Andrzej Popielewicz Phd

Applied Informatics Division
Institute of Physics UAM

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Using simh, pdp11 emulator under Coherent 4.2.x 

 What You need

  • pdp11 binary Download

  • original pdp boot images , download it from TUHS

Other emulators available : pdp1, i1401(IBM computer from times of UNIVAC and von Neumann)

Installation /Running

  • copy pdp11 binary to /usr/bin

  • create own directory for example /pdp11

  • cd /pdp11

  • create emulator startup file pdp11.start, details as above :

  • type : pdp11 pdp11.start

  • type few commands to boot the image : details as above


  • Boot images tested: v7_rl02,v7_rk05,Ultrix-11 3.x,2.9BSD

  • You can compile using cc or pcc

  • most Unix commands work fine , even vi etc

  • how it compares to apout ? apout is a user level emulator, it allows to run programs only. simh emulator allows to boot original operating system

Hints :

1)CTRL/D to switch to multiuser mode after booting image(after prompt # appears)

2)CTRL/E to comeback to simulator(or how to leave the booted OS)

3)set cpu 3072K (use in Ultrix-11 startup file), if message “too big” is produced

4)if login in multiuser state fails , reboot and change password of root using passwd in single user mode) and then CTRL/D

5)if visual problems with vi in Ultrix , start emulator in xterm

License : non-commercial use only

Author :

Bob Supnik