Conference hydra::amiga_v1

    	Steve,
    	     Look  through some of the othe notes ie dir/tit=hard
    
    	But for the best way on an A500 you need to use the EXPANSION
    Port on the Left-Hand side with an adapter.
    
    	The D.E.C. drive are based on the ST506 (non-intelligent
    controller).An Omti 3520/Adaptec 4000 will convert the drive to
    SCSI .
    
    There are several manufactures who sell HOST/Adaptors to SCSI...
    
    		I hope this helps
    
    		Regards
    		Steve G.

    The 486 Standardization committee is specing a new file format
    for new 20-Mbyte, floppy disk drives.  I know that Supra has
    had ads with such beasties.  Since the A590 has an internal 20MB
    hard drive, I could see some applications where floppy mass storagw
    would make sense for backup. [Animation clips]
    
    If you want hybrids, I thought SCSI did that (drives, networks....)
    I'd stay very conservative on this.
    

To answer your question directly, No, there is no direct way of attaching
a hard disk to the floppy port.

RDxx drives, as mentioned, are ST-506. Also mentioned is that this is an
"unintelligent" interface. What does that mean?

ST506 devices have only the barest required hardware/firmware to do only the
most fundemental operations on the drive. For example, all an ST506 drive can
 do on it's own is read and write raw MFM data to the media, move the heads
in or out a specified number of tracks, switch heads, and tell the interface 
when a seek is complete or when one of some defined set of errors occurs
(ex. Write Fault).

The host must do everything else. For example, encoding/decoding the MFM data
from/to "bytes", finding and separating data from headers, remembering what
head/cylinder the device is on etc.

So a host for an ST506 device must have both digital and analog hardware.
(and this is why the floppy port won't work) it must have a phase lock loop
to detect data (in effect). And then encoding/decoding circuits ECC/CRC
generation, etc..


John

    
    
    Thanx for the info...
    
    I've read just about every note that mentions a hard disk and by
    now am starting to get to grips with what's needed to add a hard
    disk to the expansion port . The problem is things like the 
    Adaptec 4000 controller are impossible to get here in Ireland .
    ( I might as well be looking for space shuttle parts ).
    
    It looks like my best shot might be with the interface that Ingo
    Sturm posted from a German magazine .But there doesn't seem to be
    any news of software availability yet .. The Ompti interface should
    be more readily available as it's used in PC's .
    
    I'd love to put something like an RQDX3 and RD53 on the A500 but
    I don't know enough to write a hard disk driver and with only one
    floppy disk and no decent manuals is's very hard to get into any
    kind of programming.
    
    Would it be feasable to use say a PD 68000 assembler/disassembler
    and write a driver for an RQDX3 RD53 configuration. ?
    
    Steve...

    The RQDX3 won't work on the Amiga.  The RQDX3 interfaces between ST506
    and the Q-bus, and the Amiga doesn't have a Q-bus.  You need a
    controller that interfaces to the Amiga's bus.
        John Sauter

    
    re.5
    
    Yes John , but I'm sure you could interface the Amiga 68000 bus
    to the RQDX3 "after" the Qbus drivers on the RQDX3 . I can't see
    how this would be a problem ... But as I say the hard disk driver
    would have to talk to the RQDX3 registers.
    
    While were on the subject does anyone know how similar the programming
    interface on an RQDX3 would be to other ST506 interfaces. Are the
    RQDX3 registers similar in format to an Adaptec 4000 etc..
    What I mean is would it be totally out of the question to modify
    a hard disk driver file meant for a different interface ...
    
    Steve..
    
    

>    While were on the subject does anyone know how similar the programming
>    interface on an RQDX3 would be to other ST506 interfaces. Are the
>    RQDX3 registers similar in format to an Adaptec 4000 etc..


Ha!  (Sorry, had to laugh).  RQDX3 speaks MSCP. NOT A simple programming task
to emulate. You'ld have to even emulate the U/Q port.

John

    It's not just a matter of the drivers, there's also the buss-level
    handshake protocol.  I don't know what the Amiga uses, but Murphy's Law
    says that it won't be the same as the Q-bus.
    
    On top of that, there's MSCP, as mentioned in 2465.7.
    
    I think interfacing an RQDX3 would be more trouble than it's worth.
    You'd probably end up building a box as big as the RQDX3 itself, just
    to make it talk to the Amiga.
    
    I understand there is a device that attaches to the A500 and provides
    you with an A2000 "slot".  If this is true, you could place an A2090
    in that "slot".  The A2090 speaks ST506 (as well as SCSI) so it should
    be possible to interface an RD54 to it.  There is already driver
    software for AmigaDOS that knows how to deal with the A2090.
        John Sauter

    HARD/Floppy Hybrid == NO
    Tape/Floppy Hybrid == YES
    
    PC Magazine covers such beasties on page 27, April 25 1989.  I wonder
    if random access tape is a viable compromise.  Just wondering out-loud.
    
    Paul