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Trailing-Edge - PDP-10 Archives - 6.1_emacs_manuals_1er - manuals/dx20.mem
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                                   DATE: 25 June, 1976
                                   PROJECT: DX20 Bootstrap Loader















                     FUNCTIONAL SPECIFICATION FOR

                   DX20 User Mode Bootstrap Loader

                                DX20LD
DX20 USER MODE BOOTSTRAP LOADER                                 Page 2


1.0  PRODUCT OVERVIEW

This specification describes the bootstrap program to  be  used  under
TOPS20  timesharing  by  the operator to load microcode into the DX20.
This project is part of the  original  DX20-v100  project  which  will
provide  support  for STC tape drives in TOPS20 using the RH20 Massbus
controller.  This bootstrap will also be useful for loading micro-code
into  the  DX20  in  any  applications  beyond  the initial tape drive
support.



2.0  PRODUCT GOALS



2.1  Performance

There are no particular performance objectives for this  product.   It
does not have to be fast, only reliable.



2.2  Support Objectives

Support costs incurred by the field are expected to be  nil  for  this
product.   The  code  is small, and should be close to bug-free before
first ship.



2.3  Environments

This program is intended to be an operator tool,  and  will  run  with
some privileges.



2.4  Reliability Goals

This product will be reliable.  It should not crash or loop.  It  will
check  for hardware failures when through loading the DX20, and report
them at that time.  It should never produce  unusual  results  without
warning the user.



2.5  Non Goals
DX20 USER MODE BOOTSTRAP LOADER                                 Page 3


3.0  FUNCTIONAL DEFINITION



3.1  Operational Description

This program wll have several basic commands, which are differentiated
from each other by switches.  The prompting string will be

     file:

If a file name is specified, the DX20 will be reset, the file will  be
loaded  into  the DX20, verified, and the DX20 will be started.  If /C
is specified as a switch, the DX20 will be cleared before loading.  If
/C is specified without a file name, the DX20 will be cleared only.

If a file name is specified with a /L switch, the file will be  loaded
into the DX20, but no other action will be performed.

If a file name is specified with a /V switch, the contents of the DX20
will  be  compared against the contents of the file (verified), but no
other action will be performed.

If a /S:n switch is specified, the DX20 will be started at location  n
in  the  micro-code.   If  n  is  not  specified, the default starting
address will be used (1).

If a /D:cd switch is specified, DX20 number d on controller  number  c
will  have  the  actions  performed on it specified by the rest of the
command line.

Arbitrary combinations of file name and switches are also allowed.  If
either  /L or /V are specified, only the actions specified by switches
are performed - no defaults.  If /C and/or /S switches  are  specifed,
and  a  file name is specified without the /L or /V switches, the file
will be loaded into the DX20 and verified in  addition  to  performing
the functions specified by the switches.

For a description of the DX20 hardware,  and  the  registers  used  to
cause  the  DX20 to be loaded or cleared, see the DX20 Programmed Data
Channel Specification.
DX20 USER MODE BOOTSTRAP LOADER                                 Page 4


The operation of the file loading process is:

First the DX20 to be operated upon is determined.  If  the  /D  switch
was  not  specified,  all of the RH's will be searched for DX20's.  If
one and only one DX20 is  located,  that  is  the  one  that  will  be
operated  upon.   If  more  than one is found, this error condition is
flagged and no further operations are performed.

The CRAM and working memory are then cleared if required by switches.

Then the low order 16 bits of the first words of the file  are  loaded
sequentially  into the CRAM of the DX20, starting at location 0 of the
CRAM.  This continues until either the end of the file is encountered,
or  a  word containing a -1 is encountered.  If the end of the file is
encountered, loading is completed, and  succeeding  words  are  loaded
into  the  working  memory  of the DX20, starting at location 0 of the
memory.  Only the low order 8 bits of these words contain valid  data.
However, higher order bits will not be checked.  Loading will continue
until the end of the  input  file.   If  the  end  of  the  memory  is
encountered before the end of the file, an error will be typed.

Then the file is rewound, and verified against the  CRAM  and  working
memory, if required by switches.

Upon successful completion of the lading process, the version and edit
number  of  the  micro-code will be typed from location 0 of the CRAM.
The high order 6 bits of this word are the version  number,  and  thre
remaining 10 bits are the edit numer.

The micro processor is then started at the specified starting  address
in the CRAM.  The default starting address is location 1.



3.2  Restrictions

None known yet.
DX20 USER MODE BOOTSTRAP LOADER                                 Page 5


4.0  COMPATIBILITY

No known standards apply



5.0  EXTERNAL INTERACTIONS AND IMPACT



5.1  Users

This program is intended as an operator tool, and will not  be  usable
by users.



5.2  Software Products



5.2.1  Products That Use This Product

The DX20 will not be a useful product without this program.



5.2.2  Products That This Product Uses

TOPS20
DX20 USER MODE BOOTSTRAP LOADER                                 Page 6


6.0  RELIABILITY/AVAILABILITY/SERVICEABILITY



6.1  Failures Within The Product

This product will run with privileges, and it is conceivable that this
product  could  crash a TOPS20 system.  However, in practice a failure
of this product should only cause the DX20 to fail to be loaded.



6.2  Failures Within The Total Environment

This product will attempt to report failures  within  the  DX20  in  a
meaningful manner so that corrective action can be taken.



7.0  PACKAGING AND SYSTEM GENERATION



7.1  Distribution Media

This product will be distributed on a single reel of magnetic tape.



7.2  System Generation

System generation will not  be  required.   There  will  be  only  one
variety of this program.



8.0  DOCUMENTATION

A description of this product will be incorporated into an  Operator's
guide to be distributed with the DX20-v100 package.



9.0  REFERENCES



10.0  APPENDIX