I thought that I had sent a message to the list a few months ago showing the
procedure to use the software DDCMP driver in RSTS V10.1. That's a standard
feature, but undocumented and probably unsupported. It works well and
interoperates with PyDECnet and with the DDCMP implementation in SIMH.
Presumably it will talk to the software DDCMP in RSX, though I have not tried
that.
Attached are the instructions and the program mentioned.
paul
Software DDCMP in RSTS/E V10
NODVR, a software DDCMP driver was written for V9.6 as part of PRO
support (an unreleased and unsanctioned effort). In V10.0 it was made
part of the released product. These notes were reverse engineered
from the V10.1 code, though it is likely they are valid also for
V10.0.
NODVR is an "auxiliary driver", essentially a software coprocessor for
a standard device. In this case, it is associated with a terminal
line, and hooks to the terminal driver to become an alternate
character processor. Any physical terminal port other than the
console can be operated in DDCMP mode, but the PRO display,
pseudo-keyboards, and LAT terminals cannot.
Unlike other DDCMP devices, NODVR does not support use from
application programs. It can only be used as a DECnet data link.
Enabling NODVR support in RSTS.
While the software is built into the OS during SYSGEN, it is not
loaded unless enabled by a flag in the system configuration file
[0,1]CONFIG.SYS. To set this flag:
$ set system/async
The change will take effect after a system reboot. You can use "show
system" to confirm that the software DDCMP driver is loaded.
Starting DDCMP on a terminal line.
Running the DDCMP driver on a given terminal line is a two step
process. The first step enables DDCMP mode by binding an NODVR unit
to the terminal line. The second step starts the DDCMP state machine
for that unit.
1. Set DDCMP mode for a terminal
Before this is done, either the terminal line must be not owned, or it
must be owned (assigned) by the requesting job.
To enable DDCMP mode for a given terminal line, issue this DCL
command:
$ set term kb<x>/proto=ddcmp
Alternatively in a program, open NO0: and issue a .SPEC request with the
following arguments:
XRB: 3 (Function code: set DDCMP mode)
XRBC: Terminal unit number to set to DDCMP mode
On successful completion, the terminal line is now associated with the
DDCMP driver. As part of this, an NO<x>: DDB has been created, where
<x> is the terminal line unit number specified. The terminal line is
now marked as owned by DECnet (owner job appears as "TRN" in the SHOW
DEVICES/ALLOC command).
2. Start DDCMP circuit
Issue a DECnet circuit start request, which is a .MESAG with the
following arguments:
FQFIL = -21 (Function code: circuit control)
FQSIZM = 3 (Subfunction: circuit on)
FQ$MFL = Routing circuit flags [11]
LF.VER ==> Verification required
LF.ANS ==> Answer mode
LF.RST ==> Restartable (512)
LF.TRA ==> Trace for this circuit
FQNAM1 = Originating queue limit [7]
FQNAM1+2 = Recall timer [9]
FQBUFL = Hello timer interval [15]
FQMODE = Operational mode (see below) [17]
FQFLAG = Circuit cost [19]
FQ$CTM = Counter timer [21]
FQDEV,
FQDEVN = Device to use ("TT" in FQDEV, <x> in FQDEVN) [23..26]
FQCLUS = Buffer quota (byte) [27]
Numbers in [ ] indicate character positions in the Basic-PLUS syscall.
FQMODE bit 14 (8192) set indicates a request for sync mode. This is
only valid on a PRO, and then only for the terminal line corresponding
to the communication port. No other mode bits apply to the async DDMP
driver.
Make sure the XRB is zeroed since this is not a data transferring case
of .MESAG. Note that the device name is given as "TT" not "KB" or
"NO"; the DECnet circuit start code recognizes this name as a special
case.
Stopping DDCMP
This involves the reverse of the two steps given above.
1. Stop DDCMP circuit
Issue a DECnet circuit stop request, which is a .MESAG with the
following arguments:
FQFIL = -21 (Function code: circuit control)
FQSIZM = 4 (Subfunction: circuit off)
FQDEV,
FQDEVN = Device to use ("TT" in FQDEV, <x> in FQDEVN)
Make sure the XRB is zeroed since this is not a data transferring case
of .MESAG. Note that the device name is given as "TT" not "KB" or
"NO"; the DECnet circuit start code recognizes this name as a special
case.
2. Disable DDCMP mode for the terminal line
To return the terminal line that was used to normal operation rather
than being bound to the Async DDCMP driver, use the DCL command:
$ set term kb<x>/proto=none
Alternatively in a program, open NO0: and issue a .SPEC request with the
following arguments:
XRB: 4 (Function code: set normal mode)
XRBC: Terminal unit number to revert to normal mode
On successful completion, the terminal line is no longer associated
with the DDCMP driver. Any resources allocated for DDCMP mode have
been freed. Ownership of the terminal line is returned to what it was
before DDCMP mode was set.
