95

Hard drives have read/write heads which fly above the spinning disks when the drive is powered. When power is removed, the heads no longer fly... For a long time now, the arms which hold the heads have been designed to “auto-park” the heads away from the disks’ surface, or over a safe “landing zone”, when they lose power¹, but early (up to the mid 80s) hard ...


64

Some "informed speculation" based on my "day job" which involves worrying about containment of rotating objects if they break (specifically, rotating parts inside jet engines) The rotating parts of early disk drives were substantial objects. For example the IBM 350 had 24 inch diameter platters rotating at 1500 RPM, with a rotating mass of about 10 pounds. ...


49

For the simple reason that until relatively recently, it was very difficult to make a rewritable optical medium, but it was easy to make a rewritable magnetic medium. Magnetic tape as a recording medium has been a practical technology since the late 1930s, predating the digital computer. For comparison, CD-RW was introduced only in 1997, more than a decade ...


47

Floppy disks are harder to get right than hard disks. Early hard disks were enormous; the IBM 350 used fifty 24-inch platters. They were also rather fragile and cumbersome (heavy and power-hungry). To go from a hard disk of this sort to floppy disks required a number of developments: in particular the ability to remove the platters (which came in 1962 with ...


37

While Stephen Kitt's answer already hits the core, I believe it needs a bit more history, as direct access magnetic storage did start quite a while before the IBM 350. Drums and Disks First there were drums. Drums were huge cylinders with a magnetic surface, and a separate head for each track - something that would have been rather impossible with a disk. ...


36

My question is if you can fit X number of tracks on a 3.5" platter, why not use the same density on a 5 1/4 platter and have even more tracks? I know there are tradeoffs like latency due to head-travel or cost / complexity if you tried to put multiple heads on the same platter-side but in any case you end up with a capacity that is unobtainable with the ...


26

Write speed and endurance. Optical drive technology has been much slower to write to than magnetic Hard Disk Drives (HDDs). The erasable optical technologies that made it to mass market were much slower in write time than HDDs and in erase time. Their life before failure was in the 100's of erases. Optical drive use declined with the advent of USB flash ...


25

By their contents. When Windows boots, the I/O Supervisor VxD (IOS) uses BIOS interrupt 0x13 services to read sector 0 (the Master Boot Record) of each drive. It then looks at two bytes at offset 0x0DA. If they are zeroes, IOS checks the following four bytes: if they are also zeroes (like in the standard MBR code written by Microsoft’s FDISK), IOS overwrites ...


23

There is also this tale that I read recounted in Philip and Alex's Guide to Web Publishing, although the disk pack was intentionally hurled through the wall in a fit of temper: That night, the Foonly crashed. A Foonly was a clone of the PDP-10, a mainframe computer designed by Digital in the 1960s. MIT and Stanford people loved the PDP-10 but couldn't ...


21

I cannot state for certain that it required a hard disk, but using AutoCAD (v1 released Dec.82) without one would have been awkward to well-nigh unbearable. The program itself was huge for the time and used countless data files. I can't imagine running it from floppy. Even if v1.0 could do so, by the time v2 or v3 was released HD had to be required. It ...


18

If "a more modern machine" includes systems with ISA, PCI or PCI Express slots, it should be easy enough to retrieve the data from the drives. You'll need a SCSI adapter (known as a host bus adapter, HBA); you can find loads on auction sites, or SCSI4ME and other places (depending on which country you live in). Adaptec cards are very good and well-supported ...


18

The ST-238R shown in the image is an RLL (Run Length Limited) drive and will not work correctly with a standard MFM controller, although it has the same ST506 electrical interface and cabling. To read back your data, you will need an RLL controller, which unfortunately are less common than MFM controllers and might not be easy to find. RLL is an encoding ...


17

The physical geometry how many heads the drive actually has is not the same as the logical geometry of how many heads is presented to the PC by the drive. By translating the geometry, the drive can be fully addressable to up to the maximum of approximately 8 gigabytes in CHS mode, as the IDE interface is limited in CHS mode to 16 heads, 63 sectors and 16383 ...


16

I started working for a newly-certified IBM PC dealer in the UK at the end of 1984. IBM thought we would be selling about 50% twin-floppy PC (PCG) and 50% XT with 10MB hard drive. In fact, I'm not sure we ever sold a PCG. Perhaps it's because we were focused on accounting and payroll applications for small businesses - not something you would consider with ...


