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bugsy_malone 666
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Rpi as a SCSI hard drive?

Tue Dec 02, 2014 4:14 pm

Ok so I have an old Amiga and just got an external harddrive addon for it (an A590 for those who are interested) which has a 25pin scsi connector on the back.

I need to transfer files that are bigger than the disks the amiga normally uses and thought what I really need is a scsi drive to bung them on. Well this isnt happening as scsi drives are kind of rare for what I need.

So then I though, would an Rpi be able to pretend to be a Scsi hard drive? Its got loads of GPIO pins and I am sure there must be a method to do scsi to usb.

I just want to back up the stuff on this HD before I format it to remove some of the bad blocks on the drive and start afresh (on a whopping 20mb drive!)

Any ideas much appreciated :)

fruitoftheloom
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Re: Rpi as a SCSI hard drive?

Tue Dec 02, 2014 6:16 pm

bugsy_malone 666 wrote:Ok so I have an old Amiga and just got an external harddrive addon for it (an A590 for those who are interested) which has a 25pin scsi connector on the back.

I need to transfer files that are bigger than the disks the amiga normally uses and thought what I really need is a scsi drive to bung them on. Well this isnt happening as scsi drives are kind of rare for what I need.

So then I though, would an Rpi be able to pretend to be a Scsi hard drive? Its got loads of GPIO pins and I am sure there must be a method to do scsi to usb.

I just want to back up the stuff on this HD before I format it to remove some of the bad blocks on the drive and start afresh (on a whopping 20mb drive!)

Any ideas much appreciated :)
Is this the hardware ?

http://www.bigbookofamigahardware.com/b ... spx?id=534
adieu

Asus CS10 Chromebit / HP Envy 4500 Wireless Printer / Raspberry Pi Model 2B v1.1 / RealVNC Software...

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bugsy_malone 666
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Re: Rpi as a SCSI hard drive?

Tue Dec 02, 2014 8:27 pm

Thats the very same!

So thats what I have which works with the Amiga fine, but I need to get the files from the hard drive and wondered if it was possible to make the Rpi pretend to be scsi hard drive so that when plugged into the back the amiga would just see another Hard drive that I could copy all the files over to.

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DougieLawson
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Re: Rpi as a SCSI hard drive?

Tue Dec 02, 2014 8:41 pm

Forget it. The chances of being able to wire a SCSI connector to the GPIO pins and get the RPi to emulate the signals and data are close to zero.
Note: Having anything remotely humorous in your signature is completely banned on this forum. Wear a tinfoil hat and you'll get a ban.

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hippy
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Re: Rpi as a SCSI hard drive?

Tue Dec 02, 2014 8:57 pm

There are USB-SCSI interfaces which might be the quickest and easiest route to take.

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bugsy_malone 666
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Re: Rpi as a SCSI hard drive?

Wed Dec 03, 2014 1:43 pm

DougieLawson wrote:Forget it. The chances of being able to wire a SCSI connector to the GPIO pins and get the RPi to emulate the signals and data are close to zero.
I was just putting forward the suggestion.

as the other guy mentions you can get usb to scsi, I figured if you can get a little device like that would it not be possible to hook it up in other ways.

the only thing with the usb to scsi is I am pretty sure they are design to plug scsi devices into rather than for plugging a device into scsi?

gregeric
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Re: Rpi as a SCSI hard drive?

Wed Dec 03, 2014 2:56 pm

For just a one-off ~20MB of data, what about serial port?

dave j
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Re: Rpi as a SCSI hard drive?

Wed Dec 03, 2014 4:01 pm

Linux supports the Amiga filesystem. Could you possibly plug the drive into a PC and copy the data from there?

I looked into adding a SCSI interface via GPIO. Whilst the B+ has enough pins for an 8 bit interface and the Linux SCSI subsystem's layering would make writing the software relatively easy, bit banging GPIO pins to support the even the slowest data rate (5Mb/s) would be beyond the Pi. There's a slight possibility that something could be done with the secondary memory bus and DMA but, without details of the secondary memory bus, that's currently a non starter.

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cyrano
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Re: Rpi as a SCSI hard drive?

Wed Dec 03, 2014 4:15 pm

bugsy_malone 666 wrote:as the other guy mentions you can get usb to scsi, I figured if you can get a little device like that would it not be possible to hook it up in other ways.

the only thing with the usb to scsi is I am pretty sure they are design to plug scsi devices into rather than for plugging a device into scsi?
I have seen three of these USB to SCSI adapters. They're alle the same hardware, work only for SCSI disks, not scanners and such. And not for a SCSI system connection.

