TOPS-20 PANDA and Ethernet woes under PDP10-KL on Raspberry Pi OS Bookworm

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Tony Nicholson

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Feb 16, 2026, 9:45:18 PMFeb 16

to PiDP-10

I thought I'd ask here given the collective knowledge present.

More verbose details below - but in summary, I can't get SIMH PDP10-KL Ethernet networking using DECnet or LAT working from a TOPS-20 PANDA configured system on a Raspberry Pi 3 Model B Plus - running Raspberry Pi OS Bookworm. TCP/IP networking appears to work though.

This is using the pcap interface capability on the NI device to attach to the Pi's eth0 interface. I have also tried bridging a tap interface - with the same results. All my other simulator instances (VAX, PDP-11) running on Raspberry Pis or macOS work with pcap to the Ethernet interface (eth0) - and this is my preferred way of doing this.

I have tried this using the PiDP10 pdp10-kl program (from github.com/obsolescence/pidp10 and re-compiled form source), the Open-SIMH pdp10-kl (from github.com/open-simh/simh built with the Makefile), and Richard Conwell's github.com/rcornwell/sims

Externally on the network the DECnet and LAT multicast packets can be seen by other hosts, but they are not seen by the TOPS-20 system. I can run other Open-SIMH emulators on the Pi (VAX running OpenVMS V7.3 and PDP-11 with RSTS/E and RSX-11/M-Plus) - and their multi-protocol networking using pcap to eth0 all work fine.

A session log running Open SIMH pdp10-kl follows. In it you can see me telnetting to a VAX host that can see the LAT service and DECnet node appear - but any attempt to connect back using LAT, DECnet or CTERM fails. For example, when I try to connect from OpenVMS using LAT it causes a "***BUGINF LATIST***" error under TOPS-20, and CTERM gives node unreachable. It's as though the Ethernet frames are being mangled when passing from eth0 into the NIA20 for these protocols.

Linux pi4 6.12.62+rpt-rpi-v8 #1 SMP PREEMPT Debian 1:6.12.62-1+rpt1~bookworm (2026-01-19) aarch64

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Tue Feb 17 11:12:46 2026 from 192.168.42.28

pi@pi4:~$ echo $TERM #using hardcopy to suppress ANSI escape sequences
la36
pi@pi4:~$ cd simh
pi@pi4:~/simh$ cat panda.ini
; Run TOPS-20 PANDA distribution under Open SIMH
;
; to start use "pdp10-kl panda.ini"
;
; change to disk image directory
cd /home/pi/simh/disk-images/pdp10-kl/tops-20
;
; change SIMH console breakout from CTRL-E to CTRL-\
set console wru=034

;;set console telnet=buffered=144
;;set cons -u telnet=1025

set cpu 4096K kl10b
; idle doesn't work
;set cpu idle
show cpu
;
; tape drive
set tua rh20
set tua1 disable
set tua2 disable
set tua3 disable
set tua4 disable
set tua5 disable
set tua6 disable
set tua7 disable
;
; disk drive
set rpa rh20
set rpa0 rp07
att rpa0 -f dbd9 RH20.RP07.1
set rpa1 disable
set rpa2 disable
set rpa3 disable
set rpa4 disable
set rpa5 disable
set rpa6 disable
set rpa7 disable
set rpb rh20
set rpb disable
show eth
;
; Ethernet
set ni enable
; try using DECnet MAC address for node 35.629
set ni mac=aa:00:04:00:75:8E
;att ni tap:tap0
att ni eth0
show ni
;
; Console
set cty rsx20
;
; Line printer
att lp20 -n prt.lst
;
; User terminals
;att tty -U 2021
att tty -U 10018
;
echo
echo =============================
;;echo Console is on telnet 1025
echo Terminal 1 is on telnet 10018
echo =============================
echo
dep sw 254200000147
load boot.sav
echo For normal TOPS-20 startup enter TOPS20: to the BOOT> prompt
echo and system structure TOPS20.
echo For changing the configuration, enter TOPS20:/e to the BOOT> prompt,
echo followed by dbugsw/2 and then 147<ESC>g
echo
continue
show eth

pi@pi4:~/simh$ ~/src/simh/BIN/pdp10-kl panda.ini

KL-10 simulator Open SIMH V4.1-0 Current git commit id: 4d383732
CPU idle disabled, Serial: 1025 (default)
4MW, KL10B, DF10C
ETH devices:
eth0 eth0 (No description available)
eth1 wlan0 (No description available)
eth2 tap:tapN (Integrated Tun/Tap support)
eth3 vde:device{:switch-port-number} (Integrated VDE support)
eth4 nat:{optional-nat-parameters} (Integrated NAT (SLiRP) support)
eth5 udp:sourceport:remotehost:remoteport (Integrated UDP bridge support)
/home/pi/simh/panda.ini-49> att ni eth0
%SIM-INFO: Eth: opened OS device eth0
NI MAC=AA:00:04:00:75:8E
attached to eth0
/home/pi/simh/panda.ini-56> att lp20 -n prt.lst
%SIM-INFO: LP20: creating new file: prt.lst
/home/pi/simh/panda.ini-60> att tty -U 10018
%SIM-INFO: Listening on port 10018

=============================
Terminal 1 is on telnet 10018
=============================

Start addr=040000
For normal TOPS-20 startup enter TOPS20: to the BOOT> prompt
and system structure TOPS20.
For changing the configuration, enter TOPS20:/e to the BOOT> prompt,
followed by dbugsw/2 and then 147<ESC>g

BOOT V11.0(315)

BOOT>TOPS20:

[BOOT: Loading] [OK]

System structure not found. What is its name? TOPS20

[TOPS20 mounted]
SIMH PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4 Internet: Loading host names [OK]

System res
Date and time is: Tuesday, 17-February-2026 11:15AM
Why reload? other
Run CHECKD? y
[Checking file consistency]
Checking system
[Working on structure TOPS20:]

% Rebuilding symbol table for TOPS20:<ACCOUNTS> [OK]

Local count of file pages: 105409
Local count of overhead Check of system stru pages: 28787
Local count of used pages: 134196

System count before CHECKD: 134230
System count after CHECKD: 134230

There are 34 lost pages

Addresses are in file TOPS20:<OPERATOR>TOPS20-LOST-PAGES.BIN.22
DDMP: Started
[KNILDR: Loading microcode version 1(172) into Ethernet channel 0]

