DEC ST506 Interface Adapter Part No 54-17003-01

[js at cimmeri.com]

Here's my personal notes on MFM formatting with the VS2000.   Most was 
gleaned off the Internet; some I revised or improved myself.  Can't 
remember the sources to give credit, sorry.   You can set the interleave.


Example: CDC WREN II #200232
xbnsiz:=54        - number of transfer blocks. All DEC's disks seem to 
use 54, regardless of capacity.
dbnsiz:=31        - = (SURPUN*17) - XBNSIZ
lbnsiz:=78115     - = first, take (Actual Cyls - 1) * SURPUN * 17 - 
(XBN+DBN).  Then calc RBNs and subtract them.
rbnsiz:=340       - = at least 0.2% of LBNSIZ
surpun:=5         - number of heads (surfaces)
cylpun:=925       - actual number of cylinders
wrtprc:=128       - cyl to start write precomp.
rctsiz:=4         - size of Replacement and Caching Table.
rctnbr:=8         - number of copies of the RCT.  DEC disks appear to 
always use 8.
secitl:=1         - sec/sec interleave.  1:1.
stsskw :=2        - sec/sec skew. All drives seem to use 2.
ctcskw :=8        - cyl/cyl skew. Most DEC drives seem to use 8.
mediai :=627327008  - media ID code.  See "VS2000 Formatter.MHT" for 
explanation.


Example: CDC WREN #200052 / 697 x 5 x 17   36mb
XBNSIZ:=54
DBNSIZ:=31
LBNSIZ:=58900
RBNSIZ:=175
SURPUN:=5
CYLPUN:=697
WRTPRC:=348
RCTSIZ:=4
RCTNBR:=8
SECITL:=1
STSSKW:=2
CTCSKW:=8
MEDAI:=627327028

Example: IMI 5012H #200051 / 306 x 4 x 17 WrPre: 214
XBNSIZ:=54
DBNSIZ:=14
LBNSIZ:=20600
RBNSIZ:=72
SURPUN:=4
CYLPUN:=306
WRTPRC:=214
RCTSIZ:=4
RCTNBR:=8
SECITL:=1
STSSKW:=2
CTCSKW:=8
MEDAI:=627327027

Others:
          RD54          RD53        ST4097
        ------        ------        ------
XBNSIZ            54            54            54
DBNSIZ           201            82            99
LBNSIZ        311256        138672        156060
RBNSIZ           609           280           306
SURPUN            15             8             9
CYLPUN          1221?          1020?          1021?
WRTPRC          1221          1020          1024
RCTSIZ             7             5             5
RCTNBR             8             8             8
SECITL             1             1             1
STSSKW             2             2             2
CTCSKW             8             8             8
MEDAI         627327030         627327029         627327029
===============================================================