The SCSI Driver is an open software interface for accessing any kind of peripheral, not only SCSI devices. Also SATA drives for optical media like DVDs and BDs use the SCSI command set. For other hardware interfaces, e.g. IDE or USB, SCSI commands can be emulated, like HDDRIVER does it for IDE and SATA hard drives. All in all with SCSI Drivers one can send any SCSI command to any interface.
The sources of the software on this page are available on GitHub.
HDDRIVER fully supports the current version 1.01 of the SCSI Driver interface. The documentation is available in ST GUIDE format and includes C and Modula-2 bindings.
A minor weak point of the SCSI Driver interface is the limitation to 8 LUNs (SCSI sub-units) per device, even though SCSI (but not ACSI) permits 32 LUNs. With PiSCSI you can easily create devices with more than 8 LUNs. With a small, backwards compatible extension for the SCSI Driver interface since HDDRIVER 12 you can use all 32 LUNs.
HDDRIVER is the only driver that supports the target interface: TT or Falcon are detected as SCSI devices by other computers (also non-Ataris) and can execute standardized or customized SCSI commands.
The screenshot displays the device check of a TT, with a Falcon on the same bus. The TT (SCSI ID 7) is running HDDRIVER 11.06, the Falcon (SCSI ID 6) is running HDDRIVER 11.05. Both computers "see" each other, and one can execute SCSI commands sent by the other.
Sample code in C for implementing custom SCSI commands is provided on GitHub. In order for the target interface to work faultlessly any software accessing SCSI peripherals has to use the SCSI Driver interface.
In the HDDRUTIL settings you can configure whether HDDRIVER shall be installed with or without target interface support. Without target support (the standard interface remains available) HDDRIVER allocates about 3 KiB less RAM.
Fully functional SCSI Drivers are available for the following hardware interfaces and emulators:
| Interface/Emulator | Software Package | Author |
|---|---|---|
| Atari ACSI/SCSI/IDE | HDDRIVER CBHD/SCSIDRV.PRG |
Uwe Seimet Claus Brod, Steffen Engel |
| Atari ATAPI/SATA | HDDRIVER | Uwe Seimet |
| Milan IDE/ATAPI/SATA | HDDRIVER | Uwe Seimet |
| Milan SCSI | Milan PCI SCSI Driver | Michael Schwingen |
| MagiCMac | CBHD/MM_SCSI.PRG | Steffen Engel, Thomas Tempelmann |
| MagiCPC | CBHD/SCSIDRIV.DLL | Steffen Engel |
| Hatari 2.x (Linux SCSI/IDE/ATAPI/SATA/USB) | NF_SCSI, see below | Uwe Seimet |
| ARAnyM 1.1 (Linux SCSI/IDE/ATAPI/SATA/USB) | NF_SCSI, see below | Uwe Seimet, Thorsten Otto |
There are also other, potentially incomplete implementations with unknown status (e.g. for USB), which are not listed here. Unfortunately the SCSI Driver of the FireBee has known bugs and thus cannot be used by HDDRIVER and HDDRUTIL.
When implementing a new SCSI Driver it is recommended to not only read the SCSI Driver specification but also the official SCSI standards. Information on the SCSI Driver interface is also provided by some of my papers for the German ST Computer magazine.
This SCSI Driver for TOS with Linux provides direct access to devices like hard disks, SSDs, memory cards, optical drives or streamers. Supported interfaces are SCSI, IDE/SATA and USB. NVMe SSDs require an NVMe-to-USB adapter.
The driver can be launched as a regular program or as an HDDRIVER module. With Hatari the NatFeats support has to be explicitly enabled in the Hatari configuration file or on the command line.
SCSI_MON logs SCSI Driver calls, which helps to analyze errors or when implementing a new SCSI Driver. SCSI_MON also helps to understand the SCSI and SATA software protocols. The program can be launched as a regular program or as an HDDRIVER module.
SCSI Driver and Firmware Testsuite 2.33
This archive contains tools for testing SCSI firmware/emulations (in particular SCSI-2 and newer) and certain SCSI Driver functions, also for SCSI Drivers that support IDE/SATA drives or USB devices.
The sample logfile shows the data of devices passing all tests: An IBM DDRS-39130 hard drive, a hard drive emulated by PiSCSI and the target interface of HDDRIVER.