[TUHS] Some resources for V6/PDP/SIMH newbs like me

Wolfgang Helbig helbig at mailbox.org
Wed Jan 10 04:05:56 AEST 2018

Hi, Will

may I point to chapter 1.0 of my operating system lecture notes at:

among others, it explains the assembler language, together with the description of the instruction set


and finally the Unix Assembler Reference Manual(1) at

might help.

> Am 20.11.2017 um 20:20 schrieb Will Senn <will.senn at gmail.com>:
> All,
> While it's fresh, I thought I'd share some resources I've found helpful in learning about the venerable v6 as a relative newb...
> Learning Unix V6 in the modern era is an interesting and enormously educational experience. In the process of using it I have had to learn how to host it in a simulator (SimH in my case, but there are others), install it, communicate with it, configure it, build special files for it, attach devices to it, communicate with the devices attached to it and to SimH, build a kernel, install the kernel, boot the kernel, work with a variety of media intended to work with it, extend it, and so on. In addition, I have had to learn a bit about the PDP-11 (as arguably the most convenient architecture for learning about V6), about its architecture, its instruction set, its devices, its memory structure, and so on.
> None of this exploration would have been possible without the excellent work of Bob Supnik, Mark Pizzolato, and co. on the SimH pdp-11 simulator, the Simh mailing list, Warren Toomey and TUHS for making the bits available, the TUHS mailing list, PUPS, Bitsavers, and a slew of readily available documentation and texts including these notables:
> Setting Up Unix 6th Edition from the V6 Programmer's Manual
> The Unix V6 Programmer's Manual in its entirety
> The SimH and SimH PDP-11 Manuals
> A large number of blogs with SimH specific V6 installation logs
> The V6 Source Code and man pages (don't forget to install man - the 1bsd version works, and is superior)!
> The DEC PDP-11/05-10-35-40 1973 Handbook (the 11/40 handbook is not as detailed with respect to memory management)
> Lions's Commentary on the Sixth Edition source code
> Now that I'm over the beginner's hump, so to speak, I'm exploring things differently and I thought I'd share some resources that I am currently finding useful and interesting in my explorations...
> To bone up on assembly language, Lions's commentary is exceptionally helpful in explaining assembly as it is implemented in V6. The manual itself is really thin, and the source is a bit cryptic, for the newcomer. Lions explains the idioms used in the main source of V6. However, without a background in assembly language, Lions is pretty meaningless, so I went looking for something that was PDP specific that would bridge the gap and help me understand Lions's words. I found a number of texts that were really good. Most require a working RT11 instance to actually try out the coding examples and do the exercises (SimH and Bitsavers to the rescue):
> Arthur Gill - Machine and Assembly Language Programming of the Pdp-11
> Charles A. Kapps and Robert L. Stafford - Assembly Language for the PDP-11
> Glenn H. MacEwan - Introduction to Computer Systems: Using the PDP-11 and Pascal
> James F. Peters - The Digital Way: Macro-11 Assembler Programming (PDP-11)
> Michael G. Schneider - The Principles of Computer Organization: With Assembly Language Programming for the PDP-11
> PDP-11 Processor Handbook (pretty much any edition)
> Thomas A. Frank - Introduction to the PDP-11 and its Assembly Language
> All of these are useable with a running RT11 instance. But, I think the Peters and Frank books are the standouts. Peters because all of the exercises that I have tried (dozens) have worked as printed and Frank because he is rigorous in his treatment of the subject and builds up from digital logic all the way through program execution. Frank is an excellent complement to Lions work because he explains the details that Lions assumes.
> To learn about digital logic, and a special thanks to Warren for his work on Crazy Small CPU, I have been introduced to logisim. It is a great playground for exploring digital logic. I had no idea that a sketchpad for digital logic simulation was available and accessible to the layperson. Logisim development stopped around 2014 and while there are a number of successors out there, I am using logisim-evolution:
> https://github.com/reds-heig/logisim-evolution
> The rabbit trails never seem to end... in order to learn how to use logisim, I went through the excellent tutorial and then went looking for a book of experiments in digital logic and found:
> digital computer lab workbook from 1969
> http://bitsavers.trailing-edge.com/pdf/dec/handbooks/Digital_Computer_Lab_Workbook_1969.pdf
> digital equipment corporation computer lab teacher's guide from 1968
> http://www.so-much-stuff.com/pdp8/pdf/ComputerLabTeachersGuide.pdf
> These two are useable with very little modification as a source of digital logic exercises that work great with logisim and are related to the architectural lineage of the PDP-11.
> These resources fit together nicely in my pursuit to better understand digital logic, the pdp-11, assembly language, and unix v6. In sum:
> Source code for v6 for what really is supposed to happen in v6 operation
> Lions for understanding Unix V6 sources and for unix assembly language information
> PDP-11 Hanbook for quick reference on PDP-11 assembly language instruction set
> Frank for assembly language details and for details on digital logic and its relationship to the PDP-11 architecture.
> Logisim to test logic constructs
> The digital lab workbook for practice with digital logic
> Later,
> Will
> -- 
> GPG Fingerprint: 68F4 B3BD 1730 555A 4462  7D45 3EAA 5B6D A982 BAAF

Wolfgang Helbig
Stauferstr. 22

71334 Waiblingen

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