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SIO 2 IDE 1.0

Howto 1.0 written by Romuald

SIO2IDE (C) 2002 by MMSoft
and the author: Marek Mikolajewski


You've always dreamt of an atari without those cumbersome disk drives. You would like to get rid of those floppy disks and their limited size. You've tried SIO2PC, you found it great but a PC is even more cumbersome than a disk drive... Try SIO2IDE.

You can find information and necessary programs for the SIO2IDE interface in Marek Mikolajewski's page.

This page is just intended to explain how to have the sio2ide 1.0 running in your atari. I had some problems to have it working since the documentation was in Polish (and I can't read it). So this page might help some people around.


> 2.5" Harddrive in your ATARI 8bit

Here is the way to install your sio2IDE 1.0 interface in your atari.

> Installation Howto
Here is a short list of what you'll need:

  • an atari (800xl or 130xe). But notice that if you want to have the 2.5" installed in your atari, the 800xl cartridge trapdoor might be a problem, if you have pics of your 800xl with the hard drive inside send them to me please. I did it on an atari 130xe so there might be some difference with the way to do it on the 800xl (for the installation/soldering only, the software and harddrive setup will remain the same)
  • an atari diskdrive (1050 is ok)
  • a SIO2IDE interface + cinfiguration floppy (atari floppy with Mydos 4.53/4 and
  • a 2.5" hard drive (low consumption, small size, and only +5v power supply which could be taken from inside the atari). A 3.5" disk would not fit inside the atari and there would be the power supply problem (it also needs +12v which you can't find in the atari)
  • a 2.5"->3.5" ide converter since you will have to plug a 2.5" drive on the 3.5" connector of the sio2ide interface
  • some soldering experience (and the necessary equipment) to put the interface in the atari (be careful you can severely damage your atari (and yourself?) if you don't know what you're doing, so proceed only if you CAN do it or have it done by someone with the ability the do it)
  • an electronic plier (or a crimp tool)


> Let's go

1 - Open your Atari and remove the keyboard so that you'll have more room to work.  
2 - along with your sio2ide interface you were supplied a connector (which will be connected to SIO_IO on the interface) , have some wires cut (avoid to make them too short or you may have some problem when connecting that cable to the sio2pc interface, see step 3 for the different soldering options before cutting the wires) and use you plier or a crimping tool to have the wires tightened on the small metal tabs. But don't slide the wires+metal tabs in the connector yet...  

3 - Concerning the length of the wires you have two options:

  • either you have the wired directly soldered on the top of sio port (on the pins of the port), then you'll need something like 10cm wires (to have some liberty to move around) (see pictures )
  • or you can solder those wires on the solder side of your atari motherboard (you will then need more wire length in order to have the wires running from under the motherboard to the sio2ide interface). It you prefer this option, it means you have then to:
    • remove the metal shielding (use a plier to bend the metal clips)
    • unscrew the motherboard
    • then find the sio port solder pads

I chose the quick and dirty pin-soldering option (see pictures).

Solder the wires on the atari SIO port pins #3, 5, 7, 4, 10. Check twice before soldering (pin 1 is easy to find since 1 is written on the motherboard but if you have doubts look at the picture for pin number identification).

[Note: beware if you chose the motherboard solder side option the numbers will be reversed, check twice before soldering]

[Note: I always check if the solder joints are good with a multimeter to avoid surprises later]

Click to enlarge


Click to enlarge

4 - Now you can slide the wires+metal tabs in the connector matching the table below:

1 (see note 1) DATA_IN 5
4 RESET_OUT - (see note 2)
5 GND 4 (see note 3)
6 GND 4
7 VCC 10

[Note 1: SIO-IO pin #1 is to be found on the left of the connector and you can see it written on the sio2ide interface if you look closely]
[Note 2: the RESET_OUT signal is optional, it works without connecting it]
[Note 3: I chose to have a jumper from SIO-IO #5 and #6 and thus only one wire on the SIO pin #4, if you prefer to keep the original pinout then solder one more wire to SIO pin #4]

