hard disk boot .
Messages appearing - like "Floppy boot", "Hard disk boot", "Integrated driver", "Auto run" does not mean that it really executes, because that depends from disk content. Purpose is to see in which stage of boot seq. computer is.

Features for advanced users, only on request:

A - special AUTO run mode - it adds pauses between run of PRGs in AUTO folder, so user can see better messages on screen.

G - Again AUTO run related. It will give more RAM for SW from AUTO folder, because when AUTO run starts GEM (AES) is not started yet, but some RAM for it is already allocated. May be helpful especially with machines with less RAM. But must be aware that if exit that AUTO run SW machine will crash - can not enter Desktop. So just reset Atari instead exit that SW with it's exit button, key ...

E - And more AUTO run complication :-)  This will allow AUTO run of GEM (AES) using PRGs. That's possible with TOS 1.04 and later via setting it in Options, Install Application, then Save Desktop . After that it will run automatically right after Desktop start. With this feature it will run before Desktop start.
Note: there is little confusion with AUTO run and filename extensions. For AUTO run it must be PRG. But PRG stays usually for SW what uses GEM, and that's stupid, since it works not with regular AUTO run. They should make it with extension TOS .
What is usual extension for SW not using GEM .

M - this does same as above, with little + - forces medium res in color mode. Useful when no Desktop.inf saved, or is for low res.  If there is Desktop.inf, and key E not used, resolution will be set according to Desktop.inf data .

TOS v. shown in Desktop Info (instead useless 'all rights ...')
Membot shows start address of RAM free for user programs. It can be much higher than indicated if there is many of  resident SW installed, large hard disk driver buffer, and like. And that might be not good for some SW, what is coded to run only in lower space.

More details:
More screenshots, some videos, prices, HW hints ..

    PP,  Jan 2018.- April  2021.