From mboxrd@z Thu Jan 1 00:00:00 1970 From: jcea@jcea.es (Jesus Cea) Date: Thu, 05 Jun 2014 15:34:31 +0200 Subject: [TUHS] Gnu/Stallman (was Bugs in V6 'dcheck') In-Reply-To: <1968586D-53E6-4C90-A844-E975FA6FA5AF@coraid.com> References: <201406020209.s5229Q5o006174@stowe.cs.dartmouth.edu> <20140602142446.GM18282@mercury.ccil.org> <20140605073112.GD10373@attic.nerdnet.nl>, <1401959824.53903590d25f5@www.paradise.net.nz> <1968586D-53E6-4C90-A844-E975FA6FA5AF@coraid.com> Message-ID: <539071E7.9040807@jcea.es> On 05/06/14 13:26, Brantley Coile wrote: > This method wasn't original to me. It was common practice at the > time. I assume this the technique used by AmigaDOS. I have no direct knowledge of AmigaDOS, but since there was no hardware protection between processes and all processes shared the same address space, context switching COULD BE just "store process registers, including stack pointer and Program Counter, for process A", "restore process registers, including stack pointer and program counter from process B". Certainly I did this in the 8 bit era (well, 6502 CPU have the stack in a fixed position but only just 256 bytes long, so I just copy it around when doing context switching) and in Atari ST (68000 based computer). -- Jesús Cea Avión _/_/ _/_/_/ _/_/_/ jcea at jcea.es - http://www.jcea.es/ _/_/ _/_/ _/_/ _/_/ _/_/ Twitter: @jcea _/_/ _/_/ _/_/_/_/_/ jabber / xmpp:jcea at jabber.org _/_/ _/_/ _/_/ _/_/ _/_/ "Things are not so easy" _/_/ _/_/ _/_/ _/_/ _/_/ _/_/ "My name is Dump, Core Dump" _/_/_/ _/_/_/ _/_/ _/_/ "El amor es poner tu felicidad en la felicidad de otro" - Leibniz -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 538 bytes Desc: OpenPGP digital signature URL: