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From: GTHEALL@PENNDRLS.UPENN.EDU (George A. Theall)
Newsgroups: comp.sys.dec.micro
Subject: RE: DEC Rainbow 100 disk formats
Message-ID: <8910081903.AA26925@remote.dccs.upenn.edu>
Date: 8 Oct 89 19:38:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 48

>It seems that a DEC Rainbow formats
>disks at 400K (how odd) and cannot read normal 360K type DOS disks.

  Yes, the Rainbow and PC disk formats are different. I'm not up on
the gory details, but suffice it to say this is both a benefit and
a problem.

>Trying to read a 360K formatted disk gives the error message "non-DOS disk in
>drive A:" and if I read a 400K formatted disk in my 386 high-density drive
>it claims that the disk type is a single-sided double density 8 spt disk with
>14K used somewhere in the middle (Norton utilities).

  I suppose your first error arose because (1) the 360K disk was double
sided or (2) it was single-sided but you didn't type "MEDIACHK ON" first.
Don't forget, the RX50 drives are single-sided. Some Rainbows are
capable of reading single-sided, double-density PC floppies, but this
definitely requires running MEDIACHK first.

  Solutions: several exist. (1) You can buy an add-on drive from Suitable
Solutions which will give you complete DATA compatibility with a standard
PC XT computer. SS sells I-Drives that work with either double-density
or high density 5.25" PC floppies; there MAY be a device now which works
with the smaller 3.5" disks. (2) You can read/write to SINGLE-sided PC
5.25" PC floppies on your Rainbow as long as your drive is well aligned
and you use MEDIACHK first. (3) You can install a device driver called
RX50.SYS (or RX50DRVR.SYS) in your 386 machine. This little gem lets
you use read from and write to RX50 floppies with your high-density
drive.

>What am I doing wrong? Is a DEC Rainbow really that incompatible and more
>important, how do I transfer my software onto the DEC?

  Now this still leaves unanswered another question - will your
software actually run on your (or your friend's) Rainbow. The
Rainbow does indeed run MS-DOS (even v3.10!) but it does not have a
PC-type BIOS, keyboard, video, or even port setup. If you discover
your programs do not work "as-is", you might consider spending some
money and buy MS-DOS v3.10b and Code Blue from Suitable Solutions as
together they seem to provide fairly good PC compatibility for the
Rainbow. Cost should be around $250 (I'd tell you for certain if
I had their price list in front of me).

George

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BITNET: GTHEALL@PennDRLS               Dept. of Economics
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