Click to enlarge
5 - Now you have to find +5v and GND for the harddrive.
Don't do what I did on the picture: I found an easy way to have +5v and GND, I soldered the two wires on the atari power supply socket but I didn't realize that doing this would automatically bypass the atari on/off switch. Thus when I plug the atari's power supply the harddrive begins to spin automatically even if the atari isn't switched ON. That's a very bad idea, find another place to solder those two wires...
Click to enlarge
6 - ok everything is soldered... Click to enlarge

7 - now connect the small SIO cable to the SIO-IO connector of the interface, connect the power supply to the harddrive, the harddrive to the interface (see the picture for the red-pin1 stuff), and voila...

[Note: you may have to find a way to isolate the harddrive and the interface in order to avoid shortcuts, I used paper for testing purposes but something better is easy to find and is highly necessary).

Click to enlarge
8 - Put the keyboard you will need it to configure everything... ;)
But don't put the cover back yet since we will have to access the jumper settings.
Click to enlarge


> SIO2IDE Configuration

Once the interface, solders and wires are ok we have to configure the harddrive to work with the sio2ide interface... Hook up your atari, disk drive and TV but do not switch it on...

Some useful information:

Interface state monitor LEDs:

  • PWR_LED - indicates the interface power supply status
  • SIO_LED - indicates that the SIO command is received
  • BSY_LED - indicates that the Hard Disk is busy or that an error occured
  • IDE_LED - indicates the IDE bus activity (HDD output)


1 - Before switching on your atari set the SIO2IDE jumpers:

Jumper Setting Description
HD1_ZW Off Disk D1: Off
INIT_ZW On Disk swap D1<=>D2
MS_ZW On Master mode

[Note: you should have received your SIO2IDE interface with this jumper setting]

2 - Now insert your Mydos + Fdisk floppy in the 1050
3 - Switch on your atari while holding down the OPTION key to boot Mydos... After some LED activity you should see Mydos menu and the BSY_LED should NOT be active. If that's the case everything is OK. If not check that all your connections are ok and that you set the jumpers the proper way.  

4 - At the prompt type
and then will be loaded (it is the sio2ide configuration program)...

5 - On the first menu screen type 1 to see the master SIO2IDE interface configuration (you can have 2 sio2ide interfaces in your atari). You will then have this menu:

1 - View Disks and SIO2IDE parameters
2 - View Partition Table
3 - View Disks Sequence
4 - Edit Partition Table
5 - Edit Disks Sequence
6 - Exit

Enter 2 to see the partition table.
You will then see the 16 partitions (P1->P16) of the harddrive. Sio2ide 1.0 is limited to 16 partitions with a maximum of 65535 sectors per partition (it depends of course on the hardrive, I did it with a small capacity harddrive and I only had 8 partitions). But even with a 16 partitions harddisk sio2Ide 1.0 will see the partitions 8 by 8 because they are associated to disks and DOSes are limited to eight disks. With the edit disk sequence screen you will be able to access the other partitions by remapping/associating them with different disks. But for the moment, write down on a paper the number of sectors per partition you will need it later on...
Now you can exit Fdisk: press a key then enter 6 and finally 3.
Your computer should now go back to Mydos screen...

6 - You must then change the config of the dos (to tell him the number and the size of the disks to be used)...
At the prompt enter : O
Drive Number or Return: 2
Remove Drive: N
Is Drive Configurable: Y
High Capacity Drive: Y
Drive Size (in sectors): [Note: enter here the number of sectors for the Disk/Partition P2, ex:] 65535

Then we must initialize this Disk/Partition (=format), so enter I at the prompt and then:
Disk to Format: 2
Type (Y) to format Drive 2: Y

You will have to repeat step 6 with every drive from D3 to D8 (D2 is done now and you can't access D9-D16 for the time being). Just replace 2 with the number of your disk and of course the size in sectors (that's why you had to write them down)

