FIELD SERVICE SOFTWARE ASSISTANCE BROCHURE
O S - 8
Prepared by:
Rick Moore
INTRODUCTION
This is a reference document for Field Service use in
diagnosing system problems. The information presented in this chapter
is extracted from various OS-8 reference manuals and literature which
are listed in the appendix.
It is not intended to be a course on OS-8 or a substitute for
standard DEC software manuals. However, the topics presented here are
some of the more commonly used features and some of the commands that
should help you to better serve your customer through an enhanced
knowledge of his OS-8 operating system.
It is strongly recommended that you be extremely careful using
your customer's software as a little knowledge is a dangerous thing.
If you do work on a customer's files, be sure to use copies of his
system only. Tell him what you feel the problem is and let him take
any corrective action.
OS-8 consists of an executive and library of system programs
which reside on a mass storage device called a "system device". This
could be a disk, dectape or floppy unit. The executive supervises the
overall program processing and consists of the following four major
components:
- Keyboard monitor ( KMON )
- Command Decoder ( CD )
- Device Handlers
- User Service Routine ( USR )
The Keyboard Monitor provides communications between the user
and the OS-8 Executive. The root segment of the monitor resides
perminently in memory and occupies 256 words. Commands from the
console terminal are interperted and whenever needed, the Command
Decoder, USR, KMON, and ODT are brought into memory in a series of
overlays while the contents of the memory used is swapped out to the
system scratch area. In this manner it is possible to run a baseline
system in only 8K words of memory.
The commands that are executed directly from the KMON are:
ASsign - assigns a new, user defined device name to a
perminant device.
DEASsign - restores perminant device names
GET - loads core image files into memory from a
device
START - starts execution of a program already in
memory
RUn - loads core image (.SV) files into memory from
a device and starts execution
R - loads core image (.SV) files into memory from
the SYStem device and starts execution
SAve - creates core image programs on a device
ODt - invokes the Octal Debugging Technique
DAte - sets / prints the system date
The Command Decoder is called when a system program needs
additional information from the operator concerning files to be acted
upon or devices to be used. You are in the Command Decoder whenever
the prompt character "*" is issued.
Understanding the Command Decoder line format is probably the
most important step to successful usage of the OS-8 Operating System.
It is as follows:
*OUTDEV:OUTFIL.EX<INDEV:INFILE.EX,INFILE.EX/SW1/SW2=N
... to translate ...
OUTDEV: - the output device (SYS:,RKB0:,DTA0:,LPT:)
OUTFIL.EX - the name of the output file and it's extension
INDEV: - the input device
INFILE.EX - the name of the input file and the extension
SW? - an optional switch ... differint for each
program
=N - numerical value (ie: in direct =N# of
columns)
There may be 0-3 input files, 0-9 output files, 0-3 option
switches, depending on the requirements of the individual program. In
several programs, it is not necessary to specify every detail ...
certain programs have default values for devices, switches, etc. The
only way to be sure of this is to know the program you are working
with.
Again, the value of learning the command decoder format cannot
be overstressed ... the same basic format is used thoughout DEC
software. (ie: RT-11, RSTS, etc.)
Device Handlers are subroutines which handle data transfer to
and from peripheral devices. Device handlers for the particular
hardware system you are using are activated by the program "BUILD".
These subroutines are then available to all OS-8 programs. It is
through the use of device handlers that a sort of "device
independence" is acheived.
The USR is a collection of subroutines that perform operations
of opening and closing files, loading device handlers, program
chaining, and calling the CD. The USR provides these functions not
only for the system itself, but for any programs running under OS-8.
INITIALIZING OS-8
Mount the OS-8 System on the appropriate hardware and execute
the bootstrap. This may be as simple as pressing a "BOOT" button or
require a toggle-in program from the operator's console. Various
bootstraps are listed in the appendix.
After the bootstrap is executed, the monitor will print a dot
"." on the console. At this point, KMON is active and the system is
ready to accept one of the monitor level commands listed on page 1.
