Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!lll-tis!ames!oliveb!sun!pepper!cmcmanis From: cmcmanis%pepper@Sun.COM (Chuck McManis) Newsgroups: comp.sys.amiga Subject: Re: Hard Drive Questions (XEBEC) (longish) Message-ID: <42959@sun.uucp> Date: 24 Feb 88 01:05:15 GMT References: <883@isrnix.UUCP> Sender: news@sun.uucp Reply-To: cmcmanis@sun.UUCP (Chuck McManis) Organization: Sun Microsystems, Mountain View Lines: 81 Keywords: DMA A2090 Filesystem XEBEC In article <883@isrnix.UUCP> greg@isrnix.UUCP (Gregory Travis) writes: ><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> ><> This is a reposting, the original didn't seem to make it out <> ><> of Bloomington! Apologies to anyone who's seen it already. <> ><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> It did, just no one commented on it. Or maybe none of the comments made it back to bloomington. > 1) The drive is rated (according to the Xebec manual) at over 150K > bytes/second. Actual read transfer rate, going flat out, to my Amiga > seems to be around 25-30K, which stinks. Welcome to the world of the AmigaDOS filesystem! Yes it stinks, yes it is fixed by the Fast File system, no you can't get the Fast File system until 1.3 comes out and I have no idea of when that would be. > 2) I have noticed that when WRITING to the disk (say from Emacs See above. Writing is still less than optimal. > 2) Is there any possibility that the drive will work with a > A2090 DMA controller? I may buy a 2000 some day and I would like to > keep the Xebec. It is a "modified SCSI" (whatever "modified" means). Should if it talks *real* scsi, whatever that is. My guess would be that it will. Although it won't be any faster until the FFS arrives. > 3) Does anyone know what I have to send, and to whom (i.e. to SCSI.DEVICE > or DH0:), to park the drive? I would like to write a program which > sits in the background and parks the drive every 10 minutes or so. Only the Authors of the Driver for your particular disk know that, call Xebec. Sorry I can be more help here. > 4) Where can I get information on the controller itself? I would like to > know things like where in the address space the controller appears, > what the registers are and what bits do what (if this sounds wrong, > it's because I write PDP-11 UNIBUS drivers all the time and have never > written a 68000 driver). First read the expansion spec for the Amiga, primarily because where exactly the hardware appears will vary somewhat. Then get a technical manual from Xebec. Xebec is not on the net that I know of, maybe someone who has one and has gone through a similar process will respond. >Primarily, I am interested in improvements to the system software so that >any I/O related waits are due to waiting for the DRIVE to do >its work. I can't imagine why the drive would ever sit idle waiting for >the CPU to tell it what to do. Even if the filesystem is not optimized >for hard disks, shouldn't the disk be busy seeking all over the place? Why not get some of the public domain stuff like Matt's Packet Monitor and track down where you are spending your time. I think you will need to learn a lot more about the Amiga OS's internals which is not impossible but is beyond the scope of this article. Some pointers to help you along the way --> BOTH volumes of the Rom Kernel Manual, Read them cover to cover including the include files, three times. --> Rob Peck's book which has a decent overview of how the Amiga's OS is layered. --> The Kickstart Guide to the Amiga which has some more obscure Exec type information in it. ---> All of the include files/ Readmes/ Autodocs on the Native Developers Update disk ($20 from CATS, 1200 Wilson Dr, West Chester, PA, 19380) --> All I/O code that appears on any Fish disk, this includes Matt's device and handler routines, the Pipe: handlers, the simple SCSI hard disk driver and the example device from the RKMs If you have any specific questions after that please let us know :-) Seriously, the information is all available, it just isn't coalesed(sp?) real well. --Chuck McManis uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com These opinions are my own and no one elses, but you knew that didn't you.