This page addresses typical questions on HDDRIVER and also provides general information on mass storage devices and the Atari.

Installation and Partitioning
Do I lose any data when switching to HDDRIVER from another driver?
No, all existing data remain unchanged when installing HDDRIVER. Drives with more than four partitions created by old versions of the ICD driver software, which was using a non-standard partitioning scheme, require a special treament. In this case data have to be converted with software that is included in the HDDRIVER distribution. No data are lost by this conversion.
When installing HDDRIVER another already installed hard disk driver will automatically be disabled.
Are the partitions created by HDDRUTIL compatible with other drivers?
Yes, they are, because the partitioning scheme created by HDDRUTIL is fully AHDI compatible. This is not only the case for pure TOS compatible partitions, but also for TOS/Windows compatible partitions. Pure Windows compatible partitions are compatible with all platforms/drivers which support Windows compatible partitions.
Why does HDDRIVER only detect four partitions even though there are more?
Quite likely the drive was partitioned with a not fully AHDI compatible software, e.g. with a very old version of the ICD software. HDDRIVER includes software that without losing data converts the ICD format to the AHDI format, which is the standard for Ataris.
Do I need to re-configure HDDRIVER after updating to a new version?
No, when installing an update of HDDRIVER the settings of the previous version are automatically applied to the updated version.
How much RAM do HDDRIVER and HDDRUTIL need?
This depends on the size of the biggest partition, the cache settings and the settings for removable media. Configured for minimum memory usage, without support for the SCSI Driver target interface, and depending on the partition sizes HDDRIVER allocates about 25-100 KiB RAM. HDDRUTIL requires an Atari with at least 1 MiB of RAM.
What is the maximum drive/memory card capacity supported by HDDRIVER?
On any interface HDDRIVER supports devices and memory cards with a capacity of up to 1 EiB (Exbibyte). Drives > 2 TiB cannot be used by TOS, MagiC or MiNT with their full capacity, though, because these systems only support 32 bit sector numbers. Tools like HDDRUTIL or DISKUS, which support 64 bit sector numbers, can access sectors beyond the 2 TiB limit by using the SCSI Driver integrated in HDDRIVER. In order to use the full capacity of media > 1 GiB with the ACSI bus a suitable host adapter (ICD compatible), suitable card readers (GigaFile or UltraSatan) or emulations like SCSI2Pi are required.
What is the maximum partition size supported by HDDRIVER?
For each version of TOS HDDRIVER supports the respective maximum partition size. TOS 1.00-1.02 supports partitions of up to 256 MiB, TOS 1.04-3.06 of up to 512 MiB, TOS 4.0x of up to 1 GiB. These sizes are also valid for boot partitions and TOS/Windows compatible partitions. With MagiC or Big-DOS the non-boot partition size can be up to 2 GiB. In addition MiNT and MagiC support filesystems (FAT32/ext2) that do not have any relevant size limits.
HDDRUTIL displays the maximum FAT16 partition size supported by the current operating system with "System Limits".
How many drives/partitions does HDDRIVER support?
All TOS versions support up to 16 BIOS drives (A:-P:). With HDDRIVER partitions can also be assigned to the drives A: and B:. With MagiC HDDRIVER supports up to 25 drives (A:-Z: except U:), with MiNT or Big-DOS up to 31 drives (1:-6: and A:-Z: except U:).
HDDRUTIL displays the maximum number of drives supported by the current operating system with "System Limits".
Do drives/memory cards have to be formatted before partitioning?
No, formatting is only required for drives/memory cards with bad sectors. In all other cases it is a waste of time. Modern SATA drives do not support formatting anymore.
How can I store data on DVD-RAM, DVD+RW or BD-RE media with HDDRIVER?
In order to use these media with a regular TOS filesystem "Manage Multimedia Drives" in the "Removable Media/Memory Cards" settings has to be enabled. With this option HDDRIVER also manages multimedia drives, and you can partition them and use them for storing data.
Does HDDRIVER belong into the AUTO folder?
Usually not, because HDDRUTIL installs HDDRIVER as HDDRIVER.SYS in the root directory of the boot partition selected during the driver installation.
Only software emulators, where the system is not booted from a drive image but from a emulated GEMDOS drive, require HDDRIVER.PRG in the AUTO folder of this drive.
Does HDDRIVER require AUTO folder programs like FOLDRxxx, CACHExxx, JARxxx or SCSIDRV?
No, with HDDRIVER these programs are not needed because their functionality is already built-in. HDDRIVER can be configured with the respective settings instead.
Can HDDRIVER be installed on a different drive than C:?
Yes, as long as the boot partition is a so called primary partition. These are marked with a dot in the drive window of HDDRUTIL. TOS boots the hard disk driver from the first bootable partition. It can be located on a drive with any ACSI/SCSI ID or with IDE ID 0. If required TOS checks all drives on all supported interfaces: first IDE, then SCSI, then ACSI.