SYSJOB 7A(88)-4 started at 17-Feb-2026 1117
SJ 0: @LOGIN OPERATOR
SJ 0: @ENABLE
SJ 0: $SYSTEM:STSJ1
17-Feb-2026 11:17:36 SYSJB1: SYSJB1 started.
SJ 0: $^ESET LOGIN ANY
SJ 0: $OPR
17-Feb-2026 11:17:34 Internet: Network LOCALNET on, Output on
17-Feb-2026 11:17:43 SYSJB1: Job 0:
17-Feb-2026 11:17:43 SYSJB1: Job 0: SIMH PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:17:43 SYSJB1: Job 1:
17-Feb-2026 11:17:43 SYSJB1: Job 1: SIMH PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:17:44 SYSJB1: Job 2:
17-Feb-2026 11:17:44 SYSJB1: Job 2: SIMH PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:17:44 SYSJB1: Job 3:
17-Feb-2026 11:17:44 SYSJB1: Job 3: SIMH PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:17:45 SYSJB1: Job 4:
17-Feb-2026 11:17:45 SYSJB1: Job 4: SIMH PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:17:45 SYSJB1: Job 5:
17-Feb-2026 11:17:45 SYSJB1: Job 5: SIMH PDP10-KL, PANDA TOPS-20 Monitor 7.1(2173
% [Logger 17-Feb-2026 11:17:46 ]: Started at 17-Feb-2026 11:17:43
3)-4
17-Feb-2026 11:17:46 SYSJB1: Job 6:
17-Feb-2026 11:17:46 SYSJB1: Job 6: SIMH PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:17:46 SYSJB1: Job 7:
17-Feb-2026
SJ 0: OPR>TAKE SYSTEM:SYSTEM.CMD
11:17:46 SYSJB1: Job 7: SIMH PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:17:47 SYSJB1: Job 1: @LOGIN OPERATOR
17-Feb-2026 11:17:47 SYSJB1: Job 3: @LOGIN OPERATOR
17-Feb-2026 11:17:47 SYSJB1: Job 5: @LOGIN OPERATOR
17-Feb-2026 11:17:48 SYSJB1: Job 5: @ENABLE
17-Feb-2026 11:17:48 SYSJB1: Job 7: @LOGIN OPERATOR
17-Feb-2026 11:17:48 SYSJB1: Job 0: @LOGIN OPERATOR
17-Feb-2026 11:17:48 SYSJB1: Job 1: @ENABLE
17-Feb-2026 11:17:48 SYSJB1: Job 2: @LOGIN OPERATOR
17-Feb-2026 11:17:48 SYSJB1: Job 2: @ENABLE
17-Feb-2026 11:17:48 SYSJB1: Job 3: @ENABLE
17-Feb-2026 11:17:48 SYSJB1: Job 4: @LOGIN OPERATOR
17-Feb-2026 11:17:48 SYSJB1: Job 5: $FTS
17-Feb-2026 11:17:48 SYSJB1: Job 6: @LOGIN OPERATOR
17-Feb-2026 11:17:49 SYSJB1: Job 6: @ENABLE
17-Feb-2026 11:17:49 SYSJB1: Job 7: @ENABLE
17-Feb-2026 11:17:49 SYSJB1: Job 0: @ENABLE
17-Feb-2026 11:17:49 SYSJB1: Job 1: $NETSRV
17-Feb-2026 11:17:49 SYSJB1: Job 2: $SMTJFN
17-Feb-2026 11:17:49 SYSJB1: Job 3: $MMAILR
17-Feb-2026 11:17:50 SYSJB1: Job 4: @ENABLE
17-Feb-2026 11:17:50 SYSJB1: Job 6: $MX
17-Feb-2026 11:17:50 SYSJB1: Job 7: $RUN SYS:SETNOD
17-Feb-2026 11:17:50 SYSJB1: Job 0: $RESOLV
17-Feb-2026 11:17:52 SYSJB1: Job 4: $IMAPSV
17-Feb-2026 11:17:52 SYSJB1: Job 7: SETNOD>GET SYSTEM:DECNET-NODES.DAT
17-Feb-2026 11:17:53 SYSJB1: Job 7: SETNOD>INSERT
17-Feb-2026 11:17:53 SYSJB1: Job 7: SETNOD>EXIT
17-Feb-2026 11:17:53 SYSJB1: Job 7: $LOGOUT
SJ 0:
SJ 0: 11:17:53 --ORION logging disabled by job 1 OPERATOR at terminal 13--
17-Feb-2026 11:17:54 SYSJB1: Job 5: FTS>TAKE FTS.CMD
17-Feb-2026 11:17:54 SYSJB1: Job 7: [Jobs 0(DET), 1, 2(DET), 3, 4, 5, 6, 7, 8, 9 also logged in under O
SJ 0:
SJ 0: 11:17:54 --Output display for OPR modified--
SJ 0:
SJ 0: 11:17:54 --Output display for OPR modified--
SJ 0:
SJ 0: 11:17:54 --Output display for OPR modified--
SJ 0:
SJ 0: 11:17:55 --Output display for OPR modified--
PERATOR]
17-Feb-2026 11:17:55 SYSJB1: Job 7: Killed Job 10, User OPERATOR, TTY23, at 17-Feb-2026 11:17:55
17-Feb-2026 11:17:55 SYSJB1: Job 7: Used 0:00:00 in 0:00:07
SJ 0:
SJ 0: 11:17:50 Batch-Stream 0 -- Set Accepted --
SJ 0:
SJ 0: 11:17:50 Batch-Stre
17-Feb-2026 11:17:55 SYSJB1:am 1 -- Set Accepted --
SJ 0:
SJ 0: 11:17:50 Batch-Stream 2 -- Set Accepted --
Job 5: [FTS20: FTS event 38: spooler started]
SJ 0:
SJ 0: 11:17:50 Batch-Stream 3 -- Set Accepted --
SJ 0:
SJ 0: 11:17:50 Batch-Stream 0 -- Set Accepted --
SJ 0:
SJ 0: 11:17:50 Batch-Stream 1 -- Set Accepted --
SJ 0:
SJ 0: 11:17:50 Batch-Stream 2 -- Set Accepted --
SJ 0:
SJ 0: 11:17:50 Batch-Stream 3 -- Set Accepted --
SJ 0:
SJ 0: 11:17:50 Batch-Stream 0 -- Startup Scheduled --
SJ 0:
SJ 0: 11:17:50 Batch-Stream 1 -- Startup Scheduled --
SJ 0:
SJ 0: 11:17:50 Batch-Stream 2 -- Startup Scheduled --
SJ 0:
SJ 0: 11:17:50 Batch-Stream 3 -- Startup Scheduled --
SJ 0:
SJ 0: 11:17:52 -- Structure Status Change Detected --
SJ 0: Previously mounted structure TOPS20: detected
SJ 0:
SJ 0: 11:17:52 -- Structure Status Change Detected --
SJ 0: Structure state for structure TOPS20 is incorrect
SJ 0: EXCLUSIVE/SHARED attribute set incorrectly
SJ 0: Status of structure TOPS20: is set:
SJ 0: Domestic, Unregulated, Shared, Available, Dumpable
SJ 0:
SJ 0:
SJ 0: 11:17:57 [LCP] -- Set Accepted --

