Re: VaxStation 2000 and MFM Drive

[Tom Ivar Helbekkmo <tih%hamartun.priv.no@localhost>]

romanis%gmx.ch@localhost writes:

> Are there known compatibility issues with non-dec MFM drives and
> booting?  maybe i did an error in specifing the disk as an RD51?

For what it's worth, here's a USENET posting of my notes from back when
I played with VS2000 machines and MFM disks:

Newsgroups: vmsnet.pdp-11
Subject: Re: Magic RD-54 and RD-52 numbers
From: Tom Ivar Helbekkmo <tih+nr%eunetnorge.no@localhost>
References: <pan.2004.03.23.18.40.00.775561%SPAM.vt.edu@localhost>
Date: Fri, 26 Mar 2004 09:50:42 +0100
Message-ID: <86k718vvod.fsf%athene.i.eunet.no@localhost>

Christopher McNabb <cmcnabbNO%SPAM.vt.edu@localhost> writes:

> Does anyone know the magic numbers to enter into Test 70 on a
> uVax-2000 to properly format an RD-54 and an RD-52 that are not
> recognized as being such due to being formatted by some other (PC)
> system?

Here's what I've figured out about the TEST 70 parameters so far --
this is for the RD52 drive, by the way:

     xbnsiz :=54         [enter the number of transfer blocks]
     dbnsiz :=82         [enter the number of diagnostic blocks]
     lbnsiz :=69256      [enter the number of logical blocks]
     rbnsiz :=240        [enter the number of replacement blocks]
     surpun :=8          [enter the number of surfaces per unit]
     cylpun :=512        [enter the number of cylinders per unit]
     wrtprc :=512        [enter the write precompensation cylinder]
     rctsiz :=4          [enter the size of the revectoring control table]
     rctnbr :=8          [enter the number of copies of the RCT]
     secitl :=1          [enter the sector interleave]
     stsskw :=2          [enter the surface to surface skew]
     ctcskw :=9          [enter the cylinder to cylinder skew]
     mediai :=627327028  [enter the MSCP media ID]

The total disk size is, of course, the number of cylinders (cylpun)
times the number of surfaces (surpun) times the number of sectors per
track (17).  Then, this gets used as follows, although I don't know
what the actual order of the special allocations on disk are:

- The number of transfer blocks (xbnsiz) is always 54.
- The number of diagnostic blocks (dbnsiz) should be calculated so
  that xbnsiz + dbnsiz = one whole cylinder.
- The number of logical blocks (lbnsiz) includes the revectoring
  table, so that the visible number of blocks that can be used by
  the OS = lbnsiz - (rctsiz * rctnbr).
- The transfer blocks and diagnostic blocks are allocated outside
  the logical block area, as are the actual replacement blocks, so
  lbnsiz = physical size of disk - xbnsiz - dbnsiz - rbnsiz.

These are the magic numbers for a bunch of different disks:

ESE20: 625685140
ESE25: 625685145
RA60:  581177404
RA70:  627314758
RA71:  627314759
RA72:  627314760
RA80:  627314768
RA81:  627314769
RA82:  627314770
RA90:  627314778
RA92:  627314780
RC25:  543436825
RC25F: 543437593
RD31:  627327007
RD32:  627327008
RD33:  627327009
RD51:  627327027
RD52:  627327028
RD53:  627327029
RD54:  627327030
RF30:  577003550
RF31:  577003551
RF71:  577003591
RF72:  577003592
RF73:  577003593
RFH31: 577004575
RFH72: 577004616
RFH73: 577004617
RRD40: 627384872
RRD50: 627384882
RX18:  627408914
RX33:  627408929
RX35:  627408931
RX50:  627408946
SVS00: 560425344

-tih
-- 
It doesn't matter how beautiful your theory is, it doesn't matter how smart
you are. If it doesn't agree with experiment, it's wrong.  -Richard Feynman