From mboxrd@z Thu Jan 1 00:00:00 1970 From: dave@horsfall.org (Dave Horsfall) Date: Sun, 26 Nov 2017 10:15:23 +1100 (EST) Subject: [TUHS] Harvard and Von Neumann Architectures and Unix In-Reply-To: References: <20171124214342.A4A8818C0D0@mercury.lcs.mit.edu> <201711242150.vAOLoHCg026295@darkstar.fourwinds.com> Message-ID: 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."