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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!nntp.coast.net!howland.reston.ans.net!Germany.EU.net!Dortmund.Germany.EU.net!interface-business.de!usenet From: j@ida.interface-business.de (J Wunsch) Newsgroups: comp.unix.bsd.misc Subject: Re: Comments on new 4.4 Design book? Date: 8 Jul 1996 08:49:40 GMT Organization: interface business GmbH, Dresden Lines: 23 Message-ID: <4rqi34$39f@innocence.interface-business.de> References: <4rhnr0$lef@picasso.op.net> <4rjpi9$hh@anorak.coverform.lan> Reply-To: joerg_wunsch@interface-business.de (Joerg Wunsch) NNTP-Posting-Host: ida.interface-business.de X-Newsreader: knews 0.9.6 X-Phone: +49-351-31809-14 X-Fax: +49-351-3361187 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E brian@awfulhak.demon.co.uk (Brian Somers) wrote: > It's red and has the Daemon on the front, but apart from that I havn't > read any yet. I'm still wading through "Unix Internals" by Valhalia. Ah, about the same as for me. ;-) > Has anyone any comments on that ? One of the exercises at the end of > chapter 2 suggests that the PICs in a PC have no way of prioritizing > interrupts. I'm sure I read that they did in PC-Intern. They can. Seems i've been skipping the excercises. Anyway, the PIC priorization is not that useful. Theoretically, you can reprogram the PIC to mask unwanted interrupts, but it costs a lot of CPU cycles. (IO operations are among the most expensive ones on everything >= i486.) I believe, 386BSD used the PIC to implement the spl's. -- J"org Wunsch Unix support engineer joerg_wunsch@interface-business.de http://www.interface-business.de/~j