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SECNAT.TXT
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1990-01-06
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Clyde Washburn Inc. SECOND NATUREtm
Pittsford, NY 14534 Accessory ROM Set
===============================================================================
SECOND NATUREtm is an accessory ROM (Read-Only-Memory) product for the IBM PC
and "compatibles" which adds two important features:
o It allows hard disks other than those described in the computer's
original ROM BIOS Fixed Disk Parameter Table to be used as though
they were "Original Equipment".
o It provides user control of the number of floppy drives reported by
the hardware to the Operating System, making it possible to easily
integrate internal 720 and/or 1.44 Mb drives, even on early AT's and
compatibles with no 3.5" Setup option.
SECOND NATUREtm accomplishes these benefits while leaving no resident code!
The parameters it installs are fully compatible with the IBM Technical
Reference, Personal Computer AT, for the most complete Operating System
compatibility possible.
SECOND NATUREtm is compatible with all popular Operating Systems, and allows
multiple DOS Partitions under PCDOS 3.3 (up to 800 Megabytes possible!).
Similar partitioning is expected under Digital Research CDOS XM, Release 5.1.
Disks partitioned in this officially supported manner are always accessible to
the operating system, even from a floppy with only the DOS distribution files;
whereas, aftermarket software-based partitioning schemes can leave you without
even floppy drive access to large sections of your Hard Disk if their
"customized" driver files are damaged.
SECOND NATUREtm includes a built-in Low Level Format & Verify Utility, with the
ability to select the original or any one of up to 26 new Fixed Disk Parameter
Tables for each of two hard disks.
Most AT-type computers have four 28-pin ROM sockets, two of which are usually
occupied by the ROM BIOS. If all sockets are occupied (XT286 & very early IBM
ATs), OR if your computer cannot load Accessory ROMs in the E000 block (Sperry,
Leading Edge, some other AT "clones"), you may use the SECOND NATUREtm I/O
Channel Adapter (sold separately) to locate the ROMs in an I/O slot (8 bit
slots are fine). The I/O Channel Adapter uses the ROM loader routine provided
by compatible BIOS's for common accessories, such as the ROM on EGA Video
Cards, and is therefore very broadly compatible.
The SECOND NATUREtm Low Level Formatter formats, then verifies each track, re-
formatting the track as a "Badtrack" if there is a verify error. This is the
same function provided by the IBM Advanced Diagnostics "Unconditional Format".
Why Control the Number of Floppy Drives?
PCDOS and MS-DOS have always included provision for Logical Drives, the mapping
of one Physical Drive to two (or more) Drive Designators. The most common
example is a single floppy drive PC, where that drive functions as both A: and
B: Logical Drives, and allows easy copying of both files and disks.
On the PC-AT, however, this concept has not been well implemented: when a 360k
floppy is installed as B:, the 1.2 Mb format now exists only on A:, and file
copies to another 1.2 Mb disk can only be done by installing another Logical
1.2 Mb drive with DRIVER.SYS.
Worse, when a 3.5", 720K drive is installed in the B: location neither 1.2 Mb
nor 360K floppies can be easily file-copied to the same format, unless
DRIVER.SYS is used. But even then B: drive is ill-defined: it will not format
720K, 3.5" disks properly because it thinks it's a 1.2 Mb disk! The DRIVPARM
option in CONFIG.SYS is not always a solution, as it has never been officially
part of PCDOS (only MS-DOS 3.2) and it doesn't work in all AT's -- some BIOS
versions "forget" the redefinition of B: after other disks are accessed.
The solution when installing a 3.5" drive in an XT is to set the dip-switches
to report only ONE floppy drive, which then retains it's Logical A: and B:
designations, then use two DRIVER.SYS entries in CONFIG.SYS to create two
(neatly consecutive) Logical Drive Designators for the 3.5" drive. This has
been impossible on the AT: it reports the number of actual drives installed --
until now! SECOND NATUREtm allows the number of floppies reported to be
controlled, allowing the clean and elegant XT solution to be used on the AT as
well.
===============================================================================
DISTRIBUTED BY: Geneva Enterprises
0804 Waterloo-Geneva Rd
Waterloo, NY 13165
315-539-5083
Technical Inquiries (only) to Clyde Washburn, Compuserve 70305,1211.