BlueSCSI-v2/lib/SCSI2SD

SCSI2SD, The SCSI Hard Drive Emulator for retro computing.

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
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.


Features

In-built active terminator.
Can optional supply terminator power back to the SCSI bus
Emulates a non-removable hard drive for maximum compatibility.
Supports sector sizes from 64 bytes to 2048 bytes
Firmware updatable over USB
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).


Technical Specifications

SCSI Interface
SCSI-2 Narrow 8-bit 50-pin connector. Supports asynchronous transfers only.
SD Card Interface
Standard SDSC (1GB maximum size)
SDHC (32GB maximum size)
SDXC cards are untested. Donations welcome.
Communication is via the SPI protocol at 25MHz.
Power
5V via standard molex drive connector.
Dimensions
10cm x 10cm x 1.5cm
A 3D-printable bracket is in testing to suit a standard 3.5" hard disk bay.


Performance

As currently implemented:

Transfer size: 512 2048 8192 65536
-------------------------------------------------------
read: 2MB/s 2.1MB/s 2.5MB/s 2.6MB/s
write: 125kB/s 441kB/s 1.5MB/s 2.3MB/s
-------------------------------------------------------


Tested with a 16GB class 10 SD card, via the commands:

# WRITE TEST
sudo dd bs=${SIZE} count=100 if=/dev/zero of=/dev/sdX oflag=dsync

# READ TEST
sudo dd bs=${SIZE} count=100 if=/dev/sdX of=/dev/null

Compatibility

Desktop 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 (from v3.3)
Symbolics Lisp Machine XL1200, using 1280 byte sectors (from v3.4)
PDP-11/73 running RSX11M+ V4.6
Amiga 500+ with GVP A530
Atari TT030 System V

Samplers

Roland JS-30 Sampler
Akai S1000, S3200, S3000XL, MPC 2000XL, DPS 12
SCSI cable reversed on S3200
There are compatibility problems with the Akai MPC3000. It works (slowly) with the alternate Vailixi OS with multi-sector transfers disabled.
EMU Emulator E4X with EOS 3.00b and E6400 (classic) with Eos 4.01
Ensoniq ASR-X, ASR-10 (from v3.4, 2GB size limit)
ASR-20 Requires TERMPWR jumper.
Kurzweil K2000R
See kurzweil.com for size limits which a dependant on the OS version. Older OS versions have a 1GB limit.
SCSI cable reversed
Casio FZ-20M
Requires TERMPWR jumper. The manual shows the pin25 of the DB25 connector is "not connected".
May require scsi2sd-config --apple flag

Other

HP 16601A logic analyzer
Fluke 9100 series