SCSI SD Card reader [Large picture warning]

[slaeshjag]

Hello!

So, for the past few weeks, I've been working with a friend on a SCSI SD card reader. This is intended to be a lower cost alternative to existing SCSI card readers, that are getting more and more rare. It will plug right into the DB25 socket, with the device having a male plug, removing the need for a SCSI cable. It will also have built in terminator. Storage will be an µSD/µSDHC.

Provided there's enough interest, the plan is to make this into an actual product. Can't be too specific about expected price as I have yet to speak with any distributors (although ED seemed interested in carrying it when I mentioned Amiga 3000 has a SCSI port...) However, price is a key goal, and I'd consider a retail price over €50 to be a failure. The manufacturing costs won't be anywhere near that though. Speaking of which, that's another thing not yet fully determined. We do have a preliminary BOM, but ofc, it's still early in development..

Current status: We just got a first prototype running. It's still a mess of wires on protoboard, but when this works, and shown interest is high enough, dev boards will be made. These will be used for CE EMC testing, and will be sent out to distributors for trial, apart from being used for polishing up the firmware. These will be as close as possible to production hardware.

It will come in a case.

As for the current protoype, it is currently capable of booting Mac OS8. It's not very fast yet (all code is a straight C implementation on a Cortex M0 µC...) Within the next few days, the read/write code will be rewritten as a tight assembler loop.

Theoretical max read/write speed is 3 MB/s. Aim is at somewhere between 2-3 MB. Currently, OS8 needs special software (requires Lido 7.56) to format the SD card.

Prototype pictures:

Testing will later be done on an Ensoniq ASR-10, and hopefully some amigas.

 

[Linux-SWAT]

Neat !

I also used to have a SCSI ensoniq, but used floppies only ^^.

 

[Wally]

Many WIRES!

 

[slaeshjag]

The ASR-10 is turning out to be a fun one, it has so far voilated the SCSI spec at three places already, and we still have some work to go.

 

[moxie]

This is so, so awesome!!! Tell me when you have something working for an AKAI s2000, and I'll buy it off you at once!

 

[slaeshjag]

We don't have access to any other sequencers. However, if we get to the devboard stage, we might be able to arrange something.

Speaking of sequencers, the ASR-10 just booted up from SD card.

 

[moxie]

"Verktygsdiskettavbilder" - Hahahaha!

 

[hedwards]

Why is it that the practicality of a project is usually inversely related to the awesomeness of the project?

Seriously, this is an awesome project, but I'm somewhat curious as to what use this is other than being awesome.

 

[Asiyura]

^^^ Keeping old hardware working by replacing with modern parts the old ones that are the most susceptible to die : hard disk.

 

[Grench]

In theory, with an old SCSI RAID controller you'd be able to do JBOD or arrays over up to 7 (single lane) or 15 (dual lane controller) SD cards simultaneously.  Just for giggles and grins.

You said you're running this over a DB25...  I thought old narrow SCSI required 50 pins and SCSI II fast-wide required 68?

http://en.wikipedia.org/wiki/SCSI

More research later...  It looks like the DB25 was an apple-fication of the SCSI standard.

http://en.wikipedia.org/wiki/SCSI_connector

Is there any chance of making these with straight-up 50pin ribbon cable attachments so they can connect directly to internal SCSI drive positions?

Also - are you going to have a SCSI termination resistor & switch built in?

Cool stuff.

 

[moxie]

The 25-pin connector was an appleification that was also adopted by a bunch of samplers and stuff. But unless I'm very mistaken, there really is no magic difference, so if you have a 25-pin version working then you'd have no trouble doing a 50-pin version - If I recall correctly, it's just a bunch of shielding/grounding wire that is gone.

 

[slaeshjag]

DB25 is used by a lot of old samplers and Apple computers. Amiga 3000 also used DB25.

It will be possible to connect it up with an adapter. We're currenly having some timing issues making most PC controllers hate us when connecting up via internal 50-pin, but we're working on it.

The DB25 version will have a built-in terminator, but due to the massive part count and cost increase in having it switchable, it'll always be on. We're investigating having the termination networks socketed though.

EDIT: Actually, I think I figured it out. We don't support the message out phase, and ignore the attention pin completely. Wrote some code that might be enough to make the host happy, but I won't be able to test for about two weeks as the friend I'm working on this with is away, and the prototype is at his place.

 

[slaeshjag]

Long time no post... Been a bit busy with other things. But, now we have a PCB-layout for the first pcb prototypes! Will order them and the parts this week hopefully.

 

[slaeshjag]

PCB:s ordered

 

[TrashyMG]

Wonders if this will work on the Mac Classic...

 

[slaeshjag]

It should. I'll test on my SE though when we get the boards if you're interested

 

[TrashyMG]

It should. I'll test on my SE though when we get the boards if you're interested

Cool, I have a working Mac Classic that just sits there.. Would be nice to have a more permanent storage than just floppies.

 

[moxie]

Take my money!!!

 

[moxie]

And a more serious post: If you'd like to have the board tested against music stuff like the AKAI S2000 sampler or the DPS12 hard disc recorder, I'd be happy to test things. I am, after all, within the reach of Posten

 

[slaeshjag]

I am sure that making it compatible with such devices will make it a lot more sellable. I'll let you know when we have a working prototype PCB that we don't need ourselfs.