olaf@cbnewsc.ATT.COM (olaf.henjum) (10/20/89)
Thanks very much to all of you who responded to my last posting.
I now have more answers than I need to my questions on BASIC and Lotus 1-2-3
(indeed, several variations on the same answers, both of which have already
been posted to the net by somebody else).
However,
(1) I could still use some more feedback on "good" implementations
of COBOL for PCs.
So far, no two people have made the same recommendation!
I also have a couple of other "beginner" questions which I'd like to
get some confirmation on (i.e. I think I already know the answer, but
it would be nice to have it confirmed):
(2) My understanding is that frequent power cycling (i.e. shutting off
the PC/AT whenever it's not in use) cannot cause damage to or
in any other way hasten the wearing out of any part of the PC.
Is this really true? Or is it better for the machine to leave
it running 24 hours a day as much as possible?
(3) I've gotten conflicting information on the necessity of manually parking
the hard disk heads before powering down the machine. Some
people have told me that one should ALWAYS do this for ANY kind
of PC or PC-clone. Others have said that this is necessary only
for the PC/XT due to a design flaw in the first XTs that came out,
and that AT machines automatically park the heads correctly whenever
they're powered down (i.e. there's no need to manually run some utility
program to do it). I would tend to believe the second
account, but again it would be nice to have it confirmed.
As before, any help you might be able to provide to any one of these
questions would be GREATLY appreciated!
-- Olaf Henjum (arpa!att!ihlpf!olaf)Ralf.Brown@B.GP.CS.CMU.EDU (10/21/89)
In article <4005@cbnewsc.ATT.COM>, olaf@cbnewsc.ATT.COM (olaf.henjum) wrote: >(3) I've gotten conflicting information on the necessity of manually parking > the hard disk heads before powering down the machine. Some > people have told me that one should ALWAYS do this for ANY kind > of PC or PC-clone. Others have said that this is necessary only > for the PC/XT due to a design flaw in the first XTs that came out, > and that AT machines automatically park the heads correctly whenever > they're powered down (i.e. there's no need to manually run some utility It's not the computer, it's the drive. If you have an autoparking drive (goes "clunk" when the power is shut off), then you don't need to manually park the drive. Most XT drives need to be manually parked, most AT drives are autopark (I think the split is stepper motors need manual parking, voice coils park themselves). I normally park my autopark drive anyway, so it doesn't hit the endstop as hard when the power is shut off. -- UUCP: {ucbvax,harvard}!cs.cmu.edu!ralf -=-=-=-=- Voice: (412) 268-3053 (school) ARPA: ralf@cs.cmu.edu BIT: ralf%cs.cmu.edu@CMUCCVMA FIDO: Ralf Brown 1:129/46 FAX: available on request Disclaimer? I claimed something? "How to Prove It" by Dana Angluin 1. proof by example: The author gives only the case n=2 and suggests that it contains most of the ideas of the general proof
unkydave@shumv1.uucp (David Bank) (10/22/89)
DISCLAIMER: This is ** NOT ** a flame
Piece of advice to Olaf Henjum. When next you meet these people
telling you these things about PCs, don;t let them sell you any
bridges.
Over time, frequent flipping power on and off CAN take its
toll on the PC's power supply on/off switch. It is just like any
other moving part and is subject to wear. As is the power supply
itself. Spikes and momentary power-up surges can cause component
degredation and that, combined with age, can make them fail.
So yes, eventually these parts will fail. Is it likely to
damage your computer's innards in any way?? I'd be more worried
about the dust collecting in there.
So...the PC/AT auto-parks hard drives on power-off. Gee, I
bet the people at IBM would be interested to know that. Sorry,
the sarcasm just slipped.
Auto-parking is a function of the HARD DISK itself. PC/XTs
can have auto-parking hard drives or not. Same for PC/ATs. It all
depends on the hard disk. Check with the manufacturer to find
out. Generally speaking, RLL drives are intrinsically auto-park,
while most MFM drives are not.
Next time you see these people, Olaf, tell 'em Unky Dave
said they don't know what in the hell they're talking about.
And that IS a flame (but not at you).
