115
votes
Accepted
Why did the Apple IIe make a hideous noise if you inserted the disk upside down?
While some floppy drives have a sensor to determine when the head is at the outermost position, the Apple uses four approaches:
On startup, it blindly tries to move the head outward about 40 tracks. ...
- 28.1k
39
votes
Accepted
When did 5.25″ floppies exceed the capacity of 8″?
In practice, 5.25" drives equalled or exceeded the capacity of 8"
drives when 5.25" floppy drives started using HD media.
The Evolution of 5.25" Drive Systems
There are only two ...
- 21.9k
34
votes
Accepted
Why are the magnetic floppy disk drives (FDD) heads not frictionless?
TL;DR:
"Frictionless" Floppies are called Hard Disks (*1), consisting of a hard media platter and a head in distance of the media (flying or otherwise)
Floppies are 2D tapes. While slower ...
- 173k
26
votes
Accepted
Could you manually eject a floppy quick enough to prevent data loss?
I did that all the time on the Apple II. The reason it worked was that some time was needed for the motor to spin up to the correct speed, and that the Disk II didn't really have an "eject" mechanism, ...
- 21.9k
24
votes
Accepted
How does a floppy drive identify the first and last sectors and tracks?
The track identification part is quite simple. Floppy formats are standardized so that there are specifications what is the distance between tracks (e.g. 96 tracks per inch) and what is the position ...
- 17.9k
23
votes
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Absolute maximum number of nibbles on an Apple II floppy disk track?
The maximum is 8309 ($2075) nibbles for track 0. Well, according to a little experiment I did. ; - )
The Disk II uses Constant Angular Velocity standardized by Shugart at 300 RPM. The earlier 8-inch ...
- 6,853
19
votes
Accepted
Is there any way today to recover/dump 2M disks?
In my experience, your best bet to read 2M/2MGUI disks is to find an old PC with a built-in floppy controller, and run either DOS (with 2M and 2MGUI) or Linux (with Mtools, which supports 2M formats) ...
- 96.6k
19
votes
Accepted
Can I use all features of a Commodore 1571 external drive from a C64?
Mode Selection and Switching
By default a 1571 always boots up in 1541-mode
when detecting the first burst (C128) transfer it switches automatic into 1571-mode.
OPEN 1,8,15,"U0>M1":CLOSE ...
- 173k
19
votes
Accepted
Why did Atari floppies run at 288 RPM?
the 810 and 1050 specifically, ran at 288 RPM rather than 300. I can't imagine why this might be,
I do believe it was needed to securely store 18 sectors per track while using the WDC1771 at 1 MHz ...
- 173k
17
votes
Did any laptop computers have a built-in 5¼-inch floppy drive?
The closest thing to a modern laptop that I'm aware of featuring an internal 5 1/4 drive is the Findex of 1979 which had a fairly complete (optionally battery-powered) CP/M computer including a hard-...
- 28.4k
17
votes
Accepted
DOSBox problem reading floppy boot sector using INT 0x13 on a drive mounted using MOUNT
DOSBox only allows absolute sector reads from disk images, as mounted by IMGMOUNT.
You can’t use interrupt 0x13, service 0x02 on drives mounted with MOUNT. (To understand that link, note that ...
- 96.6k
17
votes
Can powering on/off a 1541 damage a disk left inside?
According to the 1541 service manual, the device contains power-up and power-down write protection. On power-up, the CPU controls the power to read/write electronics so they are not turned on before ...
- 17.9k
16
votes
Could you manually eject a floppy quick enough to prevent data loss?
Theoretically, yes.
The disk needs time to spin up to speed before reading or writing can occur. While it varies between platforms and drives, it's at least a couple hundred milliseconds. That's ...
- 9,956
16
votes
Can special tools recover data from floppy disks when Windows Explorer fails to do so?
It sounds like some blocks on the disk (particularly the ones containing directory information) are okay, but some (containing some file data) are not. This is a data recovery situation.
If you boot ...
- 16.1k
15
votes
Did any laptop computers have a built-in 5¼-inch floppy drive?
