Date: Mon, 27 May 1996 23:31:18 +0200 From: se@zpr.uni-koeln.de (Stefan Esser) To: Terry Lambert <terry@lambert.org> Cc: hackers@freebsd.org Subject: Re: SCSI hostadapter Message-ID: <199605272131.AA10042@Sparcy42> In-Reply-To: Terry Lambert <terry@lambert.org> "Re: SCSI hostadapter" (May 23, 15:13)
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On May 23, 15:13, Terry Lambert wrote: } Subject: Re: SCSI hostadapter } > I have a SCSI host adapter which I would like to use in freebsd } > The brand is NexStor NXT-82 } > Its a VL-Bus FAST SCSI-2 Host adapter } > Its using a a NCR 53C700-66 curcuit } > It memorymaps the data. } } I believe the NCR 53c7xx series (I don't recognize the "53C700-66" } in particular, though) are not supported because they are very } low end components, for which no one has written a driver. Hmmm, sorry, no, not really ;-) The 53c7xx family consists of the 700, which is the ancestor of all 7xx and 8xx chips. It has a smaller instruction set and lacks support for somce features, that had been added in the 710. (Most significantly the INTFLY, which lets the 53c710 and later continue processing after issuing an interrupt to the host CPU. The 700 stops on every interrupt, and waits for the CPU to restart it. The INTFLY feature is used to make the CPU poll for completed commands, while the NCR already talks to the next SCSI target.) } These are the same chips in AMD SCSI/Net ethernet/SCSI chips on } the motherboard of some Compaq systems. Umm, no, sorry. The decice in the AMD Combo chip seems to be based on the 53c90, but I have never actually seen a data book on it. But I know that it also lacks an INTFLY capability, i.e. the CPU has to drive it as an intelligent host adapter, while the NCR 53c710 and later are real independent processors working on a closed code loop, as long as no real exception stops them and makes the CPU clean up. } You should use another card (~US$75 for an NCR 8xx series, one } of the best available), or write a driver (for which you will need } another working machine, or another card, and docs for the 7xx } chips; on the plus side, yyou should be able to use the 8xx } driver as a template). The 710 driver would need mostly changes in the probe and attach code. A driver for the 700 would need a rewrite of the code executed by the NCR chip itself and changes to the driver code executed by the host CPU. If you got PCI, the the 53c810 is a cost effective choice. If you don't, well, then I'd rather buy a used Adaptec 1542 or some compatible BusLogic than spend hundreds of hours on a driver for obsolete hardware. There have been a total of four requests for a 53c7x0 driver over the last two years ... Regards, STefan -- Stefan Esser, Zentrum fuer Paralleles Rechnen Tel: +49 221 4706021 Universitaet zu Koeln, Weyertal 80, 50931 Koeln FAX: +49 221 4705160 ============================================================================== http://www.zpr.uni-koeln.de/~se <se@ZPR.Uni-Koeln.DE>
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