Unky Dave
unkydave@shumv1.ncsu.eduralf@b.gp.cs.cmu.edu (Ralf Brown) (10/23/89)
In article <4267@ncsuvx.ncsu.edu> unkydave@shumv1.ncsu.edu (David Bank) writes: }depends on the hard disk. Check with the manufacturer to find }out. Generally speaking, RLL drives are intrinsically auto-park, }while most MFM drives are not. My MFM ST4051 is most definitely autopark. I think the deciding factor is whether the head positioner is a stepper motor (nonparking) or voice coil (autoparking). -- {backbone}!cs.cmu.edu!ralf ARPA: RALF@CS.CMU.EDU FIDO: Ralf Brown 1:129/46 BITnet: RALF%CS.CMU.EDU@CMUCCVMA AT&Tnet: (412)268-3053 (school) FAX: ask DISCLAIMER? | _How_to_Prove_It_ by Dana Angluin What's that?| 2. Proof by Intimidation: "Trivial."
unkydave@shumv1.uucp (David Bank) (10/23/89)
In article <6626@pt.cs.cmu.edu> ralf@b.gp.cs.cmu.edu (Ralf Brown) writes: >In article <4267@ncsuvx.ncsu.edu> unkydave@shumv1.ncsu.edu (David Bank) writes: >}depends on the hard disk. Check with the manufacturer to find >}out. Generally speaking, RLL drives are intrinsically auto-park, >}while most MFM drives are not. > >My MFM ST4051 is most definitely autopark. I think the deciding factor is >whether the head positioner is a stepper motor (nonparking) or voice coil >(autoparking). >-- >{backbone}!cs.cmu.edu!ralf ARPA: RALF@CS.CMU.EDU FIDO: Ralf Brown 1:129/46 >BITnet: RALF%CS.CMU.EDU@CMUCCVMA AT&Tnet: (412)268-3053 (school) FAX: ask >DISCLAIMER? | _How_to_Prove_It_ by Dana Angluin >What's that?| 2. Proof by Intimidation: "Trivial." Well, since RLL drives practically HAVE to be voice-coil, that sorta proves my statement, doesn't it????? Fact is, I can't think of any RLL drives that use stepper motors. Might be a handful out there. Anyone know for sure??? Maybe some of the early ones??? Stepper motors CAN be auto-parking. You just have to provide a power source after the main one is shut off and instructions to the motor to step to the landing zone. Voice-coil just returns to the retracted position due to its design. That's why most stepper-driven drives aren't auto-park -- its a pain to make them do that. Unky Dave unkydave@shumv1.ncsu.edu
scott@csusac.csus.edu (Skitzer) (10/23/89)
In article <4274@ncsuvx.ncsu.edu> unkydave@shumv1.ncsu.edu (David Bank) writes: >In article <6626@pt.cs.cmu.edu> ralf@b.gp.cs.cmu.edu (Ralf Brown) writes: >>In article <4267@ncsuvx.ncsu.edu> unkydave@shumv1.ncsu.edu (David Bank) writes: >>}depends on the hard disk. Check with the manufacturer to find >>}out. Generally speaking, RLL drives are intrinsically auto-park, >>}while most MFM drives are not. >sorta proves my statement, doesn't it????? > > Fact is, I can't think of any RLL drives that use stepper motors. >Might be a handful out there. Anyone know for sure??? Maybe some >of the early ones??? > My Seagate ST-238 RLL isn't autoparking...Don't know if it's stepper or coil though... Scott
bobmon@iuvax.cs.indiana.edu (RAMontante) (10/23/89)
->>}out. Generally speaking, RLL drives are intrinsically auto-park, - -> Fact is, I can't think of any RLL drives that use stepper motors. ->Might be a handful out there. Anyone know for sure??? Maybe some ->of the early ones??? scott@csusac.UUCP (Skitzer) <1989Oct23.012059.15012@csusac.csus.edu> : -My Seagate ST-238 RLL isn't autoparking...Don't know if it's stepper or -coil though... ST-238's (which are sort-of ST-225's, sort-of upgraded for RLL) use a stepper motor. I believe the more recent units will auto-park, but the early ones didn't. (In fact, the early ones still don't, without help :-) I wouldn't be surprised if most drives, RLL or not, auto-park these days. It's just a good idea that finally came around.
Ralf.Brown@B.GP.CS.CMU.EDU (10/23/89)
In article <4274@ncsuvx.ncsu.edu>, unkydave@shumv1.uucp (David Bank) wrote: > Fact is, I can't think of any RLL drives that use stepper motors. >Might be a handful out there. Anyone know for sure??? Maybe some >of the early ones??? Try the ST238R and ST277R.... -- UUCP: {ucbvax,harvard}!cs.cmu.edu!ralf -=-=-=-=- Voice: (412) 268-3053 (school) ARPA: ralf@cs.cmu.edu BIT: ralf%cs.cmu.edu@CMUCCVMA FIDO: Ralf Brown 1:129/46 FAX: available on request Disclaimer? I claimed something? "How to Prove It" by Dana Angluin 6. proof by omission: "The reader may easily supply the details." "The other 253 cases are analogous."
