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The SCSI Hard Drive Emulator for retro computing.




  1. downloads for v3/v4/v5 hardware revisions.
  2. downloads for v6 hardware revisions. This firmware will NOT work on the older boards.


[7 October 2016]v6.0.13 Bugfix release

  • Added glitch filter to SCSI signals
  • Restored parity-checking option (defaults to disabled)

[12 September 2016]v6.0.10 Bugfix release

  • Fixed issue with some UHS-1 SD cards.
  • Fixed SCSI corruption issues

[27 August 2016]v6.0.8 Synchronous transfers

  • Fixed "SCSI2SD config protocol error" when saving config settings to the SD card.
  • Fixed USB storage with 3 or more devices configured
  • Added support for synchronous transfers up to 10MB/s

[14 August 2016]v6.0.6 Performance improvements

  • Fixed performance bugs, especially for write performance. Sync transfers coming soon...

[14 August 2016]v6.0.5 First non-BETA V6 firmware

  • Fixed more SCSI bugs. The firmware should work on most systems now, excluding an issue on some Amiga machines.
  • Added firmware update support to scsi2sd-util6. See the updated Quickstart guide for instructions.

[16 July 2016]v6.0-BETA3 Fixed V6 firmware

  • Fixed critical SCSI bug. There was a silly bug that prevented the previous v6 firmwares from working on most systems.

Apologies for the delay in finally fixing this bug and getting the firmware stable. The v6 boards will leave BETA status now as soon as the scsi2sd-util6 utility supports firmware updates on all platforms. Performance improvements (ie. 10MB/s synchronous support) will be done after firmware upgrade is fixed.
Early adopters should update the firmware using dfu-util on Linux or STM DfuSe on Windows. Remember to put a shunt on the pins labelled "BOOTLDR" and reconnect the USB cable to enter bootloader mode.

[16 June 2016]v6.0-BETA2 New V6 firmware

  • Fixed SD card compatibility issues
  • Fixed SCSI compatibility issues
  • Added SD card hotswap support
  • Performance improvements

[17 May 2016] Sneak-peak at the new V6 boards
SCSI2SD V6 will go on sale from 28th May with BETA quality firmware. This is a completely new hardware design which adds commonly requested features.
The V5 boards will remain available for the foreseeable future. Most people should continue to buy the older V5 board ! The V6 boards are more expensive to produce, and most people don't require the additional functionality.

  • Full-Size SD slot. This makes it much easier to develop faceplates for external access. I am currently prototyping a matching 3.5" bracket with faceplate.
  • A floppy-style berg power connector is used instead of the traditional Molex plug. This reduces the width of the device, simplifying 3.5" bracket production. Most systems can self-power the board and don't need a separate power cable anyway.
  • Better performance. The hardware supports synchronous transfers at 10MB/s.
  • Access to the data via USB. The SCSI2SD drives will appear when connected to a PC via USB. This is limited to around 1.2MB/s (USB FS speeds).
  • Superior noise resistance to deal with poor termination and poor cabling.
  • Integrated terminator, now enabled via software configuration

Initial BETA firmware limitations:

  • No hot-swap support
  • Inconsistent performance due to immature firmware. The boards may not perform any better than the V5 boards until the software is improved to make use of the faster hardware.
  • Cost and supply limitations. I only have a small number (50) of V6 boards available in the first batch, and priced at $125 AUD.

[12 January 2016]v4.6 New firmware

  • Fixed bug when using sector size that isn't a multiple of 4 (eg. 522 bytes)
  • Fixed a bug that caused hanging or scsi phase errors on high speed scsi hosts.
  • Fixed a hang when processing a SCSI RESET in a data phase.
  • scsi2sd-util: Fixed USB connection problems under Windows 10.
  • Added option to treat luns as separate devices
  • Improved boot up time. It is now possible to replace the bootloader with a version that doesn't pause for 2 seconds (bootloader). This is required on some Amigas and the Staubli JC5. Replacing the bootloader CAN BRICK YOUR DEVICE if it fails half-way, so do not attempt this unless necessary.

