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64 lines
2.0 KiB
Plaintext
64 lines
2.0 KiB
Plaintext
SCSI2SD, The SCSI Hard Drive Emulator for retro computing.
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Traditional hard drives last 5 years*. Maybe, if you're luckly, you'll get 10
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years of service from a particular drive. The lubricants wear out, the spindles
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rust. SCSI2SD is a modern replacement for failed drives. It allows the use of
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vintage computer hardware long after their mechanical drives fail. The use of
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SD memory cards solves the problem of transferring data between the vintage
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computer and a modern PC (who still has access to a working floppy drive ?)
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*All statistics are made up.
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Features
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In-built active terminator.
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Can optional supply terminator power back to the SCSI bus
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Emulates a non-removable hard drive for maximum compatibility.
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Firmware updatable over USB (TODO software not yet implemented)
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Highly configurable over USB (TODO software not yet implemented)
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Selectable SCSI ID
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Selectable parity support
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Enable/disable Unit Attention Condition
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Artificial limits on the SCSI disk size (eg. limit size to 4G to avoid OS bugs)
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Technical Specifications
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SCSI Interface
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SCSI-2 Narrow 8-bit 50-pin connector. Supports asynchronous transfers only.
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SD Card Interface
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Standard SDSC (1GB maximum size)
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SDHC (32GB maximum size)
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SDXC cards are untested. Donations welcome.
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Communication is via the SPI protocol at 25MHz.
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Power
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5V via standard molex drive connector.
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Dimensions
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10cm x 10cm x 1.5cm
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A 3D-printable bracket is in testing to suit a standard 3.5" hard disk bay.
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Performance
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As currently implemented:
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Sequential read: 424kb/sec Sequential write: 414kb/sec
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Tested with a 16GB class 10 SD card, via the commands:
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# WRITE TEST
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sudo dd bs=8192 count=100 if=/dev/zero of=/dev/sdX oflag=dsync
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# READ TEST
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sudo dd bs=8192 count=100 if=/dev/sdX of=/dev/null
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I am working on updating the SD card communication to use DMA, to allow simultaneous use of the SD and SCSI interfaces. I expect the performance to reach 1Mb/sec.
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Compatibility
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Tested with Linux (current), Apple Macintosh System 7.5.3 on LC-III, and LC-475
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hardware.
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