Subject: DM2 formatter for RD53?

From: [email-masked] (Roger Ivie)
Date: 29 Jan 95 21:16:18 MDT

Greetings!

I suddenly and unexpectedly find myself with a surplus of large MFM hard disks,
including a couple of RD53 70 MB drives. This, of course, has me dreaming of
stashing them in my DECmate IIs. Does anyone have a formatter for the DM2
capable of doing RD53s that they are willing to send my way, or do I have to
write one?

Also, once I have them formatted, what do I do with all the space? I know I
can suck up 32MB for CP/M (four 8MB partitions). Can OS/278 handle more than
two partitions connected at once?
-- 
----------------+------------------------------------------------------
Roger Ivie      | Don't think of it as a 'new' computer, think of it as
[email-masked] |     'obsolete-ready'

---

From: [email-masked] (Charles Lasner)
Date: 31 Jan 1995 14:16:22 GMT

In article <[email-masked]>,
>capable of doing RD53s that they are willing to send my way, or do I have to

I have the so-called "clandestine" formatter in binary executable form. 
It's apparently standalone, thus can be wrapped around any form of
OS/(27)8 system or could even be transferred to COS or P?S/8 accordingly,
etc.  It's "distributed" on an OS/278 RX50 without documentation, but all
you need to give it (manually on the keyboard) are the # of cylinders and
heads.  It does (most of) the rest. 

There are several problems:

1)	It doesn't apply the slushware, but that's easily done from the 
System Test Diskette.  (Note: the STD has two functions: one formats the 
disk and applies slushware automatically, the other *just* applies the 
slushware.  The catch with the STD is that it will *ONLY* format 5,10,20 
MB disks to one head shy of their respective sizes, and will do no other 
sizes at all.  These sizes are in turn "sacred" (see below).)

2)	It cannot make any "sacred" disk sizes which leads to a problem 
with Master Menu.  Master Menu pragmatically checks for the three sacred 
sizes of one head shy of 5 or 10 or 20 MB, the three normally used disk 
sizes on DM II/III+.  Anything else is claimed to be "corrupted" when you 
attempt to use the "X" option to compress the disk.  Thus, the use of 
these disks demands manual volume placement, which means a whole lot of 
backup/restore, etc. :-(.  (My present situation: I use an ST-4096 
wasting a head to get exactly 64 MB of formatted space.  And a whole lot 
of RX50's of volume backups, although backing up per se isn't that bad an 
idea :-).)  (Note: obtaining the sources to Master Menu will likely allow 
fixing this.  Older prerelease versions of MM actually didn't mind 
alternate sizes, but cannot be used due to other internal problems.  All 
are warned not to attempt to use old MM copies to get around this - it 
will permanently corrupt your entire disk!!!)

Other than that, arbitrary disk sizes can be used.  The maximum number of 
heads is 8, even though newer disks allow up to 16.  It is rumored that 
the controller can handle more than the Rainbow limit of 1024 cylinders; 
it would be nice if an RD54 was attempted to see if you can get to 1224 
cylinders (even if wasting all of those other heads!).  If that's true, 
anyone have any leads where to find larger disks by cylinders, but with 
less heads (Microscience?).

3)	There is no facility to lockout bad blocks.  Even Master Menu's 
facility is a non-workable kludge.  What's needed is a routine to read 
test the disk and find and mark bad blocks/replacements.  (Better yet, a 
read/write test used just after the clandestine formatter even before 
systems are applied, but after the slushware is in place so there even is 
a bad block table to mark!)

I so far have been lucky in that I've found disks with no apparent 
problems.  Perhaps it's because DEC writes lower-density disks than the 
rest of the industry?  (Remember, DEC formats for 16 512 byte 
sectors/track, not 17 as in PC's, etc.)

>two partitions connected at once?

There are several problems for each system:

1)	MS-DOS for some reason cannot boot a volume larger than about 10.5 MB. 
However, non-system volumes of up to 32 MB each work fine for drive F:,
G:, H:.

2)	I cannot confirm how large CP/M-80 volumes can be, but again I 
would check if the non-system size is different max than the bootable 
system size, or if there's a problem referencing different sizes from a 
bootable floppy system.

