Trailing-Edge
-
PDP-10 Archives
-
AP-4178E-RM
-
swskit-documentation/abaud.mem
There are no other files named abaud.mem in the archive.
DOCUMENT: RAB-77-003-00-S
DATE: June 30, 1977
PROJECT: RSX-20F/TOPS-20 Release 3
CHARGE NUMBER: 64-08507
PRODUCT ID: QT010
PRELIMINARY FUNCTIONAL SPECIFICATION FOR
RSX-20F AUTO-BAUD DETECTION FOR TOPS-20 RELEASE 3
AUTHOR: Roland Belanger
ISSUED BY: __________________________________
Supervisor
__________________________________
Project Leader
APPROVED BY: __________________________________
Development Manager
__________________________________
Product Manager
__________________________________
Product Manager
REVIEWED BY: __________________________________
Software Documentation Manager
__________________________________
Software Reliability Manager
__________________________________
HOSS Manager
Preliminary Functional Specification for RSX-20F Auto-Baud Detection Page 2
COPYRIGHT (C) 1977, 1978 DIGITAL EQUIPMENT CORPORATION
The software described in this document, including but not
limited to instruction execution times and operating speeds, is
for information purposes only. All such material is subject to
change without notice. Consequently DIGITAL makes no claim and
shall not be liable for its accuracy.
The software described is furnished to the purchaser under a
license for use on a single computer system and can be copied
(with the inclusion of DIGITAL's copyright notice) only for use
in such system, except as otherwise may be provided in writing by
DIGITAL. Ownership of, or title to, the software described in
this document is not transferred.
DIGITAL assumes no responsibility for the use or reliability of
its software on equipment that is not supplied by DIGITAL.
Preliminary Functional Specification for RSX-20F Auto-Baud Detection Page 3
1.0 PRODUCT OVERVIEW
1.1 PRODUCT ABSTRACT
RSX-20F/TOPS-20 Auto-Baud Detection is an extension of the
current DH11 Terminal Service (DC20) which will allow system
independent, automatic selection of the initial terminal
speed for dial-up DC20 lines upon connection to the
RSX20F/TOPS-20 System. This feature is similar to that
which is currently supported by the DN76 and DN8X
Communication Concentrator series under TOPS-10, with the
exception of resynchronization on framing errors. With this
feature, a DC20 dial-up line may be connected to a TOPS-20
System with a terminal speed of 300, 150, or 110 Baud. Once
connected, the user may then alter his terminal speed via
the normal "TERMINAL SPEED" Command to the TOPS-20
Executive.
The current TOPS-20 System Configuration File, "CONFIG.SYS",
must be altered to include the keyword "AUTO" in the
specification for DC20 lines which are to be declared as
Auto-Baud lines.
1.2 MARKETS
There are no specific markets for the RSX-20F Auto-Baud
Detection feature, other than the TOPS-20 User community in
general.
1.3 COMPETITIVE ANALYSIS
The Auto-Baud detection functionality planned is very
similar to that provided by the DN76 and DN8X series under
TOPS-10 (Q.V.).
1.4 PRODUCT AUDIENCE
The End-User of the RSX-20F/TOPS-20 Auto-Baud detect feature
is the normal timesharing user on a TOPS-20 system.
2.0 GOALS
The major goal of the RSX-20F Auto-Baud detect project is to
provide the functionality required for a clean, fast, and
reliable means by which a remote DC20 line may connect to a
TOPS-20 system at any one of the following automatically selected
symmetrical line speeds:
Preliminary Functional Specification for RSX-20F Auto-Baud Detection Page 4
1. 110 Baud.
2. 150 Baud.
3. 300 Baud.
It is also a goal to design and implement the RSX-20F Auto-Baud
facility in such a manner that the possibility of local DC20
lines being Auto-Bauded at a later date is not precluded.
2.1 PERFORMANCE
The RSX-20F Auto-Baud detection feature will allow the
RSX-20F Data Line Scanner (DC20) to automatically determine
and set the transmit and recieve speed of any given DC20
line with only one pass through that section of code,
provided that the DC20 line is operating withing the
specified range of symmetric connect speeds allowed. The
operation of the RSX-20F Auto-Baud detection feature will be
transparent to a normal TOPS-20 timesharing user and totally
independent of the Operating System running in the KL.
2.2 SUPPORT OBJECTIVES
The RSX-20F Auto-Baud detect feature will require little or
no additional support planning. The normal system
documentation supplied with the system will be adequate for
the totality of installations.
2.3 ENVIRONMENTS
2.3.1 HARDWARE ENVIRONMENT -
The RSX-20F Auto-Baud detect feature requires a normal
PDP-11/40 Front-End equipped with at least one DC20
16-line group consisting of a DH11 Programmable
Asynchronous Serial Line Multiplexer and an associated
DM11BB Modem Control Multiplexer. The terminal devices
connected to the DC20 lines are assumed to be LA36
hard-copy terminals running at 300 Baud over a DF01 or
equivalent modem.
Preliminary Functional Specification for RSX-20F Auto-Baud Detection Page 5
2.3.2 SOFTWARE ENVIRONMENT -
The RSX-20F Auto-Baud detect feature will operate under
RSX-20F version VB10-00 or beyond and TOPS-20 Release 3
or beyond. The System Configuration File,
"CONFIG.SYS", must be altered to include the keyword
"AUTO" in the specification for those DC20 lines which
are to be declared as Auto-Baud lines.
2.4 RELIABLITY GOALS
The RSX-20F Auto-Baud detect feature will be extensively
tested in as many different configurations and environments
as possible in order to assure the greatest degree of
reliability possible.
2.5 NON GOALS
The Non-Goals of the RSX-20F Auto-Baud Project are listed
below:
1. To provide Auto-Baud detection support for local
DC20 (DH11) lines.
2. To provide Auto-Baud detection support for IBM 2471
type terminals (134.5) baud.
3. To provide Auto-Baud detection support for 200 Baud
lines or lines running at a line speed greater than
300 Baud.
4. To provide Auto-Baud detection support for
assymmetrical line speeds, i.e. 150 Baud recieve,
300 Baud transmit, etc..
5. To provide support for resynchronization on framing
errors.
3.0 FUNCTIONAL DEFINITION
NOTE
While both the Product Requirement and Auto-Baud Protocol
documents define the Auto-Baud attribute of a DC20 line
to be dependent on the Remote attribute of that line,
this Functional Description considers these two line
Preliminary Functional Specification for RSX-20F Auto-Baud Detection Page 6
attributes as equally significant and independent.
3.1 OPERATIONAL DECSRIPTION
The operation of the RSX-20F Auto-Baud detect feature
consists of three phases:
1. Auto-Baud line specification.
2. Auto-Baud line speed initialization.
1. Hardware line speed setting.
2. Software line speed setting.
3. Auto-Baud line speed termination.
Each phase of operation is described below.
3.1.1 AUTO-BAUD LINE SPECIFICATION
At Primary Protocol start-up, the TOPS-20 system will
send a stream of messages to the RSX-20F Front-End in
which the TOPS-20 system will declare which of the DC20
lines are to be considered Remote and/or Auto-Baud
lines. Any given DC20 line may possess any combination
of these attributes associated with it, or none at all.
These messages will be transmitted from the TOPS-20
system to the RSX-20F Front-End via the
"Here is Line Speed" message in the the Queued
Protocol.
Upon reciept of a message which declares a DC20 line to
be an Auto-Baud line, the RSX-20F Front-End will ignore
the accompanying line speed and set the line to 300
Baud, for both transmit and recieve, and declare that
line to be an Auto-Baud line.
In the event of an RSX-20F requested reload of the
TOPS-20 system, the Front-End will transmit the Line
Speed, Remote, and Auto-Baud line data, for lines so
designated, in response to the
"Request for Initial-Status" Queued Protocol message.
Preliminary Functional Specification for RSX-20F Auto-Baud Detection Page 7
3.1.2 LINE SPEED INITIALIZATION
Upon receipt of a Ring Interrupt, the DC20 (DM-11-BB)
Interrupt Routine (ISR) will declare an Auto-Baud line
to be in the "Auto-Baud Wait" (ABW) state.
When the DC20 (DH11) Interrupt Service Routine (ISR)
recieves a character from a DC20 line, it will check
whether or not that DC20 line is in the
"Auto-Baud Wait" state. If not, the Interrupt Service
Routine will process the character as normal input to
the TOPS-20 system.
If the DC20 Interrupt Service Routine determines that
the line is in the "Auto-Baud Wait" state, it will
attempt to match the bit pattern in that DC20 line's
reciever buffer with that which is associated with a
particular line speed. The bit pattern match will be
attempted for either a Control-C character (Ascii 003),
with even or odd parity, or a Carriage-Return character
(Ascii 015), with even or odd parity. If the match is
successful, both the transmit and recieve speeds for
that DC20 line will be set to the line speed associated
with the bit pattern recieved, and the line removed
from the "Auto-Baud Wait" state. The Line Speed
configurations will be set as follows:
1. 110 Baud, 1 Start Bit, 1 Parity Bit, 2 Stop
Bits.
2. 150 Baud, 1 Start Bit, 1 Parity Bit, 1 Stop
Bit.
3. 300 Baud, 1 Start Bit, 1 Parity Bit, 1 Stop
Bit.
The RSX-20F Front-End will then inform the TOPS-20
Executive of the line connection by sending a
"DIAL-UP INTERRUPT" Queued Protocol message. The line
speed for that DC20 line will then be marked for later
transmission to the TOPS-20 system via the
"Here is Line Speed" Queued Protocol message.
Regardless of whether or not the bit pattern recieved
exactly matches a Control-C or a Carriage-Return, that
character will be discarded, and the interrupt
dismissed. Since the DC20 line is no longer in the
"Auto-Baud Wait" state, all subsequent characters
recieved on that line will be processed as normal input
to TOPS-20.
NOTE
There can exist a relatively large time lag
between the Hardware line speed setting and the
Preliminary Functional Specification for RSX-20F Auto-Baud Detection Page 8
notification of the TOPS-20 system of the new
line speed. This is dependent on the real-time
system state and due to the fact that the
"Here is Line Speed" Queued Protocol message
cannot be initiated from interrupt level, where
the Auto-Baud line speeds are determined and
set. This further implies that a significant
amount of line speed notification overhead may
be incurred, as the entire DH11 section of the
RSX-20F Data Line Scanner must be searched at
task level in order to effect line speed
notification.
If the match is unsucessful, the character recieved
will be discarded and the interrupt for that DC20 line
dismissed without echoing or any futher action taken.
The DC20 Interrupt Service Routine will continue to
reject all input from any particular Auto-Baud DC20
line until such time as it is removed from the
"Auto-Baud Wait" state.
NOTE
The true context of a DC20 line in
"Auto-Baud Wait" is that it is "turned-off".
Therefore, all output directed to a DC20 line
in this state will be ignored.
3.1.3 AUTO-BAUD TERMINATION
When the RSX-20F Front-End disconnects an Auto-Bauded
DC20 line by direction from the TOPS-20