SJ 0:
SJ 0:
SJ 0: 11:17:57 [LCP] -- Set Accepted --

SJ 0:
SJ 0:
SJ 0: 11:17:57 [LCP] -- Set Accepted --

SJ 0:
SJ 0:
SJ 0: 11:17:57 [LCP] -- Set Accepted --

SJ 0:
SJ 0:
SJ 0: 11:17:57 [LCP] -- Set Accepted --

SJ 0:
SJ 0:
SJ 0: 11:17:57 [LCP] -- Start Accepted --

SJ 0:
SJ 0:
SJ 0: 11:18:02 [LCP] -- Host Characteristics --

SJ 0:
SJ 0: LAT Access State: ON
SJ 0: Host Name: PANDA
SJ 0: Host id: "SIMH PDP10-KL (PANDA)"
SJ 0: Host number: 629
SJ 0: Retransmit Limit: 60
SJ 0: Retransmit Timer: 1000
SJ 0: Multicast Timer: 30
SJ 0: Groups: 0:255

SJ 0:
SJ 0: Current Maximum
SJ 0
11:18:08 From operator terminal 13 on node : ------- -------
SJ 0: Allocated circuits 0 52
SJ 0: Active circuits 0 20
SJ 0: Sessions 0 5
SJ 0:
SJ 0: Service Name Rating Identification
SJ 0: -------------------- ------ ------------------------
SJ 0: PANDA D TOPS-20 V7.1
SJ 0:
SJ 0: 11:18:09 --SEND command completed--
SJ 0:
SJ 0: 11:18:08 NCP
SJ 0:
SJ 0: Request # 1; Set Logging Completed
SJ 0:
SJ 0: 11:18:08 NCP
SJ 0:
SJ 0: Request # 2; Set Logging Completed
SJ 0:
SJ 0: 11:18:08 NCP
SJ 0:
SJ 0: Request # 3; Set Circuit Completed
SJ 0:
SJ 0: 11:18:08 NCP
SJ 0:
SJ 0: Request # 4; Set Circuit Completed
SJ 0:
SJ 0: 11:18:08 NCP
SJ 0:
SJ 0: Request # 5; Set Circuit Completed

SIMH PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4

This system is for the use of authorized users only. Usage of
this system may be monitored and recorded by system personnel.

Anyone using this system expressly consents to such monitoring
and is advised that if such monitoring reveals possible
evidence of criminal activity, system personnel may provide the
evidence from such monitoring to law enforcement officials.

@^C
@operator
Password:
@enable
$term la36
$info internet
Network LOCALNET host name is panda.localdomain
Network interface type is IPNI, Internet address is 192.168.42.29
Network interface is up, output is enabled
Network service is enabled
Last network interface up transition: 17-Feb-2026 11:17:34
$opr
OPR>ncp show known circ char
OPR>
11:20:32 NCP

Request # 6; Show Known Circuits Characteristics Completed

Circuit = NI-0-0

Service = Enabled
Cost = 4
Maximum Routers = 16
Router Priority = 5
Hello Timer = 15
Type = Ethernet
OPR>lcp show counters
OPR>
11:22:30 [LCP] -- Counter Totals for All Servers --

Messages received: 0
Messages transmitted: 0
Messages retransmitted: 0
Sequence errors received: 0
Illegal messages received: 0
Illegal slots received: 0
Resource failures: 0
OPR>exit
$
$! telnet to VAX
$telnet vogon
Trying... Open

OpenVMS(TM) VAX V7.3 *** AUTHORISED USE ONLY ***

Username: system/nocomm

Password:

Hobbyist node VOGON. Authorised use only.

Last interactive login on Tuesday, 17-FEB-2026 11:02
Last non-interactive login on Tuesday, 17-FEB-2026 01:00

$
$ set term/la36

$ show net/old

OpenVMS Network status for local node 35.606 VOGON on FEBRUARY 17, 2026 11:25 AM

The next hop to the nearest area router is node 35.699 TNRTR.

Node Links Cost Hops Next Hop to Node

35.600 FAUNA 0 4 1 QNA-0 -> 35.630 KOALA
35.619 DINGO 0 4 1 QNA-0 -> 35.619 DINGO
35.629 PANDA 0 4 1 QNA-0 -> 35.629 PANDA
35.630 KOALA 0 4 1 QNA-0 -> 35.630 KOALA
35.636 RUSTY 0 4 1 QNA-0 -> 35.636 RUSTY
35.654 GALAH 0 4 1 QNA-0 -> 35.654 GALAH
35.687 DUGONG 0 4 1 QNA-0 -> 35.687 DUGONG
35.692 BROLGA 0 4 1 QNA-0 -> 35.692 BROLGA
35.699 TNRTR 0 4 1 QNA-0 -> 35.699 TNRTR
35.701 GUARD 0 17 4 QNA-0 -> 35.699 TNRTR
35.799 MBRTR 0 13 3 QNA-0 -> 35.699 TNRTR
35.1023 A35RTR 0 9 2 QNA-0 -> 35.699 TNRTR

Total of 12 nodes.

