wiz@xroads.UUCP (Mike Carter) (07/22/89)
After receiving much mail and responses I've come to the undenyable conclusion that all of these projects would best be integrated into some DAC's and fed into a computer. WIth all of the measurement and conversions required by the sensors, it'd be easier interpreting the data via a real-time program . Now comes the choice. A small enough box (max dimensions are 2' x 2' x 4" to house the motherboar) is one limitation. The next is finding a monitor or small B&W or color monitor (perhaps a mini T.V. but I suspect most of them are not built well enough to withsatnd a month or two on Phoenix roads). What I'm hoping is that someone has information on a "computer" that is in production that would fit this description. I've considered building my own out of a Z8 or that one uP Intel makes with tiny basic on board. Considering the options, a device driver for a monitor and the bios needed to faciliate all this would almost make the project moot due to the benefits/time req'd . The ubiquituous (sp) Commodore computers come to mind and I was very fluent in the Vic-20 and C-64 machine language ..although very limited these would suffice. However, the commodes don't use standard I/O for devices like disks etc. SO it boils down to this list; (1) FIt in the 2' x 2' x 4" size limitation (2) Be able to readily drive a composite video monitor (3) Accept standard type I/O (e.g SCSI) (4) Cost less than $500.00 ALso...how about a 5-10 meg H.D. that's cabale of withstanding lots of bumps and the motion of a vehicle in traffic ? (am I dreaming or is this wishfull thinking?_ -- ============================================================================= = Mike Carter N7GYX, Phoenix AZ| Q: Why did the Chicken cross the road ? = = hplabs!hp-sdd!crash!xroads!wiz| A: To ESCape the Main Menu . = =============================================================================
erk@americ.UUCP (Erick Parsons) (07/23/89)
>From: wiz@xroads.UUCP (Mike Carter) Message-ID: <771@xroads.UUCP> >ALso...how about a 5-10 meg H.D. that's cabale of withstanding lots of >bumps and the motion of a vehicle in traffic ? >(am I dreaming or is this wishfull thinking?_ Mike, I read with interest this article about Seagate Hard drives in the comp.sys.amiga newsgroup about a week ago. There has been an ongoing debate about the 'Stiction' problem prevalant in the Seagate HD's caused in part by system software that does not park the heads. The head ends up resting on the media, essentially gluing the head to the platter causing loss of spinup on reboot... Anyway here is the Article: ---------------------previously posted article----------------------- Whatever the disk drive "plated media" material IS, it's unbelievably hard. I opened one of my defective ("stiction") Seagate ST251 drives and performed some experiments on it: 1) lightly touching the platter surface with a screwdriver blade while the disk was spinning left NO evidence of the contact. 2) blowing cigarette smoke onto the platters while running DiskPerf caused no noticeable effect. 3) spitting onto the rotating platter during DiskPerf (yeah, I'm really getting mean here! :-) brought up a R/W error requestor; manually spinning the shaft and moving the head assembly while wiping the platter with a Kleenex (tm) soaked with Ronsonol (tm) lighter fuel cleared up the R/W error as verified by another DiskPerf run. 4) depositing a fingerprint on the platter, manually spinning the main spindle shaft, and positioning the heads so they'd ride over the fingerprint, a VERY noticeable drag was encountered at the point of contact with the fingerprint. Continuing to spin the main shaft, the heads eventually erased all evidence of the fingerprint; the drive didn't pass a DiskPerf until I again cleaned the platter (and, by implication, the head) with Ronsonol. 5) my home microscope only goes to 100x, so I couldn't see the "white worms" as I did at the HD repair place. But careful examination of the drive clearly shows the "heads" ARE in contact (buffered by the lubrication) with the platter surface during normal operation (determined by sighting across the disk surface looking into a high-intensity lamp). The head sled is a rectangular block about 1/8"x1/4" and about .050" thick, whose R/W surface is as super-polished as the surface of the platters. 6) Final experiment: moved the heads to PARK position and waited awhile; there was VERY DEFINITE RESISTANCE ("stiction") when attempting to move them later. Moved the heads to the middle of the platter and waited awhile; there was NO noticeable resistance when attempting to move them later. The anecdotes posted by our "anonymous" poster tend to suggest "old" disk technology, pre-Whitney and possibly pre-Winchester; not relevant TODAY. The "stiction" problem with the drives is one characterized by physics and NOT by chemistry; more specifically: fluidics. If you haven't done so already, do the simple experiment I described in the previous posting on this subject (with the two glass plates (or microscope specimen slides) and a drop of water). And, for everyone's entertainment, amusement and enjoyment, I'll bring the drive to this week's BADGE meeting where we'll attempt to induce a head crash after everyone's had a chance to SEE the insides of the drive for themselves. Try to dream of a way to make it fail; I've already dropped it and wacked it on the side with a wooden mallet while it was operating ... it continues to function after clearing the momentary R/W error. As I've said before, the basic design of the drive IS good, it's only the manufacturing flaw regarding lubrication that is causing all the problems. Thad Floryan [ thad@cup.portal.com (OR) ..!sun!portal!cup.portal.com!thad ] -- ------------------ // -----------Cut-Here---------------------------------- Erick Parsons // Words for the wise: *If it works don't fix it.* Sacramento Ca // mail to: ...pacbell!sactoh0!americ!erk ------------- \\// --------------------------------------------------------