Fast Start
Prerequisites
You need an SD-Card formatted as FAT-32 and copy your disk image files
to any directory. Make sure the disk image files you copy are boot images
for the DU device at the standard address. In my example I have copied
the diskimage files to the directory named diskimages. When you
insert an SD-Card with just one FAT-32 formatted partition the units
will not be attached and they will be offline for the PDP-11.
]
]show units
Unit 0 (0x4D90) is not attached
Unit 1 (0x4DA0) is not attached
Unit 2 (0x4DB0) is not attached
Unit 3 (0x4DC0) is not attached
]dir
Directory of /
A Cl:00000000 <Volume> FILES
Cl:00000086 <DIR> diskimages
]dir diskimages
Directory of /diskimages
A Cl:0000008B 1'000'448'512 2.11BSD_rq.dsk
A Cl:000077D2 159'385'600 rsx11mplus_4_6_bl87.dsk
A Cl:00008AE3 10'485'760 rsx11mphack.dsk
A Cl:00008C25 10'485'760 rt11v57dl4.dsk
]
In my example I will just attach the RSX-11Mplus image to unit 0.
]attach unit0 diskimages/rsx11mplus_4_6_bl87.dsk
Finddrive with size 0x0004C004
Attach - Full File Name:'diskimages/rsx11mplus_4_6_bl87.dsk'
/diskimages/rsx11mplus_4_6_bl87.dsk
]show unit
Unit 0 (0x4D90) is attached to file (0x6A56) /diskimages/rsx11mplus_4_6_bl87.dsk
File is contiguous.
Fragments of file
Start:0029AA34 Length:0004C040
Drive has 0x0004C004 blocks, 0x11 sectors/track, 0x0F tracks/cylinder and 0x04C8 cylinders
Drive type/flags and name 0x00/0x01 RD54
Unit 1 (0x4DA0) is not attached
Unit 2 (0x4DB0) is not attached
Unit 3 (0x4DC0) is not attached
]
As you can see the disk image is recognised as RD54 and has been found to be contiguous.
Loading Bootstrap Loader
In case you have no boot ROM, or your boot ROM does not provide a bootstrap loader for DU you can install a simple bootstrap loader via the MSCP Emulator to the memory of your system.
]load 0100000 duboot
Writing 64 Words of DUBOOT to 00100000, use 100004g
]
The bootstrap loader is a copy of Dan Norths DU bootstrap loader which can be found at his collection of bootstrap loaders
https://ak6dn.github.io/PDP-11/M9312/
I have not stripped it from is pre and post amble. Therfore on the host system
you need to start the bootstrap loader at the adress indicated in the above
message in our case you enter 100004g at the ODT prompt.
You must use a load address higher than 1000008 because the bootstrap loader assumes that the instruction ‘MOV PC, R3’ sets the N-flag in the processor status.
The PDP-11 should now boot from Unit 0. You can as well change the unit number by entering the desired number at location 1000108 before you start the bootstrap loader.
@100000/042125
00100002/000176
00100004/000261
00100006/012700
00100010/000000 <---- here you enter a non-standard unit number
00100012/012701
00100014/172150 <---- here you enter a non-standard device address
00100016/010704
@
Now you should see the OS start. Note that it might take some time between
entering g and the first output, depending on the amount of memory you have
installed. In my system with a M8192 CPU and 4Mbyte of RAM it takes 15
seconds. To start the loaded boot strap loader enter 100004g.
@100004gSX-11M-PLUS V4.6 BL87 2044.KW System:"RSXMPL"
>RED DU:=SY:
>RED DU:=LB:
>RED DU:=SP:
>MOU DU0:"RSX11MPBL87"
>@DU:[1,2]STARTUP
>; PLEASE NOTE
>;
>; If you have not yet read the system release notes, please do so
>; now before attempting to perform a SYSGEN or to utilize the new
>; features of this system.
>;
>;
SET -- Inquire cannot determine terminal type
>;
>; Please ignore any random characters that may have printed on your
>; terminal just now. They came from a SET /INQUIRE=TI: command.
>; Evidently your terminal does not recognize escape sequences.
>; This will not affect the running of this command file.
>;
>* Please enter time and date (HH:MM DD-MMM-YYYY) [S]: 10:56 1-jun-2026
>TIME 10:56 1-jun-2026
>ACS SY:/BLKS=1024.
>CON ONLINE ALL
>ELI /LOG/LIM
>CLI /INIT=DCL/CTRLC/DPR="<15><12>/$ /"
>INS LB:[1,1]RMSRESAB.TSK/RON=YES/PAR=GEN
>INS LB:[1,1]RMSLBL.TSK/RON=YES/PAR=GEN
>INS LB:[1,1]RMSLBM.TSK/RON=YES/PAR=GEN
>INS $QMGCLI
>INS $QMGCLI/TASK=...PRI
>INS $QMGCLI/TASK=...SUB
>QUE /START:QMG
>INS $QMGPRT/TASK=PRT.../SLV=NO
>QUE LP0:/CR/NM
>START/ACCOUNTING
>CON ESTAT LP0:
>QUE BAP0:/BATCH
>QUE BAP0:/AS:BATCH
>@ <EOF>
>
Now enjoy the nostalgic feeling
RSX-11M-PLUS V4.6 BL87 (RSXMPL) 2044K UP 000:00:02 1-JUN-26 11:01:32
TASK= *IDLE* FREE= SY0:172815.
PARS
POOL=12912.:12966.:11. SECPOOL=426.:512.:83%
12912.:12966.:11. 426.:512.:83% SECPOL:P
SYSPAR:D
IN D RD.FF QB DRVPAR:D
8 I CU.11 MA GEN :D
57 R T:.11 GP
OU 1 . AAA .0
0 1 . TCC .
0K M . .PP .
!=!])+>+<>>
0*******127*****255*****383*****511*****638*****766*****894*****
PPD--DD---------------------------------------------------------
----------------------------------------------------------------
1022****1149****1277****1405****1533****1660****1788****1916****
ERRSEQ
0.
.
RSX-11M-PLUS V4.6 BL87 (RSXMPL) 1024K UP 001:00:00 18-JUN-26 08:40:58
TASK= *IDLE* FREE= SY0:172258.
PARS
POOL=12908.:12966.:8. SECPOOL=424.:512.:82%
12908.:12966.:8. 424.:512.:82% SECPOL:P
SYSPAR:D
IN: D MRTDV.F FF . QHB R DRVPAR:D
8 I CCTUF.C 11 . MRA M GEN :D
57K R RT:::.S 11 . GCP D
OUT: 1 .. AR AA P ..0 T
0 1 .. TE CC I .. 0
0K M .. .S PP P ..
!==!>])))+!<>+++<>>->>
0*******64******128*****192*****256*****320*****384*****448*****
EP-P-D----D--D--------------------------------------------------
----------------------------------------------------------------
512*****576*****640*****704*****768*****832*****896*****960*****
ERRSEQ
0.