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sstt -- Device Driver


The /ddeevv/rrsstt*  devices provide access to the  Archive SC-400 streaming tape
controller.   Each entry  is assigned  major device number  12, and  may be
accessed as a character-special device.

The  sstt tape  driver  handles one  0.25-inch  streaming-tape drive.   Minor
device 0  requests allocation  of a 256-kilobyte  tape cache and  should be
used unless the system has  minimal memory (e.g., less than 640 kilobytes).
Minor devices  1 through 127 request  allocation of a tape  cache of one to
127 kilobytes.   These devices normally  rewind the tape  during the close;
adding 128 to a minor-device number specifies non-rewind on close.

For an interface  to be accessible from the COHERENT  system, a device file
must be  present in  directory /ddeevv with  the appropriate type,  major, and
minor device numbers, and permissions.  The following gives an example form
of the command mmkknnoodd to creates a special file for a device:

/etc/mknod /dev/rst256 c 12 0
/etc/mknod /dev/nrst256 c 12 128

Tape-oriented commands under COHERENT (e.g., ttaarr) normally the disk devices
to store their output.  The following sample commands associate the generic
interface with the Archive streaming tape driver:

/bbiinn/llnn -ff /ddeevv/rrsstt225566  /ddeevv/rrmmtt
/bbiinn/llnn -ff /ddeevv/nnrrsstt225566 /ddeevv/nnrrmmtt

Depending on the  amount of memory available, you may  wish to restrict the
amount of memory used to buffer tape data.  This may be done by linking the
appropriate /ddeevv/rrsstt entry  to /ddeevv/rrmmtt.  For example, /ddeevv/rrsstt6644 allocates
64  kilobytes during  tape transfer  whereas  /ddeevv/rrsstt3322 allocates  only 32
kilobytes.

_H_a_r_d_w_a_r_e

The following  kernel variables define the  hardware interface to streaming
tape.

SSTTIIRRQQ     Specify the interrupt vector (default, 3).

SSTTPPOORRTT    Specify the input/output port (default, 0x200).

SSTTDDMMAA     Specify the DMA channel (default, 1).

Should these parameters conflict with other system hardware, you should use
the  command /ccoonnff/ppaattcchh  to  rebuild the  kernel  appropriately.  See  the
Lexicon article on hhss for sample commands.

_F_i_l_e_s
/ddeevv/rrsstt* -- Auto-rewind character-special file
/ddeevv/nnrrsstt* -- Non-rewinding character-special file
<ssyyss/mmttiiooccttll.hh>-- Tape iiooccttll commands

_S_e_e _A_l_s_o
ddeevviiccee ddrriivveerrss, ttaarr

_N_o_t_e_s
As delivered, the Archive tape controller uses interrupt vector 3.  If this
interrupt  is to  be  used, then  the  COHERENT kernel  must be  configured
without the second serial line driver (e.g., /ddeevv/ccoomm22*).

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.