uhclem@trsvax.UUCP (10/16/89)
<> B>I am considering upgrading the 15 Meg hard disk on my Tandy 6000. The current B>one is functioning fine, but is getting a bit full. B>I hear that the interface is a ST506 so any PC drive should work. Almost any. B>Are there any size or number of head restrictions? Unless you are willing to make mods, restrict yourself to 8 heads by 1024 cylinders. If you are willing to replace the 1010 controller with a 2010, you may go up to 8 heads by 2048. (A two byte patch is also needed.) B>Should I expect any remarkable speed increase? Unless you buy a really slow drive (and getting one slower than the 15 Meg you have is almost impossible), you will see a speed improvement. I would replace the 15 Meg entirely or make it the secondary so that the root partition is on the newer and hopefully faster drive. Of course, any XENIX/UNIX system sees better performance on a freshly-installed filesystem. B>Do you just buy a standard PC drive, If it meets the above requirements. You may need to tape pin 2 on the "Control" cable (that's the 34 pin cable to the drive), so that if you really bought a ST-412-compatible drive (most MFM drives today are really 412s, not 506s), it won't get upset. I bought a ST4096, which has nine heads and am simply not using head 9 since it was cheaper than an eight-head drive with the same number of cylinders. B>put it in an expansion chasis, and plug it in the back B>of the computer using the standard cables supplied with the drive? Don't forget a power source for that drive. The power for external drives does not come from the CPU enclosure. If you have a built-in hard disk now, the controller limits you to a total of two drives. B>Also, for referrence, does anyone know the access time and data transfer B>rate for the standard 15 Meg drive. For reference, all ST506/ST412-compatible drives have a 5.0 Mbit/sec transfer rate to and from the controller. The controller has a byte available typically every 16 usec. The Tandon TM503 15 Meg hard drive (what Radio Shack used in everything that used a 15 Meg drive), has an average seek time of 85 msec, 170 msec max seek, track to track of 18 msec and latency of 8.333 msec. The average access time is avg seek+latency, or 93.333 msec. Estimated MTBF, 11,000 hours. By comparison, the Seagate ST251 (slow version) 40 Meg drive has these specs: 40 msec avg seek, 95 msec max seek, 6 msec trk to trk, 8.333 msec latency, or 48.3333 avg access time. The faster version, the ST251-1 provides: 28 msec avg seek, 70 msec max seek, 6 msec trk to trk, 8.333 msec latency, or 36.3333 avg access time. Both have estimated MTBFs of 50,000+ hours. ST412 drives with avg seek speeds in the upper teens are also available. <This information is provided by an individual and is not nor should be construed as being provided by Radio Shack or Tandy Corp. Radio Shack/Tandy Corp has no obligation to support the information provided in any way.> "Thank you, Uh Clem." Frank Durda IV @ <trsvax!uhclem> ...decvax!microsoft!trsvax!uhclem ...hal6000!trsvax!uhclem Like their old ad said: "Tandon. The last place you would ever go to buy a disk drive." THE HEADLINE IN THE AD REALLY SAID THAT.
uhclem@trsvax.UUCP (10/17/89)
typically every 16 usec. The Tandon TM503 15 Meg hard drive (what ^^^^^^^ Make that 1.6 usec. Dropped a period somewhere.