Date: Tue, 28 May 1996 00:23:56 +0200 (MET DST) From: Tomas Klockar <dateck@ludd.luth.se> To: se@zpr.uni-koeln.de (Stefan Esser) Cc: terry@lambert.org, hackers@FreeBSD.org Subject: Re: SCSI hostadapter Message-ID: <199605272223.AAA04417@father.ludd.luth.se> In-Reply-To: <199605272131.AA10042@Sparcy42> from Stefan Esser at "May 27, 96 11:31:18 pm"
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According to Stefan Esser: > 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 ... That might be because of peoples lazyness, who might use linux instead or just go and buy a new SCSI-card. I don't think all people are on this mailinglist. It might also be that theese cards are pretty rare. The reason I'm on this list is that I couldn't find support for this card and that I belive that I have the knowledge to make a driver for it. Otherwise I would just have bought a new card. Or maybe ignored the disc since I'm using it for DOS. /Tomas -- Tomas Klockar can be found at the following adresses: Kårhusvägen 4, 2:43 | Furuvägen 102 | dateck@ludd.luth.se 977 54 Luleå | 871 52 Härnösand | dateck@solace.mh.se Tel: +46-920-229391 | Tel: +46-611-13393 | d94-tkl@sm.luth.se
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