However, there is a specific problem with CP/M-80: You cannot directly
create a volume that starts past the first 10-20 MB of disk address.  The
install diskette gets confused by the extra set high-order bits.  Thus,
the workaround is to place a CP/M-80 system on a near-empty disk or
smaller hard disk system and then use backup/restore to place the
now-existent system where you want it.  (Note: see how this couples well
with the MM limitations :-( :-).)

While both CP/M-80 and MS-DOS allow the same configuration of A:, B: RX50 
and E:,F:,G:,H: hard disk volumes (booted to E: on the hard disk 
version), a bug in the CP/M configuration prevents C: and D: from being 
accessed even if you have the second RX50.  (MS-DOS does it correctly.)  
Only up-to-8 all-floppy CP/M systems can access the second drive pair.

A side note for CP/M-80 users:  The install diskette is for any APU or 
XPU configuration, yet the systems it creates are for APU or XPU only, 
and can never be "crossed".  This even applies to bootable volumes!  
Additionally, the installation of DM II-oriented CP/M-80 must be 
performed on the DM III+ by first modifying the machine to have two 
diskette drives.  Afterwards, all will work except the HD utility's 
backup/restore feature since that only addresses the B: drive.  (Unless 
you make the second drive permanent!)

3)	COS volumes can be created by Master Menu, but are created 
corrupted.  Apparently there are COS commands to correct this after the 
fact.  However, COS is distributed with a second diskette that contains a 
"stub" version of Master Menu that redundantly includes a facility to 
delete and add volumes in COS format.  Volumes created this way are 
acceptable to COS directly.  I haven't tried any of this on a 
non-standard disk size though (used a 10 MB machine standardly formatted 
at the time).  The diskette itself is actually a bootable pre-release 
OS/278 diskette that auto-executes the COS-oriented stub derivative from 
MM.  I would not trust either the overall worthiness of the underlying 
OS/278 system compared to the released system, nor would I attempt to 
move the executable to OS/278 V2.  (This inadvertant "lock-in" is 
characteristic of a lot of early install software; apparently these 
programs were written for the "OS/278 system of the week" back then, 
etc.  Once OS/278 stabilized as more like OS/8 (as it should be!) these 
programs with their dependent kludges became as orphaned as the systems 
they were released with, etc.)

4)	OS/278 as distributed only specifically addresses RD50: and 
RD51:.  While CP/M and MS-DOS are limited to 4 logical volumes, WPS and 
OS/278 are able to access all 8 logical volumes, at least in theory.  
OS/278 needs to be reconfigured with more handlers using the SET HANDLER 
utility.  (Note: BUILD is not compatible with OS/278 specifically, but 
this can eventually be overcome!)

Distributed with OS/278 is the handler for RD52: and RD53:.  This can be 
applied directly as a replacement for the RX02 handlers (RX20: and RX21: 
for example, since hard disks and RX01/02 never meet :-).)

The designated way to create additional OS/278 volumes is through Master 
Menu directly.  The "A" command will allocate any of the other systems as 
advertised on the screen.  However, you can also indicate "OS278" as an 
undocumented choice!

There are a few problems acquiring access to the other four volumes: The 
OS/278 MOUNT program as distributed is limited to accessing logical 
drives 1-3 only (0-3 from diskette-based systems; the improvement makes 
sense; you don't want to dismount the system boot drive from a hard disk 
system!).  However, Master Menu allows you to pre-mount all 8 volumes 
(btw, this is required for WPS normally), thus this would at least allow a 
half-fixed and half remountable system, etc.

However, as distributed, there are no handlers for RD54: through RD57:.  
>From the sources, it should be fairly easy to modify for the extended 
logical volumes.

I haven't ever bothered merely because I just use a lot of MOUNT commands 
on the four available logical volumes.  This allows me to designate RD53: 
as the WPSVOL1 normally associated with WPS documents, and still have a 
system volume and two additional data volumes.  WPFLOP can convert 
document files in either direction to/from OS/278, thus allowing text 
files to go between OS/278 and WPS format.  Since both CP/M-80 and MS-DOS 
allow local conversions to/from those systems and WPS, this allows WPS 
format used as an intermediary to be the means of file conversion between 
all of these systems, etc. without resorting to floppies.

There are higher priority issues to be dealt with in improving OS/278, so 
we'll all have to "suffer along" with "only" four volumes for now :-).

cjl