105 votes
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On DOS computers, what would the PARK command do?

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 ...
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64 votes

Apocryphal (?) tale of hard drive platter propelled through a wall?

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 ...
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  • 6,385
49 votes
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Why were optical drives not used as secondary storage instead of magnetic drives?

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 ...
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47 votes

Why were floppy disks invented after hard disks?

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 ...
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44 votes
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Why was computer memory so expensive and scarce?

As noted in some initial comments (but I feel fine answering, as I had the exact same ideas when I read the question), this is a general progression of technology but there are two very specific ...
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37 votes
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Why do hard drives not use larger platter sizes anymore?

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-...
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37 votes
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Why were floppy disks invented after hard disks?

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 ...
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36 votes
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How much did the first hard drives for PCs cost?

I looked at trade periodicals from the time in question, because the intended customer for a hard drive in the early 1980's was almost certainly a business or school (look at the prices, particularly ...
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  • 1,851
33 votes

Is it possible to limit HDD capacity to work on an old computer?

Since the price seems to be an issue, I'll suggest a cheap alternative to hard drives. A IDE Compact Flash card reader with a 4GB or 8GB compact flash card is a cheap combo, still sold (less than 10 ...
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27 votes

Why was computer memory so expensive and scarce?

I'm mostly concerned about RAM. Why was it so expensive? It wasn't - at least not once integrated circuit RAM became available in the 1970s. Compared to other chips, RAM was cheaper both per ...
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26 votes
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How does Windows 9x determine which disk drivers correspond to which BIOS disks/DOS drive letters?

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 ...
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26 votes

Why were optical drives not used as secondary storage instead of magnetic drives?

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 ...
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  • 1,624
25 votes

What were the early PC applications requiring a hard disk?

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 ...
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  • 8,156
23 votes
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Apocryphal (?) tale of hard drive platter propelled through a wall?

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 ...
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21 votes
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Can a stock/original Atari ST boot from a hard drive?

All models of the Atari ST1 had code in ROM to attempt to read and run a boot sector from the first sector an ACSI2-attached drive. The bootloader3 contained in that sector would4 load the hard disk ...
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  • 8,930
19 votes
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What were the early PC applications requiring a hard disk?

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 ...
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  • 1,062
19 votes
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Default (as opposed to physical) read/write heads - what are they?

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 ...
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19 votes

How much did the first hard drives for PCs cost?

TL;DR: How much did the first hard drives for the IBM PC or Apple || cost, and how big were they? Ready to use setups started around 3,000+ USD for 5 MiB in 1981 Long (Hi-)Story As usual defining '...
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18 votes
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How can I take an image of a 50-pin SCSI hard-drive

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, ...
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18 votes
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Getting data from Seagate ST-238R drive

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 ...
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  • 1,455
17 votes

Is it possible to limit HDD capacity to work on an old computer?

I have not tried it, but according to the Wikipedia page on the Host Protected Area, one use case was to use large disks on systems whose BIOS could not cope with them. It would therefore seem to be a ...
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15 votes
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Hard coded hard drive BIOS geometries

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 ...
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15 votes

Apocryphal (?) tale of hard drive platter propelled through a wall?

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 ...
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15 votes
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How Amiga A590 autoboot ROM and bootable floppy disk works?

In order to autoboot any Amiga hard disk, 3 things are needed. A version of Kickstart that supports boot from HD. This means >= Kickstart 1.3. A device driver that knows how to speak to the HD ...
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15 votes
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Was there ever a Linux kernel driver for accessing disks via BIOS?

To my knowledge, no such driver has ever been written. Since the very earliest versions, Linux has been a pure 32-bit protected-mode kernel that drove most devices (including disk controllers) ...
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  • 17.1k
15 votes

Why was computer memory so expensive and scarce?

Didn't people living at that time feel sudden reductions in size/availability as technologies evolved? And if they didn't, why wasn't there a "jump" in memory availability when technology ...
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  • 965
14 votes

How can I access an old pre-IDE disk?

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'...
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  • 4,052
14 votes

What were the early PC applications requiring a hard disk?

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 ...
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