There are three different drivers and none of those works with Linux, as far as I can remember. Performance is abysmal. And the drivers certainly need to be recompiled for the RPI. And there's only one to be had today, a Microtech for 179 $ on Amazon...

Looks like the serial connection is your best bet, certainly if you only need to transfer once.

OTOH PCI SCSI cards for an old PC are a dime a dozen...

itsmedoofer
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Re: Rpi as a SCSI hard drive?

Wed Dec 03, 2014 4:30 pm

Hi,
bugsy_malone 666 wrote:
I just want to back up the stuff on this HD before I format it to remove some of the bad blocks on the drive and start afresh (on a whopping 20mb drive!)

Any ideas much appreciated :)
I have a working A1200 with Blizzard 1260+SCSI module, I could offer my services and hook your drive up to that..... At the moment I have an external enclosure with a CD ROM fitted, could easily pop your drive in though....

Other than that......

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Re: Rpi as a SCSI hard drive?

Wed Dec 03, 2014 4:51 pm

The RPi has been made to be a pretend floppy drive for a real amiga:

http://amigadrive.blogspot.co.uk/2013/1 ... loppy.html

includes write support as well - read/writes to ADF files on SD card.

[edit] appears to give two virtual floppy drives to the Amiga.

A600/1200/4000 are much easier as you can get cheap IDE to CF adaptors
Android app - Raspi Card Imager - download and image SD cards - No PC required !

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bugsy_malone 666
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Re: Rpi as a SCSI hard drive?

Fri Dec 05, 2014 1:30 pm

I have already built the RPi drive and its great, but the limitation with it is the diskette size. It acts like an original drive and I even made a load of virtual blank disks for the pi, but alas the few files I need of this scsi HD are a bit big for disks.

I might have an actual scsi drive somewhere hiding in a cupboard, but I though I have pis available so might have been able to do something with them. Maybe I'll just wait till I dig out one of my beasts!

itsmedoofer
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Re: Rpi as a SCSI hard drive?

Fri Dec 05, 2014 1:50 pm

Hi,

If you use Abackup on the miggy it will span big files across multiple disks.

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bugsy_malone 666
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Re: Rpi as a SCSI hard drive?

Fri Dec 05, 2014 2:54 pm

Hmm I did not know about that! Maybe I'll have to read into it. :)


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rpdom
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Re: Rpi as a SCSI hard drive?

Fri Dec 05, 2014 7:02 pm

I reckon the Pi could just about emulate SCSI via GPIO, but it would be tricky to do. After all, the BBC Micro emulated a form of SCSI (I believe it was actually SASI) via its 1MHz bus connector with the help of a few simple buffer chips.

So if a 6502 at 2MHz with 32KB or RAM can do it, surely an ARM at 700MHz with 256MB or more of RAM can :-)

mung
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Re: Rpi as a SCSI hard drive?

Sat Dec 06, 2014 1:51 pm

I am sure its possible, but it would need someone with a lot of enthusiasm and time to implement it.

I think also require level conversion as most scsi is 5volt signals though some I think maybe 3.3volt?

I actually was considering a similar project to create a virtual smart media card from a pi SM card are very expensive thesedays and rather rare but there is quite a lot of good equipment that requires SM (particularly digital music and sysnthesiser equipment)

I looked at the possibility and I guestimated that a rpi virtual SM card would be about 1000hours project (I could not justfy 1000hours as I have other hobbys more important to me).

The general work required would be:

1)Research the hardware interface standard (electrical signals and buffer circuits required)
2) Research the data Xfer protocol what commands are sent and recieved and what they do with data.
3) look at the linux kernel drivers available are they hackable do they give clues to data protocols and hardware.
4) write the required gpio driver and filesystem interface for linux and rpi.
5) test and debug

A really enthusiastic hobby developer could probably get something that sort of works in 6 months to a year of weekend hacking and $10 of electronic components.

Would also be a good degree level project for a final year university student if any EE professors want to assign it to a student, and very useful for many people with old hardware they still want to use.

A quick google search shows some scsi information and standards

http://en.wikipedia.org/wiki/Parallel_SCSI
http://www.paralan.com/scsifaq/scsifaqanswers.html
http://www.pcguide.com/ref/hdd/if/scsi/protDiff-c.html

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Re: Rpi as a SCSI hard drive?

