[TUHS] What It Takes to Read Lions in 2026

[segaloco via TUHS]

On Tuesday, July 28th, 2026 at 10:14, Will Senn via TUHS <tuhs at tuhs.org> wrote:
 
> Lions is great, but today's reader needs more of a leg up. I think it
> illustrates how much architectural knowledge his original audience could
> take for granted. Nearly fifty years later, recovering that context has
> become part of reading the book. So, reading through Lions in 2026 is an
> archaeological dig, really :). That said, if you're planning to read
> Lions with any depth, be sure to minimally have on hand:
> 
> * Lions Commentary
> 
> * Lions Source Code
> 
> * PDP-11/40 Processor Handbook
> 
> * KT11-D Memory Management Option User Manual
> 
> * Repeatable notes for setting up a working lab
> 
> Later,
> 
> Will
> 

For the record, the intro does indicate what auxiliary knowledge may be necessary, pointing the reader to the manual, several papers such as C tutorials and UNIX for Beginners, as well as listing knowledge of the following PDP-11 hardware useful:

- PDP11/40
- RK05
- LP11
- PC11
- KL11

You also do get a bit of hardware exposition, albeit not too much, in Chapter 2.

This implies having the PDP-11 Peripherals Handbook on hand would also be helpful.  Naturally our biases allow us to overlook this, but having both the UNIX Assember Manual and C Reference Manual on hand would be helpful to the uninitiated as those are the two languages at play in the source volume.  Not sure how necessary this would be in practice but UNIX is an ASCII system, so non-ASCII-ites, however rare these days, would be going in with some unhelpful biases, but I don't know if that would peg the ASCII standard as required context.  I'm a sucker for building complete reference documentation graphs...so I'm going to hold my urge further for now.

Still, it would be an interesting exercise to pursue the full graph of primary references needed to establish a normative reference graph for Lions's Commentary.

Will, I don't know if this would be a comparable follow-on project, but there is the Program Description document published with USG UNIX that serves as another detailed analysis of the UNIX kernel[1] that may be worth inspecting with a similar lens.  By the way, I have a later hardcopy of [1] issued with Program Generic 3.  Unfortunately its just a reprint of the Program Generic 2 version and does not include the kernel changes in PG3, but it is complete, so I plan on scanning it in my next round of documents.

- Matt G.

[1] - unix_program_description_jan_1976.pdf