Tom's Guide | Tom's Hardware | Tom's Games
 |
 |
 |
I changed a HD and it reads- Precomp
OFF -220mg that started out as a 540mg I'm just wondering if it's going to give me a problem down the road when it comes to running setup I hope not because I don't want to revert back to the old 40mg Open for comments.............
WPC = Write PreCompensate
Just like on an old vinyl record, as the needle gets closer to the center of the disk, it tends to move faster - same thing on early HDDs - they had to compensate for speed variations as the write heads worked closer to the center of the disk platters. On a modern disk the setting is usually 'off' (sometimes '65535' means the same thing). If it's an older drive, check its specs - can make a difference.
Dan Penny (another contributer) posted a great article on this a few weeks back... somewhere on these boards.
If the drive geometry isn't listed on the actual hard drive, then you may need to look it up to get the correct values for WPC, cylinders, heads & sectors.
Later versions of CMOS would allow you to enter pretty much any value necessary under a 'user defined' setting - but I'm not so sure you could do that on a 286 - on those the CMOS drive table is just that - a list where you try to match up your disk with the closest settings there.
If you're not sure of your HDD's settings, you could post the make & model # here, should be able to figure it out.
0 
Gee that sounds interesting Jboy maybe someone will read this and send that article to me to me .. I don't know if I have to or not but I'll do it anyway (LCHARTRAND@COGECO>>CA) yes I'm up here in Canada Ont. I see other people leaving their email ad but anyway you helped me again and about that HD being old I think it was manufactured around 95 and the old one I swapped this one with dos'nt look that old either but that's just a visal guess ! but I got that one sitting right here in front of me the other ones installed and it's quite a job removing that one I almost had to use a crowbar to get it to fit not that it was different just a tight fit if you know what I mean..... Thanks much appreciated........ AL
0
Heh - we live in the same province :)
Yeah, the drive very likely doesn't require WPC.
286's didn't have 'autodetect hard drive' feature in the CMOS, so it seems to me that if it set up on it's own, you got lucky. Still, if you can post the maufacturer of the drive and it's model number, might be able to set it up better on your machine - or might not, options can be limited on the old machines.
Your email address is linked to your name on the post ;)
0
Yes Jboy that word (options) was the word I was thinking of but could'nt at the time I was printing up these questions yes you got that right cause I changed a HHD in my first Pentium and I had to take that one to the shop to get it installed and I only had what they called a Big Foot it's size was the same as a Cd Rom and they installed it under the Cd Rom and it was only an 8gig and that cost me if you know what I mean after that I learned how easy it was to just go into the Cmos and put in my own ..On this one I'm using I installed a regular 10gig with Win 98SE and it is plenty for what I use it for although I use the scanner alot and it does use a lot HHD free space but I'll never fill it to compacity ..Anyhow I'll sign off now and once again Thanks for al the information much appreciated...... AL
0
Pasted in from;
http://www.computing.net/dos/wwwboard/forum/11099.html
Name: Dan Penny
Date: August 07, 2002 at 12:20:11 Pacific
Subject: Write Pre-compensation
Reply:
Precompensation is used with some hard disks to compensate for the higher recording density in the inner tracks during write.
Normally, precompensation and reduced write current begin approximately at half the cylinder count. The precompensation logic shifts certain bit patterns by +/- 12-15ns.Precompensation only affects writing, not reading of data.
Many hard drives work perfectly with or without precompensation, newer hard disks ignore the setting.
0
You learn something new everyday ...Well written well explained ..could'nt ask for any better explaination ....much appreciated.........AL
0
I would explain it differently. The face of each platter is divided into sectors and tracks. If it were drawn out on a piece of paper it could be seen that the innermost sectors are smaller than their counterparts at the outer edge of the platter. The number of bytes that a track can hold is determined by the centermost track, which meant there was a lot of wasted space on the outermost tracks. It was important that every sector on the drive have a consistant 512bytes.
Write precompensation speeds up the writing of data to the drive as the tracks become smaller near the center of the platters, thus insuring that each sector contains 512 bytes.
There was also something called Reduced Write Current, which was less common, but could reduce the current used to place magnetized spots on the disk. I believe this was done to prevent adjacent bits from affecting one another as they were now physically closer together.
Those older drive technologies include MFM, RLL, and ESDI.
With the newer drive technologies like IDE, something called Zone Bit Recording may be used. Here, you can have fewer sectors per track near the center of the platter than you do at outer edge, but each sector still contains 512 bytes.
Because of the way an IDE device is formatted, you have to use a controller specific to each drive, which might explain why said controllers are now mounted on the hard drive itself, rather than using an adapter card.
0  |
 |
 |
This post is quite old and has been locked from receiving new replies. Please create a new posting instead.
| Ads by Google |