15

The tables were built using the parameters for various real hard drives. For example, type 1 is used for the original Shugart drives used in the PC XT (ST506). So the intention was for the drive types to be useful, and at least some of them were; in the linked page, scroll down to the list of Award-486 drive types to see more examples. Each BIOS ...


15

I've heard of disk heads being propelled at great velocity, though that may be just a scary story told to young people, too. This is the disc store from a 1965 KDF9: If a read/write head contacts the spinning disk, it could (I suppose) get ripped off the actuator arm, and thus be accelerated to the extent that it penetrates the glass on the door and causes ...


14

That Conner CP-343 drive appears to be a special snowflake, but it's not. It's actually a standard IDE drive, with one exception. That 20-pin interface you're looking at isn't the IDE connector; it's the connector between the drive mechanicals and the controller board that would normally be mounted to the bottom of the drive. Why it's not affixed to the ...


14

Yes, this is possible. The file utility can recognise many disk partition layouts and file systems. If you connect your drives to your Pentium III system, running a version of Linux, they should appear as /dev/sd? devices. To simplify further analysis, you should copy their contents to a file: sudo ddrescue /dev/sdX backup.img backup.map (replacing X as ...


13

This is a SCSI device, so it shouldn’t be too hard to get the data off the device. You need the following pieces of equipment: a SCSI controller, known as a host bus adapter (HBA); these are available for most buses, including USB (getting rare though), PCI and PCI Express (the last two are still easy enough to find, especially second-hand; expect to pay a ...


13

You’re running into compatibility issues with very old drives. In this particular case, your drives are new enough to support the ATA “identify device” command (which is how your hwinfo input includes the drive’s names), but there’s something going wrong with the “read capacity” commands. I suspect the reason is that these commands are LBA-based, and your ...


13

You seem to be proposing a custom HDD "driver" that would image the HDD block-by-block by sending those blocks across a serial port to some sort of process running on your modern computer that assembles the blocks into an image file. This could be error prone and time consuming to implement. An alternative suggestion is to use a legacy DOS Utility, such as ...


11

The easiest way is to get an external USB enclosure or USB-to-IDE adapter. IDE-to-SATA adapters exist, but they require opening up your computer to install. When selecting hardware, keep in mind that IDE (PATA) hard drives come in two common varieties: "desktop" (usually 3.5" form factor, with a 40-pin data cable and a 4-pin power cable), and "laptop" (...


11

The order of switching should be relatively arbitrary - After all, there were Ataris around (like the Falcon or ST/E) that didn't have a separate power switch for the hard disk and where it was relatively random what stopped first. But, if in doubt, ask the manual. The Atari Megafile manual says the following: (I'm especially fond of the "...when the ...


11

Larger radius = lower RPM, which makes pretty much all timing specs worse. The Quantum Bigfoot was limited to 3600 RPM. Why not spin faster, like a Cheetah X15 (15 kRPM)? Flutter and buffeting. Halving the radius gives four-times reduction in these effects (assuming no spindles -- real platters are on spindles and the coupling to these spindles provides ...


11

You can check the Whole Earth Software Catalog; I remember it listed a few apps as requiring hard disk. It came out in 1984, which would have been pretty early. For example DESQ does (pg 114). It's not a database btw, but a window switcher/proto-gui type of thing. Real World Accounting on pg. 103 is another, and there's even a program called Great Plains ...


11

Floppy disks solve a different problem from hard disks: They're cheap, and they're portable. A floppy disk (even an eight-inch floppy) slips into a brief case or a file folder in a way that reels of half-inch magtape and punched card decks just will not do; and if somebody asks you for a copy of that report you're working on, you can hand them a floppy disk ...


11

Bus: yes should negotiate. Device size: possibly okay. If your OS can issue (and your scsi controller supports) a read(16), then you'll get the full capacity. If it only supports read(10), then it'll look like a 2TB volume (assuming the drive is bigger!). I've heard of some random old controllers that didn't support read(16) and caused problems for big ...


10

In all the BIOS setups I was dealing with that have similarly 47 drives to chose from the first or the last one was editable directly in BIOS SETUP for manual settings. Sometimes the manual settings was done in different menu entry (near formatting utility ... but beware do not accidentally format IDE !!!). IIRC DOS uses BIOS routines for HDD access so if ...


10

This command is supposed to place HDD heads on "park" position.


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