[TUHS] Harvard and Von Neumann Architectures and Unix

[Dave Horsfall]

On Sat, 25 Nov 2017, William Cheswick wrote:

> On CDC machines, the return jump (RJ) instruction generally used to call 
> subroutines deposited a jump instruction (EQ B0,B0,caller+1) in the 
> called routine and jumped to the word after it.  Clearly, languages like 
> Pascal didn’t use that.

Ahhh; that brings back fond memories of my Cyber-72 days, and how easily 
we CompSci kiddies broke into KRONOS...[*]

One of my favourite machines was the PDP-8; the JSR instruction planted 
the return address in the first word and jumped to the second word, with a 
return being done (IIRC) by an indirect jump to the first word. 
Recursion?  What's that?

[*]
Can't remember it now, but (on an LA-36 Duckwriter) it was something like:

     COMMON POOL
     RELEASE POOL
     (intr)

     (Could be abbreviated to "COMMO POO" and "REL POO" for those with a
     sick sense of humour, which was most of us.)

and you got system privileges...

-- 
Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."