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- 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.
- Firmware updatable over USB (TODO software not yet implemented)
- Highly configurable over USB (TODO software not yet implemented)
- 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)
- 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:
- Sequential read: 250kb/sec Sequential write: 240kb/sec
- Tested with a 16GB class 10 SD card, via the commands:
- # WRITE TEST
- sudo dd bs=8192 count=100 if=/dev/zero of=/dev/sdX oflag=dsync
- # READ TEST
- sudo dd bs=8192 count=100 if=/dev/sdX of=/dev/null
- I am working on updating the slow polling SD card communication to use DMA. I expect the performance to reach 1Mb/sec.
- Compatibility
- Tested with Linux (current), Apple Macintosh System 7.5.3 on LC-III, and LC-475
- hardware.
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