If the definition sought after is very strictly speaking "integrated 5.25 inch floppy" and "battery powered", then I would like to enter the Kaypro II from August 1982:
Which is a ...
- 1,247
15
votes
Accepted
Did any laptop computers have a built-in 5¼-inch floppy drive?
As so often this depends on your definition of laptop - which is not an exact one either. There where many level of size and weight between a bulky schleppable like a Compaq Portable and a notebook ...
- 173k
15
votes
Why did the Sharp X68000 use 5.25" drives?
Why did Sharp choose 5.25" over 3.5"?
Why something has 'not' been done will seldom get an easy answer. Often it might be a variation of 'why should they'.
When the X68000 was released in ...
- 173k
13
votes
Accepted
How does a HD floppy drive react to an ED disk?
It doesn’t, at least not in any particularly useful way. Because of the position of the density sensor cut-out on ED floppy disks, they’re detected as 720K floppies by HD drives. Their contents can’t ...
- 96.6k
13
votes
Accepted
Were single-sided floppy drives really more tolerant of rough handling?
In a double-sided drive, there are two heads which are necessarily closely spaced, facing both sides of the thin magnetic-coated disc once it is inserted. The concern would have been that the heads ...
- 16.1k
13
votes
Accepted
How are blocks stacked on a floppy or older HD
A sector is the minimum amount of data you can read from a floppy disk or harddisk. As you've drawn correctly, a sector is part of a track (on a harddisk also called cylinder, because there are many ...
- 21.9k
13
votes
Accepted
Connecting old Floppy Drive to modern computer
There are a number of devices which can be used to connect a floppy drive to a modern computer. Whether they are appropriate in your case depends on what you’re trying to do...
If you want to read and ...
- 96.6k
12
votes
Accepted
How can the number of cylinders be different from the number of tracks?
As far as I can tell, the first edition of the IBM 5150 Technical Reference is the only IBM manual which mentions 45 cylinders. Few Technical References document the FDC, which is where the “45 ...
- 96.6k
12
votes
I can't read DS 1MB floppy disks
Many USB floppy drives will not read double-density (720 / 800 KB) disks at all. Most that can will only read 720 KB disks formatted for IBM PCs.
I am not aware of any standard USB 3.5" drives ...
- 9,956
12
votes
Accepted
How was end-of-file stored on a Commodore 1541 disk?
Excerpted from Inside Commodore DOS, page 53
4.6 Sequential File Storage
The format of a sequential file is very straightforward. All the sectors, except the last one, look like this:
TRACK LINK -...
- 8,456
12
votes
Can powering on/off a 1541 damage a disk left inside?
I don't know about the 1541 in particular, but I have personally lost data by powering off a computer with a diskette in the drive. One problem that could occur, independently of whether you ...
- 1,844
12
votes
Accepted
Is there a way to trick my 386SX laptop into thinking there's a floppy drive installed?
The standard algorithm to probe for floppy drives (and tell 1.2MB drives from 360KB drives) is patented by IBM and yet cloned by most BIOS manufacturers. There were litigation lawsuits against Award ...
- 6,171
11
votes
How does a HD floppy drive react to an ED disk?
It won't work reliably at all. The magnetic properties of ED media are very different from the magnetic properties of HD or DD media.
On both HD and DD media, the magnetization is "in-plane" ...
- 6,171
11
votes
Absolute maximum number of nibbles on an Apple II floppy disk track?
Apple ][ used an ordinary disk transport and fixed bit-rate in the controller.
In order to fit more bits on the outer track it would need to vary the spin rate of the disk so that the controller had ...
- 381
11
votes
Why did the Apple IIe make a hideous noise if you inserted the disk upside down?
The short answer is they did it to save money. They could have made the drive behave better when a disk is inserted upside down, but that would have required larger ROM chips to store the firmware or ...
- 14k
11
votes
Why did the Apple IIe make a hideous noise if you inserted the disk upside down?
The obvious answer is that it wasn't designed 'for newbs' but as a general purpose personal computer that would find its way into many homes and businesses as well as educational establishments. Even ...
- 1,469
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