SCSI2SD Archived News


Traditional hard drives last 5 years*. Maybe, if you're luckly, you'll get 10 years of service from a particular drive. The lubricants wear out, the spindles rust. SCSI2SD is a modern replacement for failed drives. It allows the use of vintage computer hardware long after their mechanical drives fail. The use of micro-SD memory cards solves the problem of transferring data between the vintage computer and a modern PC (who still has access to a working floppy drive ?)

*All statistics are made up.


The new V6 board and 2.5" PowerBook version are available at:

The 3.5" boards are available from the following distributors:

3rd party accessories

  • Internal faceplates for V5 and V6 boards, and external V5 case.
  • Thingiverse nibblernibbles has created a 3d-printable external enclosure for the SCSI2SD + DB25 adapter. Power can be supplied over USB for hosts which don't supply termination power.
  • SCSI2SD V5 & V6 Bracket by Maya Designs


  1. In-built active terminator.
  2. Emulates up to 4 SCSI devices (7 for the V6 version)
  3. Supports sector sizes from 64 bytes to 8192 bytes
  4. Firmware updatable over USB
  5. Highly configurable over USB
    • Selectable SCSI ID
    • Selectable parity support
    • Enable/disable Unit Attention Condition
    • Artificial limits on the SCSI disk size (eg. limit size to 4G to avoid OS bugs)
    • Sector size (can also be set via the SCSI MODE SELECT command, as sent by SCSI format utilities).
  6. External LED connector.

Technical Specifications

V5 hardware V6 hardware
SCSI Interface SCSI-2 Narrow 8-bit 50-pin connector.

Supports asynchronous transfers only.

SCSI-2 Narrow 8-bit 50-pin connector.

FAST10 (10MB/s) synchronous transfers. Higher speeds to be supported with firmware update.

SD Card Interface microSD, tested up to 64GB

Communication is via the SPI protocol at 25MHz (3MB/s theoretical max)

Full-size SD, tested up to 32GB

Up to 20MB/s

USB Interface Firmware updates and configuration

USB 2.0 micro-B

Firmware updates, configuration, and mass-storage

USB 2.0 micro-B. Mass-storage at USB 2.0 FS speeds (1.2MB/s max)

Power 5V via standard Molex 4-pin drive connector, USB, or self-powered using the SCSI host termination power.

2.35W maximum (500mA)

DO NOT CONNECT 12V at all if you need to make your own power cable as it risks destroying the board if you accidentally swap the wires.

5V via floppy 4-pin drive connector, USB, or self-powered using the SCSI host termination power.

2.35W maximum (500mA)

Dimensions (L x W x H) 5cm x 10cm x 1.5cm 10cm x 9cm x 1.5cm

Tested under optimal conditions. For comparison, here are some benchmarks of some older SCSI hardware.

Up to 2.6MB/s read, 2.3MB/s write. Up to 10MB/s.

Known Issues

SD Card Known Issues

  • Samsung UHS-1 Speed-class 3 "Pro" and "Pro+" cards do not work. Other brands of UHS-I Speed-class 3 cards are OK. These very fast cards are overkill and not necessary as the SCSI2SD cannot transfer at UHS-I speeds.


