Vintage Seagate ST-157R-1 49MB RLL hard drive.
This is the FAST version (identified by the "-1" in the model number).
28ms, 3600rpm, 7.5Mbps xfer rate
CHS: 615/6/26
Write PreComp = none
Landing Zone = none (auto park)
Early, Classic Seagate hard drive.
Suitable for a collection or period-accurate early 90's retro system.
SN: 10985399

• Originally purchased directly from Seagate distribution in 1990 for our PC production.
• Was removed by our service dept decades ago during a routine upgrade and has been in protected storage since.
• These drives have had relatively little use — we had an aggressive upgrade program so most drives were upgraded after only 12 to 24 months. The removed drives have been stored undisturbed for decades.
• Full true low-level format performed, both to remove customer data, and also to refresh the format as is needed for early ST506/ST512 drives.
• Factory bad sector map entries were entered and locked out during low level format.
• Single large partition created.
• MS-DOS 6.22 freshly installed.
• Scandisk full surface scan shows zero bad clusters (see screenshot).
• Chkdsk shows zero bad sectors (see screenshot).
• Low-level format was performed using an OMTI-8247 RLL controller.
  • If you have exactly this same controller (or OMTI 8257), should boot right up (please see discussion below).
  • We have this exact controller available for purchase (see our listings).
  • To boot, BIOS drive parameters must be set as configured — CHS: 615/6/26.
  • With a different controller, you're on your own... will need a new low-level format and re-testing, but you know that this drive is intrinsically good.
  • NOTE: If requested at time of purchase, and at no extra charge, we will perform a low-level format using a controller you specify (we have most models, please inquire), and install MS-DOS 6.22 to save you this trouble (low-level formatting can be tricky).
• Note: this drive might have a stiction issue, which afflicted early hard drives. Stiction is the attraction of two surfaces at the molecular level causing the heads to stick to the platter surface, especially if sitting unused for a while, and the spindle motor may not have enough torque to break the stiction. I will include a paper with details of how to break the stiction if this happens.
• Clean, very good physical and cosmetic condition.

You will receive exactly the item you see in the photos.

Shipped via USPS with full tracking from a USPS regional SCF (Sectional Center Facility) so delivery anywhere within the U.S. is only a few days away (excluding the occasional USPS misdirect).

RETURNS:
• Sold with 30 Day Warranty — If the drive fails or a serious defect not described in the listing is found within 30 days of purchase, I will stand behind the product.
• Please contact me with details of any issue so we can resolve the problem or work out an appropriate solution.
• I will provide a reasonable amount of technical assistance if you have questions concerning the configuration or proper use of the item.
• Buyer's remorse returns must be in original condition, in original packaging, and may be subject to a deduction to cover the cost of retesting.
• Generally, the original shipping cost is not refundable.

Discussion:
• The earliest hard drives required a true controller. These early controllers actually 'controlled' the heads on the hard drive, positioning the heads to the correct track and activating the correct head to read the requested data. In the low-level formatting process, the controller lays down the tracks and sector marks. Different controllers do this slightly differently so that one controller probably cannot read the tracks written by a different model controller. It's safe to assume that if you change the controller model, you will need to perform a new low-level format with the different controller.
• One benefit of RLL over MFM not often considered is that not only do you get 50% greater capacity on the same media, but the resulting data transfer rate is also 50% faster! This is so because 50% more data is read and transferred within the same time.
• To clear up another point of confusion: The first controllers were MFM, then newer RLL encoding technology achieved 50% greater capacity on the same media. MFM controllers work fine with RLL drives, but with 1/3 lower capacity. RLL controllers 'probably' work with drives designed for MFM and increase the capacity by 50%. The magnetic recording is the same, but RLL utilizes a more efficient encoding scheme to pack 50% more data on the same track. MFM controllers always use MFM encoding, and RLL controller always use RLL encoding because the encoding schemes are hard-coded into the controller circuitry, therefore MFM and RLL controllers are not interchangeable (an MFM controller cannot function as an RLL controller, and vice versa). Keep in mind that changing the controller requires a new low-level format.
• Most people are familiar with IDE, which is an improved design — IDE (Integrated Device Electronics), as its name says, integrates the controller within the circuitry of the hard drive itself so it remains integral to the drive. IDE 'controllers' are not true controllers, but are simple adapters which connect the controller embedded in the IDE drive to the computer bus. The IDE interface is a defined standard, so IDE drives and adapters are freely interchangeable. Most IDE drive use RLL encoding and utilize zone-bit encoding to further increase capacity by varying the number of sectors on the outer vs inner tracks.