From mboxrd@z Thu Jan 1 00:00:00 1970 From: bqt@update.uu.se (Johnny Billquist) Date: Thu, 24 Mar 2016 12:37:31 +0100 Subject: [TUHS] Early non-Unix filesystems? In-Reply-To: <002e01d185c1$502c06e0$f08414a0$@ronnatalie.com> References: <56F3BEAE.9060903@update.uu.se> <002e01d185c1$502c06e0$f08414a0$@ronnatalie.com> Message-ID: <56F3D17B.5080002@update.uu.se> On 2016-03-24 12:35, Ron Natalie wrote: > >> Ok. Color me stupid, but I don't get it. I totally do not understand how this locks anything out. > > I misstated that a bit. The issue is if the next instruction is also an SPL instruction, then interrupts never get enabled. So if you have a run of SPL instructions, interrupts are locked out for the duration. If you can fill your address space with SPL instructions (provided the OS doesn't fail in the process), you can cause an uninterruptable loop. Interupt includes the HALT switch on the front. You have to use the BUS RESET to jab it out of its catatonic state. Hmm. Ok. Gotta check this out. Thanks for the details. Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol