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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. ...
25
Amiga 500 1.3 machine only boots on drive 0 (DF0:) by default.
There are programs that make it able to boot on DF1: but they're not really interesting because a lot of games either:
have physical copy protection (even cracked copies can have some bits remaining and demand a disk in drive 0)
have non-OS compliant track loader which only searches the disk in ...
24
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 ...
21
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 ...
19
Functionally there is no difference between the VIC-1541 and 1541. Internally, there may be lots of differences due to production variation and component variation. The thing to remember is that both drives have modes to directly support the VIC-20 and C64. The VIC-20 is actually faster reading data when the drive is in 1540 mode instead of 1541 mode, but ...
19
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 ...
19
TL;DR:
The computer, or rather its OS, has no idea about a directory, in fact not even what constructs a file. It can only open/read/write/close data streams from devices on the bus. Getting a directory is a clever hack of 'loading' a dummy program. This works since
LOAD command is implemented as opening a data stream and loading what is returned into ...
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 ...
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 ...
17
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:
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the drive could end up only being able to transfer one bit per horizontal blank = 63 microseconds. 1/(63e-6) = 15873 bits/s = 1984 bytes/s.
That would be the bitrate during transmission within a byte, but bytes are framed and handshaked, which adds an average of 160 µs per byte. Resulting in (63 * 8) + 160 µs, or ~664 µs per byte. So the upper transfer sped ...
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 ...
14
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 ...
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
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 ...
14
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 ...
13
The beep comes from the OS ROM, and it is actually derived from the timing of the start and stop bits of each byte shifted into POKEY, this is determined from the interaction of the interrupts generated. The frequency output is nominally half of the operating bit rate, e.g. approximately 960Hz for a 19200 baud transmission (e.g. from a disk drive at normal ...
13
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 ...
12
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 ...
answered Sep 12 '17 at 9:07
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And now this: disk drive outputs the video signal through the serial bus connector!
"Freespin" Demo by Matthias Kramm (Quiss/Reflex):
https://www.youtube.com/watch?v=zprSxCMlECA
Technical details are described on the author's website:
http://www.quiss.org/freespin/
Every single raster line, we have generate sync pulse by pulling both
DATA and CLK ...
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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 may ...
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Without any modification Commodore 64 Serial Bus operates at 3200 bit/s (*1).
Effective maximum speed for C64+1541 is about 400 bytes/s.
Sustained speed with turn around and alike is about 300 bytes/s.
I am developing some software for the Commodore 64, and my intention is to use the 1541 as a coprocessor. I'll have the 1541 compute some data for me, ...
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You can get a relative ordering by looking at DOS versions for the drives.
IEEