Fix typo in scsi2sd-config Makefile for building on Mac OSX
[SCSI2SD.git] / readme.txt
1 SCSI2SD, The SCSI Hard Drive Emulator for retro computing.
2
3 Traditional hard drives last 5 years*. Maybe, if you're luckly, you'll get 10
4 years of service from a particular drive. The lubricants wear out, the spindles
5 rust. SCSI2SD is a modern replacement for failed drives. It allows the use of
6 vintage computer hardware long after their mechanical drives fail. The use of
7 SD memory cards solves the problem of transferring data between the vintage
8 computer and a modern PC (who still has access to a working floppy drive ?)
9
10 *All statistics are made up.
11
12
13 Features
14
15 In-built active terminator.
16 Can optional supply terminator power back to the SCSI bus
17 Emulates a non-removable hard drive for maximum compatibility.
18 Firmware updatable over USB
19 Highly configurable over USB
20 Selectable SCSI ID
21 Selectable parity support
22 Enable/disable Unit Attention Condition
23 Artificial limits on the SCSI disk size (eg. limit size to 4G to avoid OS bugs)
24
25
26 Technical Specifications
27
28 SCSI Interface
29 SCSI-2 Narrow 8-bit 50-pin connector. Supports asynchronous transfers only.
30 SD Card Interface
31 Standard SDSC (1GB maximum size)
32 SDHC (32GB maximum size)
33 SDXC cards are untested. Donations welcome.
34 Communication is via the SPI protocol at 25MHz.
35 Power
36 5V via standard molex drive connector.
37 Dimensions
38 10cm x 10cm x 1.5cm
39 A 3D-printable bracket is in testing to suit a standard 3.5" hard disk bay.
40
41
42 Performance
43
44 As currently implemented:
45
46 Sequential read: 424kb/sec Sequential write: 414kb/sec
47
48 Tested with a 16GB class 10 SD card, via the commands:
49
50 # WRITE TEST
51 sudo dd bs=8192 count=100 if=/dev/zero of=/dev/sdX oflag=dsync
52
53 # READ TEST
54 sudo dd bs=8192 count=100 if=/dev/sdX of=/dev/null
55
56 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.
57
58
59 Compatibility
60
61 Tested with Linux (current), Apple Macintosh System 7.5.3 on LC-III, and LC-475
62 hardware.
63