$ mcr latcp
LATCP> show service panda

Service Name: PANDA
Service Status: Available
Service Ident: TOPS-20 V7.1

Node Name Status Rating Identification
PANDA Reachable 254 TOPS-20 V7.1

LATCP> *EXIT*

$ set host /lat panda
17-Feb-2026 11:30:22 ***BUGINF LATIST*** LAT Illegal Slot Received, Data: 6512725, 0, 524000040000, 275070000000
SJ 0: OPR>
SJ 0: 11:30:22 -- Message from timesharing user --
SJ 0: job 0 OPERATOR detached
SJ 0: 17-Feb-2026 11:30:22 ***BUGINF LATIST*** LAT Illegal Slot Received, Data: 6512725, 0, 524000040000, 275070000000
SJ 0:

%LAT-F-PROTERR, communication protocol error
-LAT-I-END, control returned to node VOGON

$ set host panda

%SYSTEM-F-UNREACHABLE, remote node is not currently reachable

$ logout

SYSTEM logged out at 17-FEB-2026 11:32:22.32

Connection closed by foreign host
$opr
OPR>lcp show counter

11:33:06 [LCP] -- Counter Totals for All Servers --

Messages received: 2
Messages transmitted: 2
Messages retransmitted: 0
Sequence errors received: 0
Illegal messages received: 0
Illegal slots received: 1
Resource failures: 0
OPR>ncp show adjac
OPR>
11:34:50 NCP

Request # 7; Show Adjacent Nodes Summary Completed

No Information

OPR>ncp show known circ char
OPR>
11:35:30 NCP

Request # 8; Show Known Circuits Characteristics Completed

Circuit = NI-0-0

Service = Enabled
Cost = 4
Maximum Routers = 16
Router Priority = 5
Hello Timer = 15
Type = Ethernet
OPR>exit
$
$! break out to simh to do a show eth
$
Simulation stopped, PC: 142474 (POPJ 17,0)
ETH devices:
eth0 eth0 (No description available)
eth1 wlan0 (No description available)
eth2 tap:tapN (Integrated Tun/Tap support)
eth3 vde:device{:switch-port-number} (Integrated VDE support)
eth4 nat:{optional-nat-parameters} (Integrated NAT (SLiRP) support)
eth5 udp:sourceport:remotehost:remoteport (Integrated UDP bridge support)
Open ETH Devices:
NI eth0 (No description available)
Ethernet Device:
Name: eth0
Reflections: 0
Self Loopbacks Sent: 2
Self Loopbacks Rcvd: 0
Host NIC Address: B8:27:EB:62:28:4B
Jumbo Dropped: 4
Jumbo Fragmented: 1
Packets Sent: 1172
Packets Received: 1965
Asynch Interrupts: Enabled
Interrupt Latency: 0 uSec
Read Queue: Count: 4
Read Queue: High: 200
Read Queue: Loss: 67
Peak Write Queue Size: 1
MAC Filter[ 0]: AA:00:04:00:75:8E
MAC Filter[ 1]: FF:FF:FF:FF:FF:FF
MAC Filter[ 2]: FF:FF:FF:FF:FF:FF
MAC Filter[ 3]: CF:00:00:00:00:00
MAC Filter[ 4]: AB:00:00:02:00:00
BPF Filter: (((ether dst AA:00:04:00:75:8E) or (ether dst FF:FF:FF:FF:FF:FF) or (ether dst CF:00:00:00:00:00) or (ether dst AB:00:00:02:00:00)))
sim> cont

$^Ecease now
PANDA Will be shut down IMMEDIATELY
[Confirm]

[Timeshari17-Feb-2026 11:37:07 ACJ: System shutdown set by job 10, user OPERATOR, program CEASE, TTY5

OPERATOR - Wait for the message "Shutdown complete" before
entering commands to PARSER.
$
SJ 0: OPR>Killed Job 1, User OPERATOR, TTY13, at 17-Feb-2026 11:37:09
SJ 0: Used 0:00:01 in 0:19:34
17-Feb-2026 11:37:14 HSYS: Shutdown complete

Simulation stopped, PC: 142460 (SKIPE 0,316433)
sim> exit
Goodbye
%SIM-INFO: Eth: closed eth0
pi@pi4:~/simh$

pi@pi4:~/simh$ exit

I can run my configured Panda disk image using both the original KLH10 2.0H linux binaries supplied in Mark Crispin's original panda-dist.tar.gz distribution under x86_64 Ubuntu Desktop 24.04.4 LTS, and a KLH10 2.0l binary I built from github.com/PDP-10/klh10 (also under x86_64 Ubuntu Desktop 24.04.4 LTS). Both are running as root with the dpni20 program set as suid root.

Both of these KLH10 versions seem to work for TCP/IP networking, DECnet and LAT - although I notice that running KLH10 forces a change to the Ethernet MAC address to use the DECnet-style MAC address that remains after KLH10 is shutdown. The older version is using a shared Ethernet, while to newer is using pcap.

[As an aside - I previously ran KLH10 under Solaris 10 on an Ultra-SPARC SunBlade-100 using a shared Ethernet configuation and there were similar issues getting DECnet to work on it - that I won't go into here].

Here's a transcript of a session under KLH10 2.0l on x86_64 showing fully functioning networking -

KLH10 2.0l (MyKL) built Feb 16 2026 09:50:14
Copyright � 2002 Kenneth L. Harrenstien -- All Rights Reserved.
This program comes "AS IS" with ABSOLUTELY NO WARRANTY.

Compiled for unknown-linux-gnu on x86_64 with word model USEINT
Emulated config:
CPU: KL10-extend SYS: T20 Pager: KL APRID: 3600
Memory: 8192 pages of 512 words (SHARED)
Time interval: INTRP Base: OSGET
Interval default: 60Hz
Internal clock: OSINT
Other: MCA25 CIRC JPC DEBUG PCCACHE CTYINT EVHINT
Devices: DTE RH20 RPXX(DP) TM03(DP) NI20(DP)
[MEM: Allocating 8192 pages shared memory, clearing...done]

KLH10# ; Define basic device config - one DTE, one disk, one tape
KLH10# devdef dte0 200 dte master
KLH10# devdef rh0 540 rh20
KLH10# devdef rh1 544 rh20
KLH10# devdef dsk0 rh0.0 rp type=rp07 format=dbd9
KLH10# devdef mta0 rh1.0 tm03 type=tu45
KLH10#
KLH10# ; Set Ethernet address
KLH10# ;(old version for use with panda-dist KLH10 2.0H linux binaries
KLH10# ;but has the side-effect of changing the MAC address of the linux
KLH10# ;host's MAC address to the DECnet address))
KLH10# ;devdef ni0 564 ni20 ifc=enp0s3 ipaddr=192.168.42.29 decnet=true
KLH10# ;
KLH10# ;(updated version of KLH10 2.0l from GitHub uses pcap)
KLH10# devdef ni0 564 ni20 ifc=enp0s3 ifmeth=pcap dedic=true decnet=true
KLH10#
KLH10# ; Define the idle device on 700
KLH10# devdef idler 700 host
KLH10#
KLH10# ; Set switch register
KLH10# set sw=254200,,147
sw: 0,,0 => 254200,,147
KLH10#
KLH10# ; Set console lights I/O base register
KLH10# ;Uncomment the following line if you have a Panda display.
KLH10# ;lights 378
KLH10#
KLH10# ; Load disk bootstrap directly
KLH10# load boot.sav
Using word format "c36"...
Loaded "boot.sav":
Format: DEC-CSAV
Data: 4630, Symwds: 0, Low: 040000, High: 054641, Startaddress: 040000
Entvec: JRST (120 ST: 0, 124 RE: 0, 137 VR: 0,,0)
KLH10#
KLH10# ; Ready to GO
KLH10# [EOF on klt20.ini]
KLH10# Starting KN10 at loc 040000...