CCL
The Concise Command Language ia a means of providing an easy to
understand "English-like" command interface between the operator and
the monitor. It translates the commands, chains to the appropriate
system programs, passes arguments and filespecs, and starts execution.
Any CCL command can be simulated by typing the necessary monitor and
CD responses manually. For example:
.DIR is equivalent to .R DIRECT
*TTY:<SYS:/E=2
.COPY RXA1:<RKA0: is equivalent to .R FOTP
*RXA1:*.*<RKA0:*.*
The use of CCL is optional in OS-8; manditory in OS-78. This is
because you cannot normally access monitor level commands in OS-78.
There is a way around this; by typing ".SET SYS OS8" it is possible to
turn on this attribute.
GETTING DIRECTORIES
.DIR - types directory of system device on the
console
.DIR-L - prints directory of system device on line
printer
.DIR RKB0:-L - prints directory of device RKB0 on line
printer
SET
The program "SET.SV" is called by the ".SET" CCL command and
can be used to modify some of the attributes of the various device
handlers. Some useful ones are:
.SET SYS OS8 - allows monitor level commands in
OS-78.
.SET SYS OS78 - normal OS-78 mode; CCL commands only
.SET SYS INIT - causes the command file "INIT.CM" to
be executed upon boot-up.
.SET SYS INIT [cmd] - causes the command [cmd] to be
executed upon boot-up.
.SET SYS NO INIT - negates the above
.SET LPT LA78 - allows PDP-8A (M8316) parrallel port
as controller for LA-180 (device
code=0570)
.SET LPT LA8A - restores LPT to normal 0660 device
code
.SET TTY SCOPE - causes a rubout to actually erase the
character from the screen.
.SET TTY NO SCOPE - causes the rubout to echo the
character/slash combination for
hardcopy terminals.
.SET TTY PAUSE - causes the terminal to pause every
"height" lines for ease of reading.
.SET TTY HEIGHT 24 - tells the handler the screen has 24
lines
.SET TTY WIDTH 80 - allows 80 character width to VT52
screen
*** WARNING ***
The command ".SET SYS NO INIT" must be given before attempting
to use the "BUILD" program, since execution of the "INIT.CM" file or
any CCL command will cause the previous contents of memory and the
system scratch area to be altered. Also, since the process of
executing this file may entail several overlays, the usefullness of it
on any media except disks or diskettes is questionable.
OS-8 FILES
There are three standard types of OS-8 file formats used by
OS-8 and associated system programs; ASCII, Binary and Core Image
(.SV).
ASCII and Binary files are packed three characters to every two
12 bit words as follows:
-----------------------------------------------
| | |
Word 1 | Char. 3 | Character 1 |
| (bits 0-3) | (bits 0-7) |
| | |
-----------------------------------------------
| | |
Word 2 | Char. 3 | Character 2 |
| (bits (4-7) | (bits 0-7) |
| | |
-----------------------------------------------
0 - 3 4 - 11
In Binary files, the binary data must be preceded by one or
more frames of leader/trailer code (ASCII 200 code). The first
character must be either 100-177 octal (origin setting for absolute
binary files), 240-257 octal (a COMMON declaration frame for
relocatable binary files), or 300 octal which is an origin setting.
The end of binary data is one or more frames of leader trailer code.
ASCII and Binary files are terminated by a CTRL/Z code (ACSII 232).
A Core Image file consists of a header followed by the actual
core image. The header is called the Core Control Block (CCB). It
consists of first 128 words of the first block (256 words) of the
file. The CCB is a table of information that contains the length of
the file, the program's starting address, and the Job Status Word
(JSW). The CCB for a program at the time it is loaded into core is
always saved in words 200-377 (octal) of block 37 on the system's
scratch area. It is placed there by the GET or RUN operations or by
the ABSLDR program. This information is then used when performing a
SAVE without arguments.
FILE NAMES and EXTENSIONS
Files are referenced symbolically by a name of up to six
characters followed, optionally, by a period and a two character
extension. The extension to a file name is generally used to type the
files according to their formats or defaults to particular system
programs.
In most cases, the user will want to conform to the standard
file name extensions established for OS-8. If the extension is not
specified for a files, some system programs will append an assumed
extension by default. This default extension can be overidden by
stating the extension in the CD line explicedly.
The most common OS-8 standard default extensions are:
SV - core image programs
BN - binary programs
PA - PAL8 assembly language sources
BA - BASIC source files
BI - BATCH control files
SY - system heads
DG - diagnostic program **
BX - DECX8 exercisor modules **
X8 - customised DECX8 system exercisor **
** refers to psuedo standards imposed by the New England
District PDP-8 Diagnostic System.
FILE MANIPULATIONS
Files can be transfered between OS-8 devices by using either
"FOTP.SV" (File Oriented Transfer Program) or "PIP.SV" (Peripheral
Interchange Program) or the CCL commands that call them. These
commands and their uses are:
COPy - copies files from one device to another
DELete - deletes files from a device
LIst - lists an ASCII files on the LPT
REName - changes the name of a file in the directory
SQuish - eliminates all empty and deleted files on a
device
TYpe - types an ASCII file on the console terminal
ZERO - zeroes the directory of a device, deleting
all existing files on that device
For example, to copy file FOO.PA from RXA1: to RKB0:
.COPY RKB0:<RXA1:FOO.PA
( note the similiarity between this and the format of
the Command Decoder Line on page 2.)
To copy an entire device using PIP and FOTP type:
.R PIP first transfer the system heads
*RKA1:<RKA0:/Y/Z
*RKB1:<RKB0:/Y/Z
.R FOTP now all the files
*RKA1:<RKA0:*.* using wildcard transfers
*RKB1:<RKB0:*.*
For floppies, it is easier since the program "RXCOPY.SV" or the
CCL command ".DUPLicate" will copy the entire device.
SYSTEM HEADS
The "/Y" option of PIP.SV can be used for system head
manipulation. A system head is 50 blocks long and is located at the
beginning of the system device. It contains the system bootstrap, the
monitor, and all it's overlays. System heads are sometimes stored as
files on a device for ease of use with the extension ".SY".
To move a system head:
.R PIP
*RKA1:<RKA0:/Y
if "RKA1" is a virgin device, a skeleton directory must be
created, so type:
*RKA1:<RKA0:/Y/Z
USING WILDCARDS
Certain commands allow wildcards in the file name
specifications. These commands are COPY, DELETE, DIRECT, LIST, RENAME,
and TYPE.
Wildcards allow a filename or extension to be totally replaced
with an asterisk (*) or partially repalced with a question mark (?).
Wildcards are particularly useful when doing multiple file transfers.
This is illustrated in the following examples:
TEST1.* - all files with the name TEST1 and any
extension
*.BN - all files with a BN extension and any name
*.* - all files with any name and any extension
TEST2.B? - all files with the name TEST2 and any
extension starting with a B
TES??.PA - all files with a PA extension and any name
from 3 to 5 characters beginning with TES
the asterisk amd question mark can be used together
???.* - all files with any extension and with file
names of three characters or less
BUILD
The program "BUILD.SV" is the system generation program for
OS-8 which allows the user to:
1. Maintain and update device handlers in an existing OS-8
system.
2. Add device handlers to a new or existing system.
3. Change the system characteristics to reflect hardware
modifications.
Device handlers are supplied with the OS-8 system and are in
the format of Binary (.BN) files.
To run the Build program, type:
.RUN SYS BUILD
NOTE:
It is important that the user specify the "RUN" command,
rather than the "R" command when loading BUILD into core.
This will allow the CCB to be stored on the system scratch
area for use with the SAVE command!
Also, since the system scratch area is used at times when
the "INIT.CM" file is executed, it is imperative that the
command ".SET SYS NO INIT" be given prior to beginning the
BUILD process. After the program is SAVEd, ".SET SYS INIT"
can be reinstituted.
This matter cannot be overemphisized ... SAving "BUILD"
without these precautions will appear to work and the
system will boot without failure, however, the next time
BUILD is run, it will not work! This is because the proper
CCB parameters will have been lost.
RUNNING BUILD
Changing a system's parameters can be a complicated procedure
with too many variables to be explained in this document. For complete
instructions on BUILD, see the appropriated OS-8 Manual.
- DEVICES
Some of the devices that are available in the OS-8 system are:
SYS: - the system device
DSK: - the default device (usually SYS:)
RKA0: - "A" side of RK05 drive #0
RKB0: - "B" side of RK05 drive #0
TTY: - console teletype
LPT: - line printer
LQP: - letter quality printer (Diablo)
PTR: - paper tape reader
PTP: - paper tape punch
DTA0: - dectape drive #0
DTA1: - dectape drive #1
RXA0: - RX01 floppy drive #0
RXA1: - RX01 floppy drive #1
RL0A: - RL01 area "A" drive 0
RL0B: - RL01 area "B" drive 0
RL0C: - RL01 area "C" drive 0
FUTIL
The OS-8 File UTILity program was orginally developed by Jim
Crapuchettes of Menlo Computer Associate,Inc., Menlo Park, CA. It is
now included within the OS-8 Extension Kit after release V3D, and is
also contained on the New England District PDP-8 Diagnostic System
after release V8.04.
FUTIL enables a user to examine and modify the contents of mass
storage devices, including the SYStem device, and is therefore as
dangerous as it is useful! It can be used to recover damaged files,
repair destroyed directories, patch programs on the mass storage
device, and check for bad blocks on the device.
It is this last feature that is particularly useful to us in
Field Service as we often have questions concerning the validity of a
customer's disk or diskette. The following procedure can verify this:
.R FUTIL
SET DEVICE RXA0 floppy drive 0 is the target
device
SCAN 0-755 scans the 756 (octal) blocks on
the device
EXIT returns to OS-8
If any bad blocks were encountered, the program would report
BAD BLOCK nnn where "nnn" was faulty
The cause of this could be due to either a bad CRC character
due to blown data (can be recopied) or blown format (device must be
reformatted). In the case of floppies, the later condition is fatal as
they cannot be reformatted.
FUTIL can be used to scan devices regardless of their program
contents, for example, OS-8, COS 300, or any customer written file
structure can be scanned, as long as standard sector format is used.
to SCAN an RK05 Disk:
.R FUTIL
SET DEVICE RKA0 or RKA1, etc.
SCAN 0-6257 there are 6260 blocks
SET DEVICE RKB0 now the other side
SCAN 0-6257
EXIT
.
NOTE:
At this time, a note on the "sides" of a disk is in
order. The RK05 is broken up into two (2) logical
devices called "RKA0" and "RKB0" as the RL01 is broken
into three (3) devices called "RL0A", RL0B", and "RL0C"
by OS-8. This is because of the system's inability to
address the entire disk and the limited number of
entries the directories can hold.
These "sides" are actually not physical sides (who ever
heard of a three sided RL01), but refer (on the RK05)
to the first 6260 sectors as "RKA0" and the remaining
6260 sectors as "RKB0". A look at the hardware shows
that after the sector counter overflows (at 16 sectors)
the heads switch to the other surface. After the sector
counter overflows again, the heads switch back and then
the cylinder address increments. Thus RKA0 is on the
outer tracks of the disk and RKB0 is on the inner
tracks.
Feel free to contact me, David Gesswein djg@pdp8online.com with any questions, comments on the web site, or if you have related equipment, documentation, software etc. you are willing to part with. I am interested in anything PDP-8 related, computers, peripherals used with them, DEC or third party, or documentation.
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