Can accessories be loaded from a different drive than C:?
Yes, because TOS automatically loads accessories from the boot drive when there are no ACCs on drive C:. If there are any ACCs on drive C:, though, they are always loaded from there. This is a feature of TOS, not of HDDRIVER.
HDDRIVER supports several ways of selecting the boot drive.
Why are my HDDRIVER modules not executed?
HDDRIVER must be re-installed after enabling the modules option in HDDRUTIL. The same applies after changing the TT-RAM option.
Hardware Support
Does HDDRIVER support memory cards?
Yes, memory cards are fully supported by HDDRIVER. Note that for memory cards the settings for removable media are relevant, except for CF cards in True IDE mode.
Does HDDRIVER support Atari SH and Megafile drives?
Drives of the Megafile series are supported. SH drives usually also work, but this should be tested with the respective drive and the HDDRIVER demo version.
Does HDDRIVER support any SCSI drive?
Any Single Ended SCSI drive (but no LVD SCSI drives) can be used with the TT's or Falcon's SCSI bus. Drives with a bus width of 16 bit (e.g drives with an SCA connector) require a customary adapter that reduces the bus width to 8 bit.
Which hardware supports drives/memory cards > 1 GiB with the ACSI bus?
SCSI drives > 1 GiB connected to the ACSI bus require special hardware in order to make use of the full drive capacity. Suitable hardware are the adapters by Inventronik, the GigaFile, the UltraSatan, the ICD Link and the LINK96/97. (This list may not be complete.)
HDDRIVER does not detect a SCSI drive connected to the ST/STE.
ST and STE do not have a real SCSI bus but only Atari's proprietary ACSI bus. Certain devices (those that require the so-called initiator identification) connected to this bus can only be used with the LINK96/97 host adapters or the adapters by Inventronik. Additionally, when using other adapters it may be required to switch off the drive's parity checking.
HDDRIVER/HDDRUTIL find a non-existent IDE port.
Some hardware extensions allocate the same addresses as the IDE ports, so that the device check might find a non-existent IDE interface. In this case with "Devices and Partitions" no IDE devices should not be configured for the affected ports.
Does HDDRIVER support SATA devices?
Yes, with a standard IDE-to-SATA adapter SATA hard drives/SSDs or optical SATA devices like DVD/BD drives can be can be used with HDDRIVER.
Does HDDRIVER support IDE or SATA devices at the SCSI bus?
Yes, with an Acard AEC-7720U SCSI-to-IDE bridge IDE and SATA (with an additional IDE-to-SATA adapter) drives have been successfully used with the SCSI bus. How well this works might also depend on the drive and adapter.
What has to be considered with the UltraSatan?
Due to incompatibilities with the SCSI standard in old UltraSatan firmwares using firmware version 1.20 or newer is required. Also note that the UltraSatan ignores the write protection switch setting.
Just like for any device with removable media, for the UltraSatan the settings for removable media, which can be configured with HDDRUTIL, are relevant.
What has to be considered with the GigaFile?
GigaFile revisions older than R08 cannot access the last sector of an SD card if the GigaFile is connected to the SCSI bus. Thus HDDRUTIL reports an error when partitioning because the root sector backup cannot be written. There is no issue with the ACSI bus.
Just like for any device with removable media, for the GigaFile the settings for removable media, which can be configured with HDDRUTIL, are relevant.
Each time when booting HDDRIVER reports a different ID for an IDE/ATAPI/SATA drive.
IDE and ATAPI devices connected to the Atari should not be operated in the Cable Select mode, but should be explicitly jumpered either as master or slave drive.
Are there any limitations when booting from ACSI?
With drives connected to the ACSI bus the boot partition has to be located within the first Gigabyte of a drive. Further, TOS can only boot from the ACSI bus when HDDRIVER is not loaded into TT-RAM.
Are there any limitations when booting from IDE?
TOS can only boot from a drive connected as master drive to the first IDE port if the drive was partitioned while being connected to the Atari's IDE port. This is caused by the wiring of the Atari's IDE port not having the same byte order used by other platforms for IDE. The Suska board uses the same IDE byte order as other platforms and does not have this limitation.
With IDE/SATA drives the boot partition has to be located within the first 32 Gigabytes of a drive. Further, TOS cannot boot from 4KN SATA drives, which have 4096 physical bytes per sector.
Why are SCSI transfers on Falcons with Alternate RAM a bit slower sometimes?
Direct SCSI transfers to/from Alternate RAM are not possible and a buffer with a fixed size has to be used. According to the SCSI Driver specification this limits the maximum number of bytes per SCSI transfer for the regular RAM as well, because this is a limit per bus.
Is HDDRIVER prepared for hardware interfaces like USB?
Yes, HDDRIVER and HDDRUTIL support any hardware interface for which a SCSI Driver is available. Developers of new interfaces just need to provide a SCSI Driver for their hardware, in the ideal case as an HDDRIVER module. See the SCSI Driver page for a list of available SCSI Drivers.