7 - you must not forget the boot partition...
In fact we have now prepared partition 2 to 8, but the interface must boot on a DOS partition. You have then to prepare the partition #1 to become the boot partition...
At the prompt enter L then enter
Enter 1 to view the master sio2ide settings
then enter 4 (edit disk sequence)
enter 1 to edit one disk
enter the disk: 2 (disk that you want to modify)
enter the partition: 1 (you want to associate partition 1 to disk 2 to access to the content of the partition 1 when requesting Drive 2 under the DOS)
then enter 2 to save the changes, enter 3, 6 and 3 to return to the DOS screen.
Then repeat step 6 with Drive 2 (but it will physically alter partition 1)...
after drive 2/partition 1 has been "O" + "I" you need to make it a system/boot drive/partition by copying the DOS on it, enter H, then 2.

Once the dos files are copied you may also want to copy FDISK on this drive to access is easily from the harddrive (use C under the dos).

[Note: now you can also repeat step 6 with partitions P9 to P16 by associating them to D2 to D8 with the Edit disk sequence of FDISK... I won't describe it here since it's always the same thing]

8 - Before trying your new atari + harddrive you must then get the things back to the normal (P1->D1, P2->D2) so launch FDISK.COM enter:
and here associate D1 to P1, and D2 to P2. Save your changes by entering 2 and exit FDISK.

You can now switch off your computer...


9 - set SIO2IDE jumpers

Jumper Setting Description
HD1_ZW Off Disk D1: Off
INIT_ZW On Disk swap D1<=>D2
MS_ZW On Master mode


10 - Detach your 1050 disk drive, switch on the computer and wait for Atari and HDD power-up...
The computer will then start in basic mode and only the PWR_LED on the SIO2IDE is active
From the Atari BASIC prompt type BYE command, you will then see the self test screen
Press RESET key to restart the computer and load the DOS from the SIO2IDE disk (D1:)
You should now have the DOS screen (if you still have basic type DOS and if no result check taht you've followed the steps carefully)... Once at the dos prompt, you can run FDISK.COM to change your configuration and access other partitions...

[Note: if you want an automatic system start without to start in basic and then pressing Reset you must connect the Reset_Out signal (SIO_IO pin 4) as shown in the schematics in the Polish Technical Manual...]



Here you are. Enjoy...

> Postface

having a harddrive is cool but you would prefer to have your partitions full of games and utilities. There are 3 ways of doing that:

  • copy the files on floppies with your PC (special equipment needed I will explain this method soon)
  • use SIO2PC. That would be really the best choice since all the files are on your PC and it's pretty fast and easy...
  • in fact the third way is not really a third option. Either way 1 or 2 is long, so forget sio2ide 1.0 and upgrade to sio2ide 3.0. It's not the same software, it's not the same interface (the chip is not the same and some mods have to be done on the interface) but with the 3.0 version here is what you have:

    ATARI side:

    • uses standard Atari SIO at a speed of 19200 baud
    • emulates Atari disks D1: to D7:
    • can be used with any Atari DOS and OS
    • can be used without any problems with other SIO devices (disk drivers, printers, modems, SIO2PC, second SIO2IDE etc)
    • can be easy installed inside your Atari with 2.5' laptop HD
    • is easy to configure via special utility software (changing disks sequence and active directory)


      IDE device side:

    • all IDE ATA/ATAPI devices can be used: Disk Drives (2.5' and 3.5'), CD-ROMs, Compact Flash cards etc.
    • supports PC file systems, FAT16 and FAT32
    • supports CD file system, ISO9660
    • supports ATR disk images (SD, DD up to 16MB)
    • supports directory change (multiconfig)
    • is easy to configure, many text configuration files (sio2ide.cfg) can be stored in different directories
    • disk configuration can be checked by special checkfs.exe PC utility
    • standard disk utilities can be used (defrag.exe, scandisk.exe etc)

Let's also add that you can format your harddrive on your PC, and you can also create your directories with all your atari programs (such as ATR DD 16mo for example) from your PC. Once done you just have to put back the harddrive in your atari 130xe.


Article written by Romual Liné <>

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