BOOT V11.0(315)

BOOT>

[BOOT: Loading] [OK]

[TOPS20 mounted]
KLH10 PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4 Internet: Loading host names [OK]

System restarting, wait...
Date and time is: Tuesday, 17-February-2026 11:39AM
Why reload? other
Run CHECKD? y
[Checking file consistency]
Checking system structure.

[Working on structure TOPS20:]

% Rebuilding symbol table for TOPS20:<ACCOUNTS> [OK]

Local count of file pages: 106298
Local count of overhead pages: 28811
Local count of used pages: 135109

System count before CHECKD: 135109
System count after CHECKD: 135109

There are no lost pages.
Check of system structure completed.
DDMP: Started
[KNILDR: Loading microcode version 1(172) into Ethernet channel 0]

[dpni20: ifc "enp0s3" => ether aa:0:4:0:75:8e]
[dpni20: VHOST 0.0.0.0]

SYSJOB 7A(88)-4 started at 17-Feb-2026 1140
SJ 0: @LOGIN OPERATOR
SJ 0: @ENABLE
SJ 0: $SYSTEM:STSJ1
17-Feb-2026 11:40:06 SYSJB1: SYSJB1 started.
SJ 0: $^ESET LOGIN ANY
SJ 0: $OPR
17-Feb-2026 11:40:06 SYSJB1: Job 0:
17-Feb-2026 11:40:06 SYSJB1: Job 0: KLH10 PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:40:06 SYSJB1: Job 1:
17-Feb-2026 11:40:06 SYSJB1: Job 1: KLH10 PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:40:06 SYSJB1: Job 2:
17-Feb-2026 11:40:06 SYSJB1: Job 2: KLH10 PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:40:06 SYSJB1: Job 3:
17-Feb-2026 11:40:06 SYSJB1: Job 3: KLH10 PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:40:06 SYSJB1: Job 4:
17-Feb-2026 11:40:06 SYSJB1: Job 4: KLH10 PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:40:06 SYSJB1: Job 5:
17-Feb-2026 11:40:06 SYSJB1: Job 5: KLH10 PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:40:06 SYSJB1: Job 6:
17-Feb-2026 11:40:06 SYSJB1: Job 6: KLH10 PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:40:06 SYSJB1: Job 7:
17-Feb-2026 11:40:06 SYSJB1: Job 7: KLH10 PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4
17-Feb-2026 11:40:06 SYSJB1: Job 1: @LOGIN OPERATOR
17-Feb-2026 11:40:06 SYSJB1: Job 3: @LOGIN OPERATOR
17-Feb-2026 11:40:06 SYSJB1: Job 5: @LOGIN OPERATOR
17-Feb-2026 11:40:06 SYSJB1: Job 0: @LOGIN OPERATOR
17-Feb-2026 11:40:06 SYSJB1: Job 2: @LOGIN OPERATOR
17-Feb-2026 11:40:06 SYSJB1: Job 2: @ENABLE
17-Feb-2026 11:40:06 SYSJB1: Job 3: @ENABLE
17-Feb-2026 11:40:06 SYSJB1: Job 4: @LOGIN OPERATOR
17-Feb-2026 11:40:06 SYSJB1: Job 5: @ENABLE
17-Feb-2026 11:40:06 SYSJB1: Job 6: @LOGIN OPERATOR
17-Feb-2026 11:40:06 SYSJB1: Job 6: @ENABLE
17-Feb-2026 11:40:06 SYSJB1: Job 7: @LOGIN OPERATOR
17-Feb-2026 11:40:06 SYSJB1: Job 0: @ENABLE
17-Feb-2026 11:40:06 SYSJB1: Job 1: @ENABLE
17-Feb-2026 11:40:06 SYSJB1: Job 2: $SMTJFN
17-Feb-2026 11:40:06 SYSJB1: Job 3: $MMAILR
17-Feb-2026 11:40:06 SYSJB1: Job 4: @ENABLE
17-Feb-2026 11:40:06 SYSJB1: Job 5: $FTS
17-Feb-2026 11:40:06 SYSJB1: Job 6: $MX
17-Feb-2026 11:40:06 SYSJB1: Job 7: @ENABLE
17-Feb-2026 11:40:06 SYSJB1: Job 0: $RESOLV
17-Feb-2026 11:40:06 SYSJB1: Job 1: $NETSRV
17-Feb-2026 11:40:06 SYSJB1: Job 4: $IMAPSV
17-Feb-2026 11:40:06 SYSJB1: Job 7: $RUN SYS:SETNOD
17-Feb-2026 11:40:07 SYSJB1: Job 5: FTS>TAKE FTS.CMD
17-Feb-2026 11:40:07 SYSJB1: Job 7: SETNOD>GET SYSTEM:DECNET-NODES.DAT
17-Feb-2026 11:40:07 SYSJB1: Job 7: SETNOD>INSERT
17-Feb-2026 11:40:07 SYSJB1: Job 7: SETNOD>EXIT
17-Feb-2026 11:40:07 SYSJB1: Job 7: $LOGOUT
17-Feb-2026 11:40:07 SYSJB1: Job 7: [Jobs 0(DET), 1, 2(DET), 3, 4, 5, 6, 7, 8, 9 also logged in under OPERATOR]
17-Feb-2026 11:40:07 SYSJB1: Job 5: [FTS20: FTS event 38: spooler started]
17-Feb-2026 11:40:07 SYSJB1: Job 7: Killed Job 10, User OPERATOR, TTY23, at 17-Feb-2026 11:40:07
17-Feb-2026 11:40:07 SYSJB1: Job 7: Used 0:00:00 in 0:00:00

% [Logger 17-Feb-2026 11:40:09 ]: Started at 17-Feb-2026 11:40:06
SJ 0: OPR>TAKE SYSTEM:SYSTEM.CMD
SJ 0:
SJ 0: 11:40:09 --ORION logging disabled by job 1 OPERATOR at terminal 13--
SJ 0:
SJ 0: 11:40:09 --Output display for OPR modified--
SJ 0:
SJ 0: 11:40:09 --Output display for OPR modified--
SJ 0:
SJ 0: 11:40:09 --Output display for OPR modified--
SJ 0:
SJ 0: 11:40:09 --Output display for OPR modified--
SJ 0:
SJ 0: 11:40:09 Batch-Stream 0 -- Set Accepted --
SJ 0:
SJ 0: 11:40:09 Batch-Stream 1 -- Set Accepted --
SJ 0:
SJ 0: 11:40:09 Batch-Stream 2 -- Set Accepted --
SJ 0:
SJ 0: 11:40:09 Batch-Stream 3 -- Set Accepted --
SJ 0:
SJ 0: 11:40:09 Batch-Stream 0 -- Set Accepted --
SJ 0:
SJ 0: 11:40:09 Batch-Stream 1 -- Set Accepted --
SJ 0:
SJ 0: 11:40:09 Batch-Stream 2 -- Set Accepted --
SJ 0:
SJ 0: 11:40:09 Batch-Stream 3 -- Set Accepted --
SJ 0:
SJ 0: 11:40:09 Batch-Stream 0 -- Startup Scheduled --
SJ 0:
SJ 0: 11:40:09 Batch-Stream 1 -- Startup Scheduled --
SJ 0:
SJ 0: 11:40:09 Batch-Stream 2 -- Startup Scheduled --
SJ 0:
SJ 0: 11:40:09 Batch-Stream 3 -- Startup Scheduled --
17-Feb-2026 11:40:06 Internet: Network LOCALNET on, Output on
SJ 0:
SJ 0: 11:40:14 [LCP] -- Set Accepted --

SJ 0:
SJ 0:
SJ 0: 11:40:14 [LCP] -- Set Accepted --

SJ 0:
SJ 0:
SJ 0: 11:40:14 [LCP] -- Set Accepted --

SJ 0:
SJ 0:
SJ 0: 11:40:14 [LCP] -- Set Accepted --

SJ 0:
SJ 0:
SJ 0: 11:40:14 [LCP] -- Set Accepted --

SJ 0:
SJ 0:
SJ 0: 11:40:14 [LCP] -- Start Accepted --

SJ 0:
SJ 0:
SJ 0: 11:40:14 -- Structure Status Change Detected --
SJ 0: Previously mounted structure TOPS20: detected
SJ 0:
SJ 0: 11:40:14 -- Structure Status Change Detected --
SJ 0: Structure state for structure TOPS20 is incorrect
SJ 0: EXCLUSIVE/SHARED attribute set incorrectly
SJ 0: Status of structure TOPS20: is set:
SJ 0: Domestic, Unregulated, Shared, Available, Dumpable
SJ 0:
SJ 0:
SJ 0: 11:40:19 [LCP] -- Host Characteristics --

SJ 0:
SJ 0: LAT Access State: ON
SJ 0: Host Name: PANDA
SJ 0: Host id: "KLH10 PDP10-KL (PANDA)"
SJ 0: Host number: 629
SJ 0: Retransmit Limit: 60
SJ 0: Retransmit Timer: 1000
SJ 0: Multicast Timer: 30
SJ 0: Groups: 0:255

SJ 0:
SJ 0: Current Maximum
SJ 0: ------- -------
SJ 0: Allocated circuits 0 52
SJ 0: Active circuits 0 20
SJ 0: Sessions 0 5
SJ 0:
SJ 0: Service Name Rating Identification
SJ 0: -------------------- ------ ------------------------
SJ 0: PANDA D TOPS-20 V7.1

11:40:24 From operator terminal 13 on node PANDA::
=>PANDA System in operation
SJ 0:
SJ 0: 11:40:24 --SEND command completed--
SJ 0:
SJ 0: 11:40:24 NCP
SJ 0:
SJ 0: Request # 1; Set Logging Completed
SJ 0:
SJ 0: 11:40:24 NCP
SJ 0:
SJ 0: Request # 2; Set Logging Completed
SJ 0:
SJ 0: 11:40:24 NCP
SJ 0:
SJ 0: Request # 3; Set Circuit Completed
SJ 0:
SJ 0: 11:40:24 NCP
SJ 0:
SJ 0: Request # 4; Set Circuit Completed
SJ 0:
SJ 0: 11:40:24 NCP
SJ 0:
SJ 0: Request # 5; Set Circuit Completed

KLH10 PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4

This system is for the use of authorized users only. Usage of
this system may be monitored and recorded by system personnel.

Anyone using this system expressly consents to such monitoring
and is advised that if such monitoring reveals possible
evidence of criminal activity, system personnel may provide the
evidence from such monitoring to law enforcement officials.

@operator
Password:
@enable
$term la36
$info internet
Network LOCALNET host name is panda.localdomain
Network interface type is IPNI, Internet address is 192.168.42.29
Network interface is up, output is enabled
Network service is enabled
Last network interface up transition: 17-Feb-2026 11:40:06

$
$telnet vogon
SJ 0: OPR>
SJ 0: 11:43:31 -- DECnet link message --
SJ 0:
SJ 0: Communication failure to the following nodes:
SJ 0: 28NH
SJ 0:
Trying... Open

OpenVMS(TM) VAX V7.3 *** AUTHORISED USE ONLY ***

Username: system/nocomm

Password:

Hobbyist node VOGON. Authorised use only.

Last interactive login on Tuesday, 17-FEB-2026 11:24
Last non-interactive login on Tuesday, 17-FEB-2026 01:00

$ set term /la36

$ mcr latcp
LATCP> show service panda

Service Name: PANDA
Service Status: Available
Service Ident: TOPS-20 V7.1

Node Name Status Rating Identification
PANDA Reachable 255 TOPS-20 V7.1

LATCP> *EXIT*

$ set host /lat panda

%LAT-S-CONNECTED, session to PANDA established
%LAT-I-TODISCON, type ^\ to disconnect the session

KLH10 PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4

This system is for the use of authorized users only. Usage of
this system may be monitored and recorded by system personnel.

Anyone using this system expressly consents to such monitoring
and is advised that if such monitoring reveals possible
evidence of criminal activity, system personnel may provide the
evidence from such monitoring to law enforcement officials.