karl@ddsw1.MCS.COM (Karl Denninger) (10/25/89)
>----- >Response 2 of 2 (6247) by ralf at b.gp.cs.cmu.edu on Tue 24 Oct 89 17:24 >[Ralf Brown] >(13 lines) > >In article <4267@ncsuvx.ncsu.edu> unkydave@shumv1.ncsu.edu (David Bank) >writes: >}depends on the hard disk. Check with the manufacturer to find >}out. Generally speaking, RLL drives are intrinsically auto-park, >}while most MFM drives are not. > >My MFM ST4051 is most definitely autopark. I think the deciding factor is >whether the head positioner is a stepper motor (nonparking) or voice coil >(autoparking). Not true. The difference is whether the maker decided to make the drive autopark, and has little relevance other than that. Seagate drives 40MB and up (251, 277R, etc) all autopark. 4038's autopark. MOST smaller drives do NOT autopark (238, 225, etc). I have never seen a voice-coil positioner that did not autopark, so you can use that as a guide. It is not a tell-all, however, as the 251/277R series of Seagates is definately a stepper device, and it DOES park the heads when the power is turned off. -- Karl Denninger (karl@ddsw1.MCS.COM, <well-connected>!ddsw1!karl) Public Access Data Line: [+1 312 566-8911], Voice: [+1 312 566-8910] Macro Computer Solutions, Inc. "Quality Solutions at a Fair Price"
wek@point.UUCP (Bill Kuykendall) (10/26/89)
>(2) My understanding is that frequent power cycling (i.e. shutting off > the PC/AT whenever it's not in use) cannot cause damage to or > in any other way hasten the wearing out of any part of the PC. > Is this really true? Or is it better for the machine to leave > it running 24 hours a day as much as possible? Leave it running. The hard disk is essentially an electric motor with a set of flywheels attached to (mechanically). During powerup acceleration there is thrust on the spindle that wears the thrust washers and eventually allows the platters to contact the heads. There is also a spindle brake which activates when you shut the drive down that can get stuck when the bushing in the actuating solenoid wears (the brake spindle cocks in the bushing, causing it to bind). There are dozens of reports populating the net about drives that need to be manually nudged or allowed to sit with the power on for awhile before they'll spin up. This is the cause. Power your monitor off though (unless it's a Monoterm!) so that the screen doesn't get burnt in. >(3) I've gotten conflicting information on the necessity of manually parking > the hard disk heads before powering down the machine. Some Others have said it -- it depends on the drive. You'll have to ask the manufacturer. --------------- Bill Kuykendall Chicago, IL USA ...!point!wek wek@point.UUCP
Howard.Spindel@p8.f14.n105.z1.FIDONET.ORG (Howard Spindel) (10/26/89)
> In an article ralf@b.gp.cs.cmu.edu (Ralf Brown) writes: > > My MFM ST4051 is most definitely autopark. I think the > deciding factor is > whether the head positioner is a stepper motor (nonparking) > or voice coil > (autoparking). Well, my ST251-1 is autopark and it's a stepper motor. My Maxtor 2190 is autopark and it's a voice coil. So it doesn't look like that's the deciding factor. I think the deciding factor is whether or not the manufacturer decided to make it auto parking. Eschew Sesquipedalian Obfuscation! Usenet: Howard.Spindel@p8.f14.n105.z1.FIDONET.ORG Fidonet: 1:105/14.8 -- Howard Spindel - via FidoNet node 1:105/14 UUCP: ...!{uunet!oresoft, tektronix!reed}!busker!14.8!Howard.Spindel ARPA: Howard.Spindel@p8.f14.n105.z1.FIDONET.ORG
olaf@cbnewsc.ATT.COM (olaf.henjum) (10/28/89)
WOW! As the poster of the message that seems to have started this long discussion on hard disks, I'm impressed. So are the other PC-beginners I was trying to get some advice from before posting that query to the net. Since the best/most-consistent answers to the questions of (a) how to tell if a HD auto-parks, and (b) what effect if any power cycling has on an AT's innards seem to have already been copied to the net, it once again seems unnecessary for me to post a summary here. I've gotten several interesting recommendations for various PC implementations of COBOL (my third question), and will be posting a summary of that e-mail as soon as I'm reasonably sure all of the responses are in. Again, thanks very much to all of you out there in net-land who actually wade through this newsgroup and offer meaningful advice to the beginner! -- Olaf Henjum (att!ihlpf!olaf)