Computer systems

  • Mac LC-III and LC-475
  • Mac II running System 6.0.8
  • Mac SE/30
  • Apple IIgs using Apple II High Speed SCSI controller card
  • Symbolics Lisp Machine XL1200, using 1280 byte sectors
  • PDP-11/73 running RSX11M+ V4.6
  • Microvax 3100 Model 80 running VMS 7.3
  • Commodore Amiga 500+ with GVP A530
  • Commodore Amiga 500 KS 1.3 with Oktagon 508 SCSI-2 controller
  • Amiga 2000 (B2000 rev 6.4 ECS) with DKB RapidFire SCSI 1 card
    • May require bootloader replacement if it only starts up while on USB power.
  • Amiga 3000
    • May require bootloader replacement if it only starts up while on USB power.
  • Amiga 4000 equipped with CyberStorm PPC using 68pin adapter.
  • Atari TT030 System V
  • Atari TT running TOS 3.06 with HDDRIVER software version 9.06
  • Atari Mega ST 1; TOS 1.04; Protar ProFile 30 external hard drive enclosure (1GB size limitation)
  • Atari MEGA STE
    • needs J3 TERMPWR jumper
    • 1GB limit (--blocks=2048000). The OS will fail to read the boot sector if the disk is >= 1GB.
  • Atari Falcon, TOS 4.02, HDDRIVER 9.06 driver
  • Sharp X68000
    • SASI models supported. See for information on building a custom cable.
    • needs J3 TERMPWR jumper
    • Set to SCSI ID 3. ID0 will not work.
  • Compaq XP-1000 Professional Workstation
    • Alpha 21264 CPU, 667MHz, with a QLogic SCSI controller in a PCI slot
  • SCSI-based Macintosh Powerbooks (2.5" SCSI2SD)
  • AT&T 3B2/600
  • Sun 2/120 Workstation (Unit Attention disabled)
  • Sun 4/50 workstation
  • Data General MV/2500DC running AOS/VS
    • Requires changing deviceTypeModifier to 0x4c in XML config file. Configurable deviceTypeModifier is supported from firmware v4.3.
  • Applix 1616
  • IMS MM/1
  • NeXTcube + NeXTSTEP 3.3
  • NeXTStation
    • Modified geometry settings are required to avoid "cylinder group too large" errors while formatting. Configurable geometry is supported from firmware v4.3
  • Apollo 400/425s running DOMAIN/OS
  • Motorola System V/68 R3V7 and R3V8.
    • Since the installation have information about limited number of drives(most of them with custom commands) it requires a pre-installed disk image to be dd-ed on it. Works with MVME167 and MVME177
  • Motorola System V/88 R40V4.0 through R40V4.4
  • BBC micro/Master with Akhter host adapter
  • Sun SparcStation 2 w/ Solaris 2.5.1
  • Solbourne S3000
  • TI-99/4A
  • Myarc Geneve 9640
  • SGI Indy
  • RM Nimbus


  • Roland JS-30 Sampler
  • Roland W-30
  • Roland VS2480
  • Roland S-760, S-770
  • Roland XV-5080
  • Akai S950
  • Akai S1000, S2000, S3200, S3000XL, MPC 2000XL, DPS 12
    • SCSI cable reversed on S3200
    • There are compatibility problems with the Akai MPC3000. It works with the alternate Vailixi 3.5 OS with multi-sector transfers disabled.
    • MPC3000 example video
  • AKAI S5000 and S6000 with Firmware Version 2.14
  • EMU Emulator E4X with EOS 3.00b and E6400 (classic) with Eos 4.01
  • EMU E6400 w/ EOS2.80f
  • EMU Emax1, Emax 2
    • E-Mu Emax video
    • Emax 2 video
    • To boot the emax you will need to use the internal scsi connection, rear db25 does not support scsi boot
    • Set SCSI2SD "Selection Delay" parameter to 1ms
  • EMU Darwin 8ch hard disk recorder
  • Emu ESI2000, ESI4000
  • Ensoniq ASR-X, ASR-10 (from v3.4, 2GB size limit)
  • Ensoniq EPS16+
  • Kurzweil K2000R
    • See for size limits which a dependant on the OS version. Older OS versions have a 1GB limit.
    • SCSI cable reversed
  • Kurzweil K2500XS
  • Casio FZ-20M
    • Requires TERMPWR jumper. The manual shows the pin25 of the DB25 connector is "not connected".
    • May require scsi2sd-config --apple flag
  • Yamaha A5000, A3000, EX5, EX5R, RS7000
  • EMU ESI4000 [1] [2]
  • Synclavier 9600.
    • Disable Parity. Max size == 9GB.
  • Waveframe 1000
    • Max size = 16GB
  • Sequential Circuits Studio 440. [3]
    • Max size = 1GB



Firmware update utility and configuration tool at:

  1. downloads for v3/v4/v5.
  2. downloads for v6.

These files are currently available for Windows, Linux, and Mac OSX.

A copy of all sources can be obtained via the command:

git clone --recursive git://

or (for V6)

git clone --recursive git://

Alternatively, the git sources can be viewed using your web browser by clicking here or here (V6)


Alternative Open SCSI Projects

  • AJ's alternative implementation. AJ and I originally had a competition to design and build a SCSI device to boot an old Mac LCIII. The deadline for that competition has long-since expired without a winner, but we have both continued to progress our designs.
  • S2I (was: SCSI2IDE)
  • AVR based SCSI RAM disk


For historical project information see SCSI2SD old

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