CCDISK            COPYRIGHT horio shoichi 1995             CCDISK



NAME
     ccdisk.exe - dos reentrant SCSI disk driver

SYNOPSIS
     device=ccdisk.exe [ takeover ] [ concurrency=max-concurrency
     ] [ irq_array=array-of-irqs ]

COMMAND LINE RULES
     Command line has following rules

     -    Operands consist of options and terminating ';'  (semi-
          colon). Except for ';' , the order is unimportant.

     -    The character ';' (semicolon) terminates command  line.
          Operands after the character are ignored.

     -    All operands are case sensitive, and generally must  be
          in  lower  case.  For lines in config.sys, operands are
          converted to lower case.

     -    Alphabetic part of an option can be abbreviated down to
          one  character.   For example the delete option has the
          syntax d[e[l[e[t[e]]]]]].

     5)   The character '/' can be placed anywhere ' ' (the white
          space) can be placed.

DESCRIPTION
     Ccdisk.exe is a device driver loaded  from  config.sys  line
     which  handles  SCSI disks that do not use BIOS int13 inter-
     rupts to communicate with.  Instead,  ccdisk.exe  uses  ASPI
     (Advanced  SCSI  Programming  Interface)  for its communica-
     tions.

     It must be loaded after ASPI and before concache.exe.

     If concache.exe is not loaded, ccdisk.exe works exactly like
     any  other  block device driver.  It accepts driver requests
     from dos serially and performs each of the requests  to  the
     complesion.

     If concache.exe is loaded, concache.exe intercepts  all  dos
     requests to ccdisk.exe and routes the requests to ccdisk.exe
     described as above if necessary.  If  the  request  is  gen-
     erated by concache.exe then it directly far calls ccdisk.exe
     function entry that performs io asynchronously.

     Option concurrency= specifies the maximum number of  devices
     to  work  concurrent.   If this option is not specified, the
     maximum concurrency is set to about the half the  number  of
     detected units.




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     Important.  This   concurrency   value   is   retrieved   by
     concache.exe  and concache.exe tries to set aside stack area
     (about 500 bytes) and io buffer area (minimum 512 bytes. see
     concache.txt.)  for  each  device  to  let  them  work  con-
     currently.  If conventional memory or upper memory block  is
     precious, use rather conservative concurrency= value.

     Option takeover tells ccdisk.exe  to  take  over  SCSI  disk
     operations  from  dos  io.sys  device driver and perform the
     operations concurrently with other devices and user/dos pro-
     grams.

     Important. If SCSI disks are configured to use  BIOS  inter-
     face,  since  BIOS  notifies device interrupt conditions via
     (also BIOS) int159[01]00  interrupts  to  tell  only  device
     types,  it  is  impossible  to handle them concurrently, nor
     discriminate them from non-SCSI devices.  To configure  SCSI
     disks   not   to   use   BIOS,  see  respective  SCSI  board
     manufacturer's manuals.

     However, if only one SCSI disk unit exists and no other type
     disks  are configured, using ccdisk.exe is not very strongly
     advantageous, since in this case  BIOS  int159[01]00  defin-
     itely designate the unit.

     Option irq_array= specifies irqs used for each host  adapter
     in  hexadecimal array.  The array is composed of concatenat-
     ing hexadecimal value of irq number.  Note specifying irqs 0
     (timer),  1  (keyboard),  6 (floppy), 8 (real time clock), 9
     (redirected interrupts), and 0xe (hard  disk)  are  silently
     ignored.   For  example,  irq_aray=b0c means host adapters 0
     uses irq 11, adapter 1 uses none, and adapter 2 uses irq 12.
     If  this  option  is  unspecified,  then irq range 8 - 15 is
     searched and those not  pointing  into  ROM  segment  0xf000
     space are considered candidate SCSI irqs.

     Important. If non-SCSI device is hooked on the  searched  by
     default  or specified irq, the interrupts on the device will
     have a small delay on each interrupt.  (but with no  practi-
     cal harms, if the interrupt is not very timing sensitive).


SEE ALSO
     cctame.txt,    concache.txt,    floppies.txt,    eqanda.txt,
     intro.txt,
     respective SCSI board manufacturer's manual


FEATURES
     Current implementation has following restrictions

     -    Physical block size must  be  512  bytes,  and  logical



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          block  size  (given  by  BIOS  parameter block) must be
          either 512, 1024, or 2048 bytes.

     -    Only dos compatible partitions, type 1,  4,  5,  6  are
          recognized.

     -    No removable media, such as magneto-optical,  are  han-
          dled.

     -    Ioctl are not implemented.

     Irqs should have been retrievable via ASPI.











































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