@tony
Password:
Job 11 on TTY121 VOGON:UIC_000001000004(LAT) 17-Feb-2026 11:44:32
Last interactive login 16-Feb-2026 20:05:56
Last non-interactive login Never
End of LOGIN.CMD.1
@sys
Tue 17-Feb-2026 11:44:45 Up 0:05:04
1+10 Jobs Load av 0.07 0.05 0.03

No operator in attendance

System is remedial

Job Line Program User Origin
11* 121 SYSTAT TONY VOGON:UIC_000001000004(LAT)

1 13 OPR OPERATOR
2 DET SYSJB1 OPERATOR
3 14 RESOLV OPERATOR
4 15 NETSRV OPERATOR
5 16 SMTJFN OPERATOR
6 17 MMAILR OPERATOR
7 20 IMAPSV OPERATOR
8 21 FTS OPERATOR
9 22 MX OPERATOR
10 5 TELNET OPERATOR
@logout
[H [JKilled Job 11, User TONY, TTY121 VOGON:UIC_000001000004, at 17-Feb-2026 11:44:50
Used 0:00:00 in 0:00:17
K
%LAT-I-DISCONNECTED, session disconnected from PANDA

-LAT-I-END, control returned to node VOGON

$ set host panda

KLH10 PDP10-KL, PANDA TOPS-20 Monitor 7.1(21733)-4

This system is for the use of authorized users only. Usage of
this system may be monitored and recorded by system personnel.

Anyone using this system expressly consents to such monitoring
and is advised that if such monitoring reveals possible
evidence of criminal activity, system personnel may provide the
evidence from such monitoring to law enforcement officials.

@tony
Password:
Job 11 on TTY114 VOGON::SYSTEM(CTM) 17-Feb-2026 11:45:03
Last interactive login 17-Feb-2026 11:44:32
Last non-interactive login Never
End of LOGIN.CMD.1
@sys
Tue 17-Feb-2026 11:45:05 Up 0:05:25
1+10 Jobs Load av 0.07 0.05 0.03

No operator in attendance

System is remedial

Job Line Program User Origin
11* 114 SYSTAT TONY VOGON::SYSTEM(CTM)

1 13 OPR OPERATOR
2 DET SYSJB1 OPERATOR
3 14 RESOLV OPERATOR
4 15 NETSRV OPERATOR
5 16 SMTJFN OPERATOR
6 17 MMAILR OPERATOR
7 20 IMAPSV OPERATOR
8 21 FTS OPERATOR
9 22 MX OPERATOR
10 5 TELNET OPERATOR
@nft
NFT>dir vogon::
Access information for node VOGON::
User:
Account:
Password:

VOGON::SYS$SPECIFIC:[DECNET]
DCPS027.DIR;1;P565656 3 4608(8) 19-Jan-2026 09:58:08
NETSERVER.LOG;1;P775606 3 4608(8) 17-Feb-2026 11:45:30
PASCAL060.DIR;1;P565656 3 4608(8) 19-Jan-2026 08:56:03
NFT>exit
@host vogon

[Attempting a connection, connect OK]
[Remote host is a VMS system]
[TYPE ^P to return to node PANDA]

OpenVMS(TM) VAX V7.3 *** AUTHORISED USE ONLY ***

Username: tony/nocomm

Password:

Hobbyist node VOGON. Authorised use only.

Last interactive login on Tuesday, 17-FEB-2026 10:51
Last non-interactive login on Tuesday, 17-FEB-2026 11:00

$ show users
OpenVMS User Processes at FEBRUARY 17, 2026 11:46 AM
Total number of users = 2, number of processes = 3

Username Interactive Subprocess Batch
SYSTEM 2
TONY 1

$ show users /fu
OpenVMS User Processes at FEBRUARY 17, 2026 11:46 AM
Total number of users = 2, number of processes = 3

Username Process Name PID Terminal
SYSTEM SYSTEM 00000183 VTA26: NTY13: (panda.localdomain/33411)
SYSTEM Tony Nicholson 0000005E OPA0:
TONY TONY 00000187 RTA1: (PANDA::TONY)

$ logout
TONY logged out at 17-FEB-2026 11:46:44.93

[Connection broken, back at node PANDA]
%Link broken at PC 75152. Error code 0: No special error
Last error in this process: Invalid source/destination designator
@
@logout
[H [JKilled Job 11, User TONY, TTY114 VOGON::SYSTEM, at 17-Feb-2026 11:47:03
Used 0:00:00 in 0:01:59

%REM-S-END, control returned to node VOGON::

$ sh net/old

OpenVMS Network status for local node 35.606 VOGON on FEBRUARY 17, 2026 11:47 AM

The next hop to the nearest area router is node 35.699 TNRTR.

Node Links Cost Hops Next Hop to Node

35.600 FAUNA 0 4 1 QNA-0 -> 35.630 KOALA
35.619 DINGO 0 4 1 QNA-0 -> 35.619 DINGO
35.629 PANDA 0 4 1 QNA-0 -> 35.629 PANDA
35.630 KOALA 0 4 1 QNA-0 -> 35.630 KOALA
35.636 RUSTY 0 4 1 QNA-0 -> 35.636 RUSTY
35.654 GALAH 0 4 1 QNA-0 -> 35.654 GALAH
35.687 DUGONG 0 4 1 QNA-0 -> 35.687 DUGONG
35.692 BROLGA 0 4 1 QNA-0 -> 35.692 BROLGA
35.699 TNRTR 0 4 1 QNA-0 -> 35.699 TNRTR
35.701 GUARD 0 17 4 QNA-0 -> 35.699 TNRTR
35.799 MBRTR 0 13 3 QNA-0 -> 35.699 TNRTR
35.1023 A35RTR 0 9 2 QNA-0 -> 35.699 TNRTR

Total of 12 nodes.

$ logout

SYSTEM logged out at 17-FEB-2026 11:47:27.84

Connection closed by foreign host
$
$opr
OPR>lcp show count
OPR>
11:47:40 [LCP] -- Counter Totals for All Servers --

Messages received: 36
Messages transmitted: 45
Messages retransmitted: 0
Sequence errors received: 0
Illegal messages received: 0
Illegal slots received: 0
Resource failures: 0
OPR>ncp show exec char
OPR>
11:47:53 NCP

Request # 9; Show Executor Node Characteristics Completed

Executor Node = 35.629 (PANDA)

Identification = DECnet-20 Version 4.0
Management Version = 4.0.0
Loop Count = 1
Loop Length = 127
Loop With = Mixed
Incoming Timer = 30
Outgoing Timer = 60
NSP Version = 4.0.0
Maximum Links = 65535
Delay Factor = 48
Delay Weight = 10
Inactivity Timer = 120
Retransmit Factor = 10
Routing Version = 2.0.0
Type = Nonrouting IV
Routing Timer = 600
Broadcast Routing Timer = 40
Maximum Address = 1023
Maximum Circuits = 20
Maximum Cost = 100
Maximum Hops = 16
Maximum Visits = 20
Maximum Broadcast Nonrouters = 64
Maximum Broadcast Routers = 32
Maximum Buffers = 80
Buffer Size = 576
Segment Buffer Size = 576
OPR>ncp show adjann\c
OPR>
11:48:03 NCP

Request # 10; Show Adjacent Nodes Summary Completed

No Information

OPR>ncp show known circ char
OPR>
11:48:13 NCP

Request # 11; Show Known Circuits Characteristics Completed

Circuit = NI-0-0

Service = Enabled
Cost = 4
Maximum Routers = 16
Router Priority = 5
Hello Timer = 15
Type = Ethernet

OPR>ncp show known circ count
OPR>
11:48:47 NCP

Request # 12; Show Known Circuits Counters Completed

Circuit = NI-0-0

521 Seconds Since Last Zeroed
226 Terminating Packets Received
244 Originating Packets Sent
0 Terminating Congestion Loss
0 Transit Packets Received
0 Transit Packets Sent
0 Transit Congestion Loss
0 Circuit Downs
0 Initialization Failures
0 Transmit packets discarded-blocksize exceeded
12104 Bytes Received
14914 Bytes Sent
227 Data Blocks Received
277 Data Blocks Sent
0 User Buffer Unavailable
OPR>exit
$^Ecease now
PANDA Will be shut down IMMEDIATELY
[Confirm]

[Timesharing is over]
17-Feb-2026 11:49:08 ACJ: System shutdown set by job 10, user OPERATOR, program CEASE, TTY5

OPERATOR - Wait for the message "Shutdown complete" before
entering commands to PARSER.
$[ni20_cmdchk: Illop=0 wd=4,,0 qe=164251]
[dpni20-W: Deleting "enp0s3" multicast entry: ff:ff:ff:ff:ff:ff]

[dpni20-W: "enp0s3" SIOCDELMULTI failed - No such file or directory]

[dpni20-W: "enp0s3" Multicast delete failed]
[ni20_cmdchk: Illop=0 wd=4,,0 qe=164261]

SJ 0: OPR>Killed Job 1, User OPERATOR, TTY13, at 17-Feb-2026 11:49:08
SJ 0: Used 0:00:00 in 0:09:01
[dpni20-W: Deleting "enp0s3" multicast entry: ab:0:0:1:0:0]

[dpni20-W: "enp0s3" SIOCDELMULTI failed - No such file or directory]

[dpni20-W: "enp0s3" Multicast delete failed]
[ni20_cmdchk: Illop=0 wd=4,,0 qe=164061]
17-Feb-2026 11:49:10 HSYS: Shutdown complete
[HALTED: FE interrupt]
KLH10> Are you sure you want to quit? [Confirm]Shutting down...Bye!

I have also tried building both the KLH10 versions on the Raspberry Pi 3 Model B Plus but get a "Device or Resource busy" error from dpni20 when it tries to access eth0 upon startup and a "***BUGCHK KNIADR***" back in TOPS-20. This is even with ethernet capabilies enabled and dpni20 suid root,, running KLH10 as root.

Either something is amiss with networking on the Pi - or I am missing something obvious.

Any Ideas?

Tony

David Todd

unread,

Feb 17, 2026, 7:15:25 AMFeb 17

to Tony Nicholson, PiDP-10

On 2/16/26 9:45 PM, Tony Nicholson wrote:
> This is using the pcap interface capability on the NI device to attach
> to the Pi's eth0 interface. I have also tried bridging a tap
> interface - with the same results. All my other simulator instances
> (VAX, PDP-11) running on Raspberry Pis or macOS work with pcap to the
> Ethernet interface (eth0) - and this is my preferred way of doing this.

Tony,
I'm not running DECnet, just TCP, so can't be directly helpful on this.
But I do have one observation that suggests something to try.

I've noticed on my Pi-5, and comparing between a desktop Mac Mini and
laptop Mac, that assigning the DEC20 interface to the PRIMARY (that is,
fastest or only) network interface, leads to periodic BUGINFs and
eventually network failure on the DEC20 guest.

So on my Pi-5 and Mac Mini (running gigabit EN), I assign the DEC20 pcap
to the WLAN interface and the DEC20 network interface runs reliably for
days. I use my laptop (which has just a WLAN interface) only
occasionally for DEC20 work and for limited times, and I almost always
end up with BUGINFs and eventually failures.

So if you have two interfaces on your Pi, you might try reversing the
DEC20 pcap assignment to put the DEC20 on the WLAN.

I'm hoping Jayjwa will pick up this thread for you: he runs DECnet and
has a great deal of experience with it.

David

Tony Nicholson

unread,

Feb 17, 2026, 3:33:25 PMFeb 17

to PiDP-10

David,

On Tuesday, February 17, 2026 at 11:15:25 PM UTC+11 hdt...@gmail.com wrote:

[snip]

I'm not running DECnet, just TCP, so can't be directly helpful on this.
But I do have one observation that suggests something to try.

I've noticed on my Pi-5, and comparing between a desktop Mac Mini and
laptop Mac, that assigning the DEC20 interface to the PRIMARY (that is,
fastest or only) network interface, leads to periodic BUGINFs and
eventually network failure on the DEC20 guest.

So on my Pi-5 and Mac Mini (running gigabit EN), I assign the DEC20 pcap
to the WLAN interface and the DEC20 network interface runs reliably for
days. I use my laptop (which has just a WLAN interface) only
occasionally for DEC20 work and for limited times, and I almost always
end up with BUGINFs and eventually failures.

So if you have two interfaces on your Pi, you might try reversing the
DEC20 pcap assignment to put the DEC20 on the WLAN.

Wireless LAN is not an option - since it doesn't behave exactly like physical

Ethernet. Running a protocol like DECnet changes the MAC address

to something like aa:00:04:00:xx:yy (where xx:yy are determined by the DECnet

node address). If the MAC address of a WLAN interface changes, it

will sever the association with your wireless access point (and break the

connection).

Tony

David Todd

unread,

Feb 18, 2026, 6:56:34 AMFeb 18

to Tony Nicholson, PiDP-10

Tony,

On 2/17/26 3:33 PM, Tony Nicholson wrote:

If the MAC address of a WLAN interface changes, it

will sever the association with your wireless access point (and break the

connection).