44
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 ...
36
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. ...
19
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 drives were 360 RPM, and since the physical media was the same it's likely that 300 RPM was chosen to increase data density on the smaller disks, and perhaps ...
18
As far as I'm aware there is no source of new 8" drives.
If you do manage to find a working drive, there are a couple of options to connect it to a modern PC over USB:
the KryoFlux floppy controller, which has successfully been used to connect an 8" drive;
the DiscFerret, which is also supposed to support 8" drives, but is harder to find for purchase.
As ...
18
The sound came from the fact that drives would only report on the presence of a disk if the heads were moved. Thus by default, the OS would move the heads back and forth.
Alternatively, the heads could be moved fully to one side and then asked to step further to that side (by default the heads would be centered to minimise seek time or read the central ...
17
Hard sectored 8" and 5-1/4" floppy disks were used in some early computers including:
DEC Pro 350
Heath/Zenith H-89a
MITS Altair 8800BT
NorthStar Horizon
Vector Graphic computers
Processor Technology add-on for the Sol-20 computer called the Helios II Disk Memory System
Compudata Exidy Sorcerer add-on floppy drive based on the Micropolis
Quite some of the ...
16
It seems to me that since disk drives are fundamentally horizontal devices that want to be wide rather than tall,
To me they are taller than wide. After all, that's as well the orientation IBM did put the very first drive, so anything else is plain wrong, isn't it :))
the obvious solution would be to stack them vertically.
That's pure opinion and up to ...
15
Any real attempt to use the momentum of the spinning disk to generate power would cause the disk to come to a halt very quickly. In essence, this is the principle behing regenerative braking of electric vehicles. Otherwise, you would have a perpetual motion machine.
However, there certainly were computers that used the momentum of a disk that was spinning ...
12
In the first phase of the boot process, the BIOS loads the first sector of the disk into memory and executes it. The code in this sector then uses the BIOS to load the code for the second phase, which in turn use their own drivers to load and initialize the remaining OS.
The BIOS knows how to access the USB floppy drive. But when you try to boot an OS that ...
12
Yes; this was standard procedure for at least the BBC Micro:
Including for third-party drives:
Presumably because two drives arranged that way were only just taller than the machine itself:
11
Unfortunately, you can't connect two floppy drives to the motherboard header on that system. Like most motherboards since sometime around 2002–2003, it only supports one floppy drive, probably because its I/O is implemented using a low-pin-count SuperIO chip with too few pins to drive two floppy drives. The fact that your BIOS setup only mentions one floppy ...
11
There were a number of programs that used the 6502 in the 1541 as a coprocessor.
An obvious application was for calculating fractals, because that doesn't need a lot of RAM. An example is the Mandelbrot Construction Set (German article).
This thread also mentions some more recently written games which used the 1541 as coprocessor, namely The Masque, Panta ...
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 ...
10
That Conner CP-343 drive appears to be a special snowflake, but its not. Its actually a standard IDE drive, with one exception. That 20-pin interface you're looking at isn't the IDE connector, its the connector between the drive mechanicals and the controller board that would normally be mounted to the bottom of the drive. Why its not affixed to the ...
10
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 time to put the extra bits on.
CD drives use variable spin rate, but floppy disks (mostly) use a fixed spin rate (like gramophone records).
Early Apple ...
10
Leave it empty. In floppy drives, the read/write head touches the disk’s surface, so leaving a disk inserted for long periods of time can cause problems — the head will tend to stick to the surface, pulling it off when the drive is next powered up.
Some drives shipped with a cardboard insert which was intended for use in shipping and long-term storage, but ...
10
How exactly does one send a new routine to the drive and execute it?
Usually by executing the Memory-Write command twice followed by UserN command, as described in chapter 8 of the floppy manual (*1)?
Once to place the routine to be used and then to setup its address as user function (or whatever it is supposed to replace).
A suitable function to do so ...
9
The PDP-11 had a 'power fail' trap that would be invoked when a problem with AC power was detected by the power supply. The system then had 2ms of runtime (powered by capacitors in the power supply, not disk momentum) to save volatile data. Typically, this was limited to the contents of the CPU registers (including the program counter and stack pointer) ...
8
Since at least Kickstart 2.0, the OS has built-in code that allows for drive checking without making the click noise. To enable it, just set the TDPB_NOCLICK flag in the tdu_PubFlags of trackdisk.device's unit structure (of type struct TDU_PublicUnit) for the drive you want to silence.
Don't know about earlier. I guess trackdisk.device was patched with ...
8
Any electrical motor can, with the right driver circuit, act as a generator.
The easiest case which does not need any outer circuit at all (it's all built in) is a shunted DC motor, it acts as a voltage source as long it is rotating. That one is called Counter-Electromotive Force. How many volts depends on the motor characteristic and the speed. When the ...
8
Yes, the mechanical mechanism was patented. I can't find any evidence for a software patent.
It looks to be US patent 4466033 which was originally developed for the Lisa's Twiggy drive but adapted for use in the original Mac drive. Here is a quote from the second link:
The Sony 3.5” micro-floppy was uniquely enhanced for the Macintosh by
incorporating ...
8
Playing music with the drive heads, of course. I've tried that too, wrecking the drive in the process.
Dimming the drive LED, by flashing it very fast, with a variable duty cycle.
Printing a file on disk directly to a daisy-chained printer, freeing up the computer to do something else.
Direct disk-to disk copy between two 1541 units, similarly to the one ...
7
On modern motherboards, the floppy is controlled by the Super I/O chip, and often this chip is only capable of controlling one floppy drive, because the additional drive select/moter pins are not present by design.
I have a similar problem: My motherboard has a Nuvoton NCT6776F Super I/O chip, and that can work with one floppy only.
I am thinking of ...
7
Normally Commodore drives are device numbers 8, 9, 10, and 11, and drives 0 and 1, giving 8 drives, but some newer products support device numbers up to 31 (although 31 is reserved for UNTALK/UNLISTEN command), giving 23 devices with two drives each for a theoretical total of 46 drives.
Unfortunately, the 7406 chip on the IEC bus can only handle 40 mA of ...
7
The loading code does it; you can see that the CPU writes to one of the audio registers during the load if you disassemble the ROM. The "feature" could be disabled through code although it was usually reassuring during tape load.
As far as tapes go, the program was stored on one track and the second track was free for audio; I have only seen this feature ...
7
Reposting slightly, but this (German-language) page provides software for networking C64s via the serial bus, with the simplest intended power-on state being two C64s connected to the two inputs of a 1541, having one set to ignore the drive while the other loads, then reversing that, then having them talk to each other and to the drive through negotiation.
...
6
Nibblers that are utilizing opencbm on a PC need a faster-than-stock connection to read the GCR encoding in real time. There are a couple of solutions, the most common of which requires a ZoomFloppy. To nibble from a 1541 requires a parallel port. 1571 drives are much faster due to better hardware, allowing ZoonFloppy to nibble over serial.
6
From a quick search, it sounds like the quickest way to solve it is to update the 1581's ROM (see this thread on Lemon64) - either by buying JiffyDOS, or finding the newer version of Commodore's own firmware (such as from this page).
Only top voted, non community-wiki answers of a minimum length are eligible