HDDRIVER itself provides integrated SCSI Drivers for Atari ACSI, Atari SCSI and Atari/Milan IDE/ATAPI/SATA.
Data Exchange
Does HDDRIVER support exchanging data with PCs and Macs?
Yes, with TOS/Windows compatible partitions data can easily be exchanged without any additional software with Windows (Windows XP and newer), Linux and macOS. Both FAT16 and FAT32 partitions (the latter only with MagiC or MiNT) can be used for the data exchange.
TOS/Windows compatible media do not work with Windows or macOS.
The media may have been created with the wrong physical drive parameters or with the wrong byte order. Manually adjusting these parameters when partitioning may help.
Why does Windows find only one partition on a removable medium even though there are several?
This is a limitation of old Windows versions: On drives Windows considers removable (this also applies to memory cards) only a single partition is supported. Windows 10 does not have this restriction anymore, as can be seen on the data exchange page.
Why can big TOS partitions not be mounted under Linux?
The maximum logical sector size supported by Linux is 4096 bytes. TOS partitions compatible with TOS 1.00/1.02 and bigger than 128 MiB, and TOS partitions compatible with TOS 1.04 or newer and bigger than 256 MiB have logical sectors bigger than 4096 bytes. Under Linux these partitions can only be used with mtools. TOS/Windows compatible partitions of the same size have smaller logical sectors and can be mounted as Windows partitions.
Can TOS boot HDDRIVER from a TOS/Windows compatible medium?
Yes, provided that the medium is not byteswapped. TOS/Windows compatible media used with the Atari's IDE interface have to be byteswapped, i. e. TOS cannot boot from them. One can boot, though, from TOS/Windows compatible media used with the ACSI or SCSI bus, because no byteswapping is required for these buses.
Therefore, for instance, with UltraSatan, GigaFile, SCSI2Pi or BlueSCSI HDDRIVER can be booted from TOS/Windows compatible memory cards.
Does the internal host adapter of the MegaSTE support more than one device?
Yes, with SCSI2Pi up to 8 emulated devices are possible. When it is about physical devices only a single device is supported.
Are Atari computers restricted to only use certain SCSI commands?
No, there are no restrictions for TT, Falcon and for STs with an ICD compatible host adapter. Any SCSI command can be used, not just those defined in the SCSI-2 specification. HDDRIVER, HDDRUTIL and the SCSI Driver Test Tool make use of READ/WRITE16, GET CONFIGURATION and REPORT LUNS, for instance.
What do SCSI "initiator identification" and "bus arbitration" mean?
Initiator identification means that a computer uses its own unique SCSI ID when communicating with a device. Without initiator identification some devices do not work properly or do not even respond. Bus arbitration depends on initiator IDs and ensures a proper SCSI bus handling when there is more than one computer (initiator) on the same bus.
With TT and Falcon SCSI initiator identification and bus arbitration is controlled by software and HDDRIVER supports it. With ACSI bus arbitration is not possible, but the LINK96/97 and the host adapter by Inventronik provide initiator identification by hardware.
What is wrong if the same SCSI device is reported for all SCSI IDs?
This happens when the computer's SCSI ID is identical with the SCSI ID of one of the connected devices. Ensure that the SCSI ID of your TT or Falcon is unique. The computer's SCSI ID should be the highest SCSI ID on the bus, i.e. 7 if only one computer is connected to the bus.
The SCSI ID setting only has an effect when a driver like HDDRIVER with SCSI initiator ID support is used. TT, Falcon and Milan store their SCSI ID in the NVRAM.
Are the transfer rates of memory cards higher than those of IDE/SATA hard drives?
No, usually not. Most memory cards do not support the IDE transfer mode READ/WRITE MULTIPLE. Only some Industrial Grade cards offer this mode. IDE hard drives usually provide higher transfer rates than memory cards, even though they have longer access times. These differences are easily measurable with Atari computers.
Is there anything to consider when using HDDRIVER with Cubase Audio?
Cubase Audio does not handle the Falcon's SCSI bus in compliance with the SCSI standard, which can lead to issues with HDDRIVER 8 and newer. If the CAFFIX software, which is included in the HDDRIVER distribution, cannot put things right, the only work-around is using the last version 7.93 of the HDDRIVER 7 series. This version lacks many features of current versions, requires more memory and is less performant, but it is known to work with Cubase. Most functions of the current HDDRUTIL can also be used with HDDRIVER 7.93, by the way.
Users of newer versions of HDDRIVER can request HDDRIVER 7.93 for free by e-mail, but should verify first whether with their hardware there are actually issues with the current HDDRIVER and Cubase.
Can I use HDDRUTIL with a different driver than HDDRIVER?
Yes, because many functions of HDDRUTIL only require SCSI Driver or XHDI support. Any driver that provides a correct implementation of these open software interfaces is fine for running HDDRUTIL. This is the case for any type of hardware interface.