Sat Dec 06, 2014 8:16 pm

Android app - Raspi Card Imager - download and image SD cards - No PC required !

mung
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Re: Rpi as a SCSI hard drive?

Mon Dec 08, 2014 12:00 am

mikerr wrote:Serial port for file transfer:
http://www.amigaforever.com/ae/
and internet
http://www.amiga.org/forums/showthread.php?t=67191
Wtf is wrong with you?

You should be answering the question asked and encouraging people to create something new and useful, not trying to divert them to something that has been done already and will not further the rpi ecosystem.

Using the rpi as a virtual scsi disk is a doable hobby project there are more than 16 free gpio data lines and all the necessary information to implement it is available from google search.

Someone should do this project, if there is no one that wants to then I will put it on my todo list, but I doubt I will get it done before 2020 as there are lots more things I have higher priority of.

The thread subject is SCSI not serial transfers!

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Re: Rpi as a SCSI hard drive?

Mon Dec 08, 2014 12:37 am

mung wrote:Wtf is wrong with you?
no mung!

what is wrong with YOU!

That not how you treat others that just want to help with a practical solution for a problem.

Behave! go read the forum rules!

the problem wasn't that for some esoteric reason a SCSI interface must be designed, it is that the OP thought that this was the only solution for his problem, thus pointing out that other solutions to the problem may exist is perfectly fine!

also just that "there are enough GPIO's" doesn't mean a thing!

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Re: Rpi as a SCSI hard drive?

Mon Dec 08, 2014 1:32 am

mahjongg wrote: the problem wasn't that for some esoteric reason a SCSI interface must be designed,
Actually, it *is* - and remains so unless and until you apply the supercilious advice contained in my signature.

Go back and re-read the OP's OP. It couldn't be clearer as to what he wants to do and what he wants help with.

I fully agree with "mung", in that anyone can do a simple serial file transfer; it would be cool to do what the OP wants to do (even if it isn't strictly necessary).
And some folks need to stop being fanboys and see the forest behind the trees.

(One of the best lines I've seen on this board lately)

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bugsy_malone 666
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Re: Rpi as a SCSI hard drive?

Mon Dec 08, 2014 11:30 am

I had forgotten what I asked originally, as my primary goal is to get the files off my hard drive so I can reformat it.

However going forward, there is a fair amount of potential in the idea of a Rpi as an actual replacement drive, look at the Rpi Diskette replacement, I built one of those and its ace!

As I have researched more and more, I have found there is alot of other equipment that utilises scsi, including apples, sound recording equipment and so on, like the Rpi diskette drive, it would prove very useful to have a scsi drive replacement as it goes outside of just an amiga.

an even more useful concept would be if you could get the pi to behave in 2 ways, the first being as a scsi drive itself, allowing for the use of the SD card as the scsi hard drive a device, but then a way of mapping the usb port as another device if something was plugged in, so for instance multicard readers, CDrom drives, usb sticks and portable hard drives.

Something like this would definitely go big in the Amiga world, I think other areas too, opening up the possibility of modern data storage with just one plug in device!

Suddenly I want to build it! I just dont know enough to do it yet :(

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mahjongg
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Re: Rpi as a SCSI hard drive?

Mon Dec 08, 2014 8:53 pm

Joe Schmoe wrote: Go back and re-read the OP's OP. It couldn't be clearer as to what he wants to do and what he wants help with.
Nothing you are saying condones the tone of speech used by mung.
Also, it seems that simply transferring the files of the disk serially is at least part of a possible solution, reading the OP's latest post.
Designing a SCSI interface might be a neat idea, but for the OP it is definitely NOT the sole solution, seems more like someone has a hobbyhorse idea he wants to encourage.

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bugsy_malone 666
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Re: Rpi as a SCSI hard drive?

Tue Dec 09, 2014 7:36 am

Alas, an idea it is. I am fine for building stuff, just not from scratch. I can work some stuff out and I can adapt ideas, but something like this is currently a little beyond me, maybe I'll get there.

I think its got alot of potential though.

Artlace
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Re: Rpi as a SCSI hard drive?

Fri May 05, 2017 6:54 pm

Hi all,

I know it's an old thread but this guy did something similar:

http://hackaday.com/2017/05/01/the-rasp ... si-device/

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