What can the Stacker API do for you?

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Stacker Note                                     Stacker Note                     

                     

STAC FAX Index #1106                 

                     

                     

                          Stacker API v. 2.0

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What can the Stacker API do for you?


1.  Make your programs more compatible with Stacker.


         Using the API you can now determine if Stacker is

         installed on a system, what version of Stacker is

         running, and which drives in the system are Stacker

         drives.  If the Stacker drives have been swapped, you

         can find out what drives they have been swapped with.

         You can determine if a Stacker coprocessor is installed,

         which coprocessor it is, and the hardware address where

         it is installed.  If a Stacker drive replaces its host

         drive your software can now have direct access to the

         underlying host drive if it needs it.  This and much

         more has been provided to help you enhance your

         product's compatibility.  We think the most common use

         of these features will be in installation programs

         which want to detect Stacker andoptimally configure

         the software that they are installing for a Stacker

         based system.  You'll probably think of lots of other

         things to do with all this information.


2.  Give you direct access to Stacker's compression and

    decompression engines.


         If Stacker software is installed on a PC you can now

         use its high performance compression and decompression

         to improve the performance of your product.  You can

         transmit data in half the time, and store it in half

         the space.  You can reduce memory usage by keeping

         infrequently used data structures in compressed form

         and decompress them when needed.  Speed up your

         software by keeping overlays compressed in EMS or XMS

         and then decompressing them when needed instead paying

         the seek time it costs to read them from disk.  If a

         Stacker coprocessor is installed you'll get even faster

         performance and tighter compression.


         If you are already using one of Stac's LZS221 or DCS221

         compression libraries, you will want to investigate

         using the Stacker API to detect if Stacker is present

         in a system.  If it is, you may want to use the API to

         access Stacker's compression engine which, although

         less general in its interface, provides over fifty

         percent better speed performance over DCS221 or LZS221.


3.  Give you the ability to read compressed data directly

    from a Stacker drive.


         Now you can transfer compressed data directly from a

         Stacker drive, to tape, to backup floppies, across a

         modem, or over a network without having to pay the

         performance penalty of having Stacker first decompress

         the data.  The data format is the same LZS compressed

         data format that is supported by all of our compression

         products.  This means that when you need access to the

         compressed data you can decompress it using our 9703,

         9704, or 9705 compression chips, our LZS221 compression

         libraries (available in 8088, 80386, and 68000 assembly

         as well as C), or the Stacker API.  This is also the

         same compressed data format as the QIC-122 data

         compression standard which is used in quarter inch tape

         drives.


    The version 2.0 Stacker API includes the following:


        - A 78 page manual with examples for each function,

          a section on testing considerations for your

          programs and a section on developing Stacker aware

          installation programs.


        - A C library for all memory models of Borland C

          and Microsoft C.


        - An include file for Assembly language programs.


        - An OBJ file and Pascal unit for Turbo Pascal

          programs.


        - Six Ready to compile and run programs in C plus

          one in Assembly.  These programs include a sample

          Stacker aware installation program, a sample program

          to read files from a Stacker drive in compressed

          form, a sample program that simulates sending a file

          across a modem with and without compression, plus

          several more.  In addition to the source code for

          these programs there are example programs for each

          function in the API.


        - Developer assistance on CompuServe.


Here's what the Stacker API can provide to make your programs

Faster, Smaller and More Compatible with Stacker:


Informational items:


        - Is Stacker installed?

        - Is Stacker hardware or Stacker software being used?

        - The major and minor versions of the Stacker device

          driver.

        - The hardware address of the Stacker coprocessor.

        - The hardware type of the Stacker coprocessor (XT/8,

          AT/16 or MC/16).

        - Is Stacker using EMS for its cache?

        - Is the Stacker driver loaded high (above 640k)?

        - The number of available replaceable Stacker drives.

        - Which drives are which after swapping.

        - Is a drive is Stacked?

        - Is a Stacker drive mounted?

        - Is a Stacker drive an auto-mounting drive or not?

        - Is a Stacked drive write protected?

        - Is a Stacked drive replaced with the host drive?

        - Was a Stacked drive mounted damaged?

        - The number of erased sectors and the number of free

          sectors for a given Stacker drive.  These two figures

          can be used to determine the minimum (physical) space

          available for a Stacker drive.

        - The BPB of a Stacked drive (without having to go to

          disk).

        - The BPB of the host drive of a Stacked drive (without

          having to go to disk).

        - The drive unit number for a Stacked drive.

        - The drive unit number for the host drive of a Stacker

          drive.

        - The stacvol file name for a Stacker drive.

        - The major and minor versions of Stacker that was used

          to create a given Stacker drive.

        - Pointers to the interrupt and strategy routines for

          the host drive of a Stacker drive.  This can allow you

          to access the host drive of a replaced Stacker drive.

        - The number of bits per FAT entry for a Stacker drive.


Compression items:


        - Compress data using the Stacker device driver.

        - Uncompress data using the Stacker device driver.


Drive state manipulation items:


        - Flush the Stacker device driver for all Stacker drives.

        - Unmount Stacker drives.

        - Put a Stacker drive in "host drive mode".  This allows

          you to access the host drive of a Stacker drive

          (including swapped and replaced drives) through a

          drive letter.

        - Take a Stacker drive out of "host drive mode".

        - Set the write-protect status on a Stacker drive in the

          Stacker device driver.

        - Remove the write-protect status on a Stacker drive in

          the Stacker device driver.


Read compressed data items:


        - Read clusters directly from a Stacker drive in

          compressed form.

        - Retrieve the FAT entry for a given cluster on a

          Stacker drive.


For information on how you can purchase the Stacker API, call

Stac Electronics at 619-431-7474, extension 2910,For pricing.

Existing Stac OEM customers who have purchased our 

compression/decompression libraries or chips are entitled to 

the Stacker API free of charge.


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Copyright 1992, Stac Electronics


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