SCSI2SD

The SCSI Hard Drive Emulator for retro computing.

News

3 Oct 2013:
Source code and PCB files <a href="http://www.codesrc.com/gitweb/index.cgi?p=SCSI2SD.git;a=summary">uploaded.</a>

10 Sep 2013:
It works! I have a working prototype that works well. There are a few minor errors in the PCB layout that will be fixed in the next revision.

Overview

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

1. In-built active terminator, enabled by a jumper.
2. Can optional supply terminator power back to the SCSI bus
3. Selectable SCSI ID
4. Emulates a non-removable hard drive for maximum compatibility.

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

Performance

As currently implemented:

Sequential read: 250kb/sec Sequential write: 50kb/sec

These numbers are dreadful. I am working on updating the slow polling SD card communication to use DMA. I expect the performance to reach 1.8Mb/sec.

Compatibility

Tested with Linux (current), Apple Macintosh System 7.5.3 on LC-III, and LC-475 hardware.

Howto

• FormatWithBasiliskII Format an SD card for use with Apple Macintosh hardware using the Basilisk II emulator

Old

For historical project information see SCSI2SD old