minnie.tuhs.org/unixen.tar/unixen/PDP-11/Distributions/other/Venix/RX50.notes

Internet Message Format | 1996-02-17 | 31KB

From [e-mail] Tue Aug  4 08:14:38 1992
From: [e-mail] (Barry Kort)
Newsgroups: comp.sys.dec.micro
Subject: Re: reading rainbow disks on a '386 PC
Date: 2 Aug 92 11:53:41 GMT
Organization: MicroMuse
In-reply-to: [e-mail]'s message of 1 Aug 92 01:10:53 GMT

I use the RX50DRVR on my AT which allows my 1.2 MB drive to read RX50
diskettes.  What this does is to create a new driveletter (F:) which
spins the HD drive as if it were an RX50 drive.

RX50DRVR does not know anything about the directory structure on
the disks.  If I do 'dir F:' it assumes DOS directory structure,
which works fine on Rainbow diskettes, since they use the DOS
directory structure.

To read RT11 formatted diskettes, there is a utility called RT11
which groks the RT11 file structure.  I have not yet found a similar
utility which handles the RMS-11 file structure of the PRO 3xx series.

I can use Norton Utilities with RX50DRVR to examine the RX50 diskette
in the F: drive, but then I am accessing the diskette sector by sector,
not by logical file.

I haven't explored the new utilities from the gentlemen in the Former
Soviet Union who have announced some DOS environment tools for
manipulating RX50 diskettes.

Using RX50DRVR in combination with the RT11 utility program, I can
low-level format a blank HD diskette as an RX50 diskette, then
put it in the PRO and do a high-level RMS-11 style Initialization.
This allows me to create new RX50 diskettes out of plain old unformatted
or recycled 1.2 MB HD diskettes.

Using Venix on the PRO, I can do a raw image copy of a diskette in one
drive to a blank diskette in another drive.  (This kind of copy will fail
if the target diskette has any bad sectors, since there is no attempt
to rearrange sectors to detour around any bad blocks.)

Finally, by hooking up the PRO to a Unix or DOS machine via the
COM port (or to a Unix host via Ethernet/DECnet if you have a DECNA
card), you can transfer files via any number of techniques, ranging
>from straight ASCII upload/capture using ordinary terminal emulators,
Kermit file transfers if you have Kermit on both machines, or by
DECnet file transfer using NFT or dcp utilities.

None of this is particularly trivial to implement, but the bottom
line is that there are many ways to pull files off RX50 diskettes
and transfer them to Unix or DOS machines.

Barry Kort

From [e-mail] Tue Aug  4 08:14:48 1992
From: [e-mail] (Andy Hakim)
Newsgroups: comp.sys.dec.micro
Subject: Re: reading rainbow disks on a '386 PC
Date: 2 Aug 92 19:45:22 GMT
Organization: University of Houston
X-Newsreader: Tin 1.1 PL4

[e-mail] (Barry Kort) writes:
:
: Using RX50DRVR in combination with the RT11 utility program, I can
: low-level format a blank HD diskette as an RX50 diskette, then
: put it in the PRO and do a high-level RMS-11 style Initialization.
: This allows me to create new RX50 diskettes out of plain old unformatted
: or recycled 1.2 MB HD diskettes.
:
: Using Venix on the PRO, I can do a raw image copy of a diskette in one
: drive to a blank diskette in another drive.  (This kind of copy will fail
: if the target diskette has any bad sectors, since there is no attempt
: to rearrange sectors to detour around any bad blocks.)


Another method of obtaining a formatted disk for the Pro-3xx, is to
use an image copy program called Teledisk (shareware) for the PC.  Not only
does this program allow you to do a disk-to-disk copy, but it can also
store a disk into a file (on the PC).  This way, it is possible to keep an
image file of a blank P/OS formatted disk, and then crank out new copies
easily.

In my experience, low density disks (360k) on a high density (1.2m) AT class
drives seem to work out best.

-andy

From [e-mail] Tue Aug  4 08:14:56 1992
From: [e-mail] (Charles Lasner)
Newsgroups: comp.sys.dec.micro
Subject: Re: reading rainbow disks on a '386 PC
Date: 3 Aug 92 06:39:56 GMT
Reply-To: [e-mail] (Charles Lasner)
Organization: Columbia University
Nntp-Posting-Host: watsun.cc.columbia.edu

In article <[e-mail]> [e-mail] (Andy Hakim) writes:
>
>Another method of obtaining a formatted disk for the Pro-3xx, is to
>use an image copy program called Teledisk (shareware) for the PC.  Not only
>does this program allow you to do a disk-to-disk copy, but it can also
>store a disk into a file (on the PC).  This way, it is possible to keep an
>image file of a blank P/OS formatted disk, and then crank out new copies
>easily.

Where can I obtain Teledisk?  Does it require any low-level preformatting
of the media on the target?

IF you use DR-DOS and RAINDOS (but not RX50DRVR) you can use DISKCOPY and
DISKCOMP to copy RX50 MS-DOS diskettes to each other, or to files on the
hard disk:

DISKCOPY E: C:\RX50DISK.IMG

DISKCOPY E: E:

DISKCOPY C:\RX50DISK.IMG E:

DISKCOMP E: C:\RX50DISK.IMG

When writing the file or disk image onto a target disk, the diskette has to
be already formatted as a low-level RX50, yet there are no high-level
considerations, so non-DOS RX50's can be directly used as targets!

Of course input diskettes have to already be MS-DOS RX50 DECmate II/Rainbow
diskettes because of DOS restrictions.

Note that DOS 5 cannot do anything but "standard" disk sizes, and can't
copy disk images to files at all.

>
>In my experience, low density disks (360k) on a high density (1.2m) AT class
>drives seem to work out best.

And without hub rings is better.  If you suspect that a disk is actually
high-density when it has no hub rings, there is a simple test:

Just format it as a normal 1.2 Meg disk.  a low-density diskette will get
hundreds of Kbytes in bad sectors, while a HD diskette will get little or
no errors, thus proving it unsuitable for RX50 purposes.  Most disks with
hub rings are already clearly low-density, but after you remove them, this
will prove a quick check for actual diskette formulation.

cjl

From [e-mail] Tue Aug  4 08:15:02 1992
From: [e-mail] (Andy Hakim)
Newsgroups: comp.sys.dec.micro
Subject: Re: reading rainbow disks on a '386 PC
Date: 3 Aug 92 16:42:35 GMT
Organization: University of Houston
X-Newsreader: Tin 1.1 PL4

[e-mail] (Charles Lasner) writes:
:
: Where can I obtain Teledisk?  Does it require any low-level preformatting
: of the media on the target?
:
I checked the ftp site "wuarchive.wustle.edu", it is in directory
"mirrors2/msdos/dskutl" as file "teled212.zip".

Nope, this one does not require any low level preformatting.  It's possible
to stick in a brand new ds/dd and let it go.  Incidently, teledisk is
made by the same people, Sydex, who make 22disk.

-andy

From [e-mail] Tue Aug  4 08:15:11 1992
From: [e-mail] (Andy Hakim)
Newsgroups: comp.sys.dec.micro
Subject: Re: reading rainbow disks on a '386 PC
Date: 3 Aug 92 16:54:30 GMT
Organization: University of Houston
X-Newsreader: Tin 1.1 PL4

: I checked the ftp site "wuarchive.wustle.edu", it is in directory
: "mirrors2/msdos/dskutl" as file "teled212.zip".

Correction, it's spelled "wuarchive.wustl.edu" with a missing 'e'.

Host nic.switch.ch   (130.59.1.40)
    Location: /mirror/msdos/dskutl
      FILE      rw-rw-r--     93805  Dec 23  1990   teled212.zip

Host ftp.uu.net   (137.39.1.9)
    Location: /systems/msdos/simtel20/dskutl
      FILE      rw-r--r--     93805  Dec 22  1990   teled212.zip

Host wuarchive.wustl.edu   (128.252.135.4)
    Location: /mirrors3/garbo.uwasa.fi/diskutil
      FILE      rw-rw-r--     94075  Dec 11  1990   teled212.zip
    Location: /mirrors/msdos/dskutl
      FILE      rw-r--r--     93805  Dec 23  1990   teled212.zip

archie>

From [e-mail] Tue Aug  4 08:15:17 1992
From: [e-mail] (Charles Lasner)
Newsgroups: comp.sys.dec.micro
Subject: Re: reading rainbow disks on a '386 PC
Date: 4 Aug 92 05:55:11 GMT
Reply-To: [e-mail] (Charles Lasner)
Organization: Columbia University
Nntp-Posting-Host: watsun.cc.columbia.edu

In article <[e-mail]> [e-mail] (Andy Hakim) writes:
>[e-mail] (Charles Lasner) writes:
>:
>: Where can I obtain Teledisk?  Does it require any low-level preformatting
>: of the media on the target?
>:
>I checked the ftp site "wuarchive.wustle.edu", it is in directory
>"mirrors2/msdos/dskutl" as file "teled212.zip".
>
>Nope, this one does not require any low level preformatting.  It's possible
>to stick in a brand new ds/dd and let it go.  Incidently, teledisk is
>made by the same people, Sydex, who make 22disk.
>
>-andy

Sydex also makes RAINDOS.

I suspect that teledisk will only make sector-compatible descendents though,
so if I have a specially layed-out version of a diskette (such as 2:1
interleave or staggered, etc.) the descendent will lose that aspect of
optimization, and will instead become "vanilla" RX50 format in the
case of RX50 diskette.

The point is that certain software, especially for DECmates not specifically
geared to CP/M-80, and *any* bootable DECmate diskette (including CP/M-80) the
format used in stock RX50 layout is non-optimal.  There are different
requirements for different specific applications, but just as on PC's, the
use of non-interleaved non-staggered disks can be demonstrated to be
inferior to a variant in terms of sector ordering at the low format level.

Rainbow MS-DOS disks have an implied software interleave of 2:1 for the
FAT area, and 1:1 in the rest; this is in software, so the standard disk
layout should be maintained, except that the *stagger* is not taken into
account.  Thus, like a PC, Rainbow MS-DOS disks should be formatted with a
stagger of 2 per track.  Thus track 1 is layed out 1,2,3,4,5,6,7,8,9,10 and
track 2 is layed out 9,10,1,2,3,4,5,6,7,8.  When the disk seeks from track 1
to track 2, it will thus miss 9 and 10, but immediately find 1.  Were the
stagger not there, it would miss 1 and 2, and reject 3,4,5,6,7,8,9 while
waiting for 1 to come around again.  Thus staggering relieves rotational
latency.

For the DECmate, there are two additional problems:

All bootable diskettes require the logically sequential reading of tracks
78, 79 in the order 1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10.  But the RX
interface of the DECmate can't perform 1:1 interleave ever, so this is
anti-optimal not only in stagger but more importantly in interleave.  Thus,
this area of the disk should be formatted with an interleave of 2:1 as well
as a stagger of 2.  Thus the disk is layed out:

track 78: 1,6,2,7,3,8,4,9,5,10
track 79: 5,10,1,6,2,7,3,8,4,9

This restriction is based on the ROM routines that read in this area in linear
order.  This is mostly why all DECmates take so long to boot up!  Changing to
a better sector order will chop seconds out of the boot time.

Further, all systems other than CP/M-80 require some form of help, mostly
applying the stagger that helps the Rainbow as well (again other than CP/M).
For DECmate MS-DOS, tracks 0-3 should be in 1-1 interleave because the software
already maps the disk in 2:1 usage.  tracks 4-79 should be formatted 2:1
interleave to help out the RX interface when the Rainbow-optimal ordering
is invoked (similar to the DECmate ROM access, and just as inefficient on
a DECmate).

OS/278 does a software 2:1 interleave, so the only help needed is a
disk-wide stagger factor of 2.

Note that RT-11 and all other -11-oriented disks should use stock format only
because this superior software maps all sectors to include both the 2-1
interleave and stagger of 2 already.

So, if Teledisk is a *really* good utility, it won't disturb the format's
stagger and interleave as it copies the disks!

cjl

From [e-mail] Tue Aug  4 08:15:23 1992
From: [e-mail] (Charles Lasner)
Newsgroups: comp.sys.dec.micro
Subject: Re: reading rainbow disks on a '386 PC
Date: 3 Aug 92 05:39:27 GMT
Reply-To: [e-mail] (Charles Lasner)
Organization: Columbia University
Nntp-Posting-Host: watsun.cc.columbia.edu

In article <[e-mail]> [e-mail] (Barry Kort) writes:
>I use the RX50DRVR on my AT which allows my 1.2 MB drive to read RX50
>diskettes.  What this does is to create a new driveletter (F:) which
>spins the HD drive as if it were an RX50 drive.

RX50DRVR, like RAINDOS, creates a new logical drive past your last existent
drive, so it's F: for you because you apparently have an A: through E: before
the driver gets loaded in CONFIG.SYS.

>
>RX50DRVR does not know anything about the directory structure on
>the disks.  If I do 'dir F:' it assumes DOS directory structure,
>which works fine on Rainbow diskettes, since they use the DOS
>directory structure.

That's not quite true, since the disk organization has to be DOS as implemented
on DECmate II MSDOS/Rainbow MS-DOS only.  It is true only in the sense that
you can make your own BIOS calls to read the disks yourself without caring
about the significence.  But that's no different from doing so with any
floppy on a PC.

>
>To read RT11 formatted diskettes, there is a utility called RT11
>which groks the RT11 file structure.  I have not yet found a similar
>utility which handles the RMS-11 file structure of the PRO 3xx series.

Where can I get this RT11 utility?  It sounds useful.  Does it specifically
require/recognize the RX50DRVR or does it merely work in an innocuous way
with the same drive letter?  (Would it work also with A:? or must it have
RX50DRVR present.  If so, would it work with RAINDOS as an alternative?)

>
>I can use Norton Utilities with RX50DRVR to examine the RX50 diskette
>in the F: drive, but then I am accessing the diskette sector by sector,
>not by logical file.
>
>I haven't explored the new utilities from the gentlemen in the Former
>Soviet Union who have announced some DOS environment tools for
>manipulating RX50 diskettes.

Re the Soviet-originating files:

The files come with a piece of shareware originating in Italy that intercepts
DOS's calls for formatting commands, so that "odd" sizes, such as using:
FORMAT A: /T:80 /N:10 are now legal.  The result is a double-sided disk that
is quite suitably low-level formatted for RX50, but the high-level is PC
compatible, *not* DECmate/Rainbow's idea of MS-DOS, and specifically must be
used on a "normal" drive and *not* with RX50DRVR.  All media indicators are
stock PC-type, not RX50.  However, since the low-level is now correct, and
errors are recorded in a way that FORMAT indicated when it finished, and can
be re-confirmed with CHKDSK, etc., the media can be determined to be error-
free hopefully.  If so, then the companion program RX50INIT that comes with
RX50DRVR can be used to initialize the directory so DECmate/Rainbow MS-DOS
likes the disk, and of course the RX50DRVR-controlled logical device such as
F: in your example.  Note also that RX50INIT can be used with RAINDOS as well.
Also, RX50INIT requires ANSI.SYS be loaded purely for cosmetic reasons.
RX50DRVR and RX50INIT were designed for DOS 3.3 usage.  They don't support the
extensions to DOS brought into versions 4 and 5, so there are some problems.
RX50INIT fails totally in those two systems, and CHKDSK can't work there
either.  With some adjustment to the BUFFERS= statement in CONFIG.SYS, they
can be made to work for read/write purposes under DOS 4 or 5.


When used with DR-DOS 6.0, all RX50DRVR and RX50INIT functions work fine.


>
>Using RX50DRVR in combination with the RT11 utility program, I can
>low-level format a blank HD diskette as an RX50 diskette, then
>put it in the PRO and do a high-level RMS-11 style Initialization.
>This allows me to create new RX50 diskettes out of plain old unformatted
>or recycled 1.2 MB HD diskettes.

Just a word about using HD media:

You can't reliably use HD media on an actual RX50, because the coercivity
is too far off in HD media.  It was designed for the higher-frequency
recording of the "real" 1.2 Meg format (500 KHz) and not the 250 KHz recording
rate of the RX50, which is actually the same as good 'ol DS/DD media (360K
kid of media).  Some revisions of RX50 drive in comination with certain RX
controllers in some DEC machins fare better than others, but it can be
demonstrated that a lot of combinations don't particularly "like" HD
media.

The designated media for RX50 is Maxell MD1DD-RX50 or equivalent, which is
what used to be called "quad" media.  This is well-honed low-density media,
so it is rated for use on 96 TPI (80 track) drives, not just 48 TPI (40 track)
drives as is usual.  Note that MD2D is not MD2DD.  (The 2 just means two-sided
which for all intents and purposes today can be ignored; virtuall *all* media
is actually made double-sided :-).)  The DD means 80-track support, but since
most media are made well-honed, most cheap disks can support 80 tracks anyway.
These disks will *not* cause I/O errors on any RX50!  However, long-term usage
requires the hub rings be removed completely (use alcohol to get the sticky
stuff off, or ask your supplier for no-hub disks!).  Failing to remove
hub rings means eventually the disks will get unreliable sooner than they
ought to due to registration problems.  All 96 TPI disks have this problem.
Note that MD2HD and MD1DD don't have hub rings!  It is rumored that there is
a "premium" line of diskettes from Fuji apart from their standard line of
inexpensive diskettes that has a specially reinforced hub area, that isn't
a hub ring per se.  If the same mechanism is used in both HD and DD media,
then the DD type would be the best thing today to use with impunity for
RX50.  Clearly the MD1DD or MD2DD or MD1DD or the 3M equivalents are too
expensive, considering that what we want are the cheapest types of diskettes
with the hub rings never added.  (We don't want to pay more for less!)

Re RT-11 utility:

I don't know anything about the RT11 utility program, but RX50DRVR cannot
format disks; the code lacks support for the FORMAT command, and also some
calls needed by both CHKDSK and FORMAT.  Attempts to use either on DOS 4
or 5 will get error messages.  Even on 3.3, where CHKDSK is more "forgiving"
you still get the message about "format not supported on device" when
using RX50DRVR.  So, if your claim for formatting is true, the RT11 utility
must contain low-level formatting code of its own, and perhaps only needs
RX50DRVR to locate the proper device?

RAINDOS is a share-ware mostly superset of RX50DRVR, and it totally supports
CHKDSK and FORMAT in DOS 4 and 5.  It works fine with RX50INIT (assuming that
RX50INIT can work!) and suffers from only two known problems:

1)    Should you specify a format command with the FORMAT F: command,
and the O/S is DR-DOS 6, then if it really does attempt a low-level format,
it gets a cryptic error message and fails.  Note that MS-DOS 5 and DR-DOS 6
will always attempt a "quick" format if possible, unless over-ridden.  This
case of a quick format doesn't fail, but also isn't formatting!  Just
rewriting a cleaned-up high-level format directory initialize.

2)    It is sometimes strangely slow, as compared to RX50DRVR where both
could work.  When using Norton 4.5's DT program, RX50DRVR handles the
disk at normal speed, and allows DT to mark bad clusters (if any) quite
nicely.  When RAINDOS is used, it causes many recalibrates for unknown
reasons.  In some cases, the sloth isn't that noticeable, but this is a
sore point usage.

Otherwise, RAINDOS is a total replacement for RX50DRVR, or so it would seem.
Norton NU treats RX50DRVR diskettes and RAINDOS diskettes equally since it
does one-sector I/O.

>
>Using Venix on the PRO, I can do a raw image copy of a diskette in one
>drive to a blank diskette in another drive.  (This kind of copy will fail
>if the target diskette has any bad sectors, since there is no attempt
>to rearrange sectors to detour around any bad blocks.)
>
>Finally, by hooking up the PRO to a Unix or DOS machine via the
>COM port (or to a Unix host via Ethernet/DECnet if you have a DECNA
>card), you can transfer files via any number of techniques, ranging
>from straight ASCII upload/capture using ordinary terminal emulators,
>Kermit file transfers if you have Kermit on both machines, or by
>DECnet file transfer using NFT or dcp utilities.
>
>None of this is particularly trivial to implement, but the bottom
>line is that there are many ways to pull files off RX50 diskettes
>and transfer them to Unix or DOS machines.
>
>Barry Kort

If the Soviet files prove to work, and apparently requiring the Italian
TSR shareware program, we can probably make Files-11 RX50 diskettes as well.
I have just received these programs and will be evaluating them when feasible.
I am still working with the accompanying Italian shareware which has some
interesting "generic" features of its own with respect to the entire RX50
issue.  I suspect that its presence enhances any of these utilities, although
it's possible redundant and perhaps extraneous to some of the utilities.

In any case, there are many ways to get files moved around.

Another excellent package is 22DISK from Sydex, the same shareware author
as RAINDOS.  This package low-level formats RX50's in either DECmate CP/M-80
or Rainbow CP/M-80/86 format.  (They are similar, but not identical, although
they can read each other's disks no sweat; it's a matter of interleave, etc.
and a throughput issue, not a format per se issue.)  It then high-level
formats the disks for CP/M usage.  So, its a good place to do the low-level
formatting required for all of these other utilities.  For example, on
DR-DOS 6, you first run 22DISK to format the disk, then use RX50INIT to get
an RX50 MS-DOS DECmate/Rainbow high-level structure, and then can use
RAINDOS to transfer files, run CHKDSK, and do quick-formats with FORMAT /Q,
etc.  Notice this avoids all of the Raindos/DR-DOS interaction :-).

22DISK can get directory listings of CP/M disks, and can transfer files
to/from MS-DOS from/to the designated CP/M diskette.  It supports literally
hundreds of CP/M formats, which implies many low and high-level support
variants.  This program is highly reminiscent of the former Rainbow, and
later PC-based "Media Master" program, but is for PC/MS-DOS only, and
requires HD drives for the RX50 formats.

I believe there is an obscure PRO option for a CP/M-80 board, so this might
be yet another way to get files in/out of a PRO.

So, like cats, there are many ways to "skin" an RX50 :-).

cjl

From [e-mail] Tue Aug  4 08:15:29 1992
From: [e-mail] (Charles Lasner)
Newsgroups: comp.sys.dec.micro
Subject: Good report on Teledisk.
Date: 4 Aug 92 07:27:25 GMT
Reply-To: [e-mail] (Charles Lasner)
Organization: Columbia University
Nntp-Posting-Host: watsun.cc.columbia.edu

I have down-loaded Sydex's teledisk, and have found it to exceed my
expectations in some useful ways.

For starters, all of my attentions are based on the problems of distributing
RX50 diskettes not necessarily in stock format, and not yet having any
satisfactory way of creating the necessary disks.

Background:

There are several desirable variant formats for RX50 that have been discussed
elsewhere.  The only known program to create them is FDFORMAT for PC's.  While
this freeware program is generally quite good, it has a few crucial bugs that
make it unsuitable for RX50 usage.  It is conceivable that this will be
solved by using some additional/non-standard parameters to FDFORMAT to create
usable disks, but in any case, the use of all obvious parameters yields disks
that are flakey on some RX50's, and downright unreadable on others.  In
addition, these disks are so messed up that a DECmate can't even WRITE on the
disks and read back what it just wrote reliably!  Yet, this isn't a media
problem because it can be demonstrated that the problem disappears by
low-level format of the same diskette with either Sydex's RAINDOS or 22DISK
packages.  (Note that *some* RX50 systems using some newer-designed controllers
and/or higher revision drives and/or RX50-compatibility modes on different
drives have little or no problems with these FDFORMATted diskettes; indeed
the diskettes are fine on a PC; there's some low-level detail that's incorrect
about FDFORMATted diskettes.  Some parameter is being set to a PC-acceptable
value that doesn't center on RX50's requirements.  Perhaps this will be
uncovered at a later time obviating this entire discussion.  Until such a
time, FDFORMAT cannot be used to create RX50 diskettes that are readable on
*all* RX50 systems.  FDFORMAT also has a few other operational bugs, such as
incorrect recognition of certain I/O errors, etc., but these are exception
cases, and for all other PC purposes, it serves quite admirably.)

The reason why FDFORMAT is desirable is that it is the only known program
capable of creating the variant RX50 formats where the format must be
done with interleave and stagger factors, especially if the disk must have
"zones" where the format changes.  For example, to create a disk best suited
for DECmate OS/278 usage, the following *TWO* commands should be given:

FDFORMAT A: /T:80 /N:10 /1 /Y:2 /I:2
FDFORMAT A: /T:78 /N:10 /1 /Y:2

The first command creates a disk with an interleave of 2:1 and a stagger of
2 throughout.  The second command changes tracks 0-77 to have 1:1 interleave
and a stagger of 2 throughout.

When OS/278 is copied onto such a diskette, the "slushware" tracks are read
in much faster than on standard RX50 diskettes, and all access to the rest of
the diskette is speeded somewhat because of the stagger factor which overcomes
the software's lack of stagger mapping.  But since the software does map the
sector order into a 2:1 interleave, the hardware order must stay in 1:1
interleave sequence.

This would be a nice disk to use for the intended purpose, but many DECmates
will be unable to read this diskette.  Literally, it will get a CRC error
on *every* sector!  Furthermore, if you attempt to write an image of the
software onto this diskette, it will get a CRC error on *every* sector even
though it just wrote the disk out!

Enter Teledisk to the rescue!

When I read Teledisk's documentation, I had doubts that it could solve
this problem, because I noticed it could be quite "smart", perhaps *too*
smart!  It claims that it can get around certain copy-protection methods
by virtue of how it operates, so I figured that it would likely copy the
problems of FDFORMAT as well :-(.  Or, alternatively, it might guess that
the diskette was an RX50 and proceed to format it in a stock manner, thus
destroying the optimization applied by using the two FDFORMAT commands instead
of just using RAINDOS or 22DISK to create stock low-level RX50 diskettes.

Well, I was wrong on both counts!

Teledisk understands how to maintain sector order, and pointed out the
change of interleave from 1:1 to 2:1 at track 78, so that problem is
hurdled.

Teledisk understands that these sectors should be formatted with apparently
the same parameters as the formatting routines in 22DISK and RAINDOS, so the
resultant disk *is* readable on DECmates!  Of course, this is *not* an
"exact" copy, but rather it is a "better" copy.  Apparently Teledisk only
writes sectors in a "sane" format, and the copy-protection they refer to
is the class of "funny" sector ordering, size, or count, not any lower-level
details.  Apparently the Sydex code at work in RAINDOS and 22DISK is also
within Teledisk, thus since Teledisk recognizes the disk as a 10-sector/track
512 bytes/sector disk, it writes it as would RAINDOS, etc., except Teledisk
is sensitive to sector ordering unlike the other Sydex programs, etc.

Thus, the descendent disk is actually *better* than the original.  I can now
therefore distribute diskettes in the intended format for working-copy usage
of the best effort of each diskette :-).

Additionally, if I modify distribution diskettes to be in their intended
format instead of their original stock format (virtually all diskettes that
need to be distributed are in stock RX50 format, because the need to create
optimal diskette layout is generally newer than the software; indeed, this
entire effort is to distribute software that performs *better* than the
original!), then the master disks should be copied with Teledisk to create
perfect copies in one step.

There are additional advantages:

Teledisk can also create an MS-DOS file that is the image of the diskette
in either a rudimentary-compressed or advanced-compressed form.  These files
can be transmitted down the net and then reconstructed on PC-AT's for use
on RX50 targets.  Since they are compressed, this minimizes the overhead
as well, etc.

So, Teledisk has made my day :-).

cjl

From [e-mail] Wed Aug  5 10:12:06 1992
From: [e-mail] (Barry Kort)
Newsgroups: comp.sys.dec.micro
Subject: Re: reading rainbow disks on a '386 PC
Date: 4 Aug 92 12:13:30 GMT
Organization: MicroMuse
In-reply-to: [e-mail]'s message of 3 Aug 92 05:39:27 GMT

Charles,

You can retreive rt11.zip by anonymous ftp from
newton.canterbury.ac.nz, 132.181.40.1, in the pub/local directory.

Barry

From [e-mail] Wed Aug  5 10:12:14 1992
From: [e-mail] (Charles Lasner)
Newsgroups: comp.sys.dec.micro
Subject: Re: reading rainbow disks on a '386 PC
Date: 4 Aug 92 18:41:23 GMT
Reply-To: [e-mail] (Charles Lasner)
Organization: Columbia University
Nntp-Posting-Host: watsun.cc.columbia.edu

In article <[e-mail]>
[e-mail] (Barry Kort) writes:

>Charles,

>You can retreive rt11.zip by anonymous ftp from
>newton.canterbury.ac.nz, 132.181.40.1, in the pub/local directory.

>Barry

Got it.  It looks nice.  It produces what appears to be a nice RT-11-like
environment on a PC for file transfers, etc., but is inferior to Teledisk
for the purpose of making a compacted image of an entire disk as a DOS
file.  Since this is a frill, it can be completely overlooked :-).

And yes, it does Format DD-type media to stock RX50 as advertised.  I will
only take you to task on the minor point: it doesn't require RX50DRVR at all.
There was a little confusion as to whether they were tied together, which is
not the case.

This program is written in Turbo Pascal.  It would seem that someone who
can understand enough TP and the quirky code to call BIOS routines should
incorporate some of RT11.PAS into FDFORMAT (also a TP-based item) since
the format routine works fine while FDFORMAT does not for RX50 as discussed
elsewhere.

Overall a nice program.

cjl