shadoooo said
> Hello,
> I'm a decent collector of big iron, aka mini computers, mainly DEC and DG.
> I'm often facing common problems with storage devices, magnetic discs and 
> tapes are a little prone to give headaches after years, and replacement 
> drives/media in case of a severe failure are unobtainable.
> In some cases, the ability to make a dump of the media, also without a 
> running computer is very important.
> Whence the idea: realize an universal device, with several input/output 
> interfaces, which could be used both as storage emulator, to run a computer 
> without real storage, and as controller emulator, to read/write a media 
> without a running computer.
> To reduce costs as much as possible, and to allow the better compatibility, 
> the main board shall host enough electrical interfaces to support a large 
> number of disc standard interfaces, ideally by exchanging only a personality 
> adapter for each specific interface, i.e. connectors and few
> There are several orders of problems:
> - electrical signals, number and type (most disk employ 5V TTL or 3.3V TTL, 
> some interfaces use differential mode for some faster signals?)
> - logical implementation: several electrical signals are used for a specific 
> interface. These must be handled with correct timings
> - software implementation: the universal device shall be able to switch 
> between interface modes and be controlled by a remote PC
> I suppose the only way to obtain this is to employ an FPGA for logic 
> implementation of the interface, and a microprocessor running Linux to handle 
> software management, data interchange to external (via Ethernet). This means 
> a Xilinx Zynq module for instance.
> I know there are several ready devices based on cheaper microcontrollers, but 
> I'm sure these can't support fast and tight timing required by hard disk 
> interfaces (SMD-E runs at 24MHz).
> The main board should include a large enough array of bidirectional 
> transceivers, possibly with variable voltage, to support as much interfaces 
> as possible, namely at least Shugart floppy, ST506 MFM/RLL, ESDI, SMD, IDE, 
> SCSI1, DEC DSSI, DEC RX01/02, DG6030, and so on, to give a starting point.
> The common factor determining what kind of disc interface can be support on 
> hardware side is obviously the type of transceiver employed, for instance a 
> SATA would require a differential serial channel, which could not be 
> available.
> But most old electronic is based on TTL/CMOS 5V logic, so a large variety of 
> computer generations should be doable.
> For the first phase, I would ask you to contribute with a list of interfaces 
> which could be interesting to emulate, specially if these are similar to one 
> from my list.
> I please submitters to send me by email or by web link when possible, 
> detailed documentation about the interface they propose, so I can check if it 
> could be doable and what kind of electrical signals are needed.
> Also detailed information about interfaced I listed is appreciated, as could 
> give some detail I'm missing.

The Diablo / Pertec interface was a popular industry standard. Here's a product 
(no connection) that implements it
It would be great if there were open source or cheaper devices, maybe there 
are, I guess the Unibone can do this? (I don't have one yet)

(btw I never actually subscribed to cctech but somehow my cctalk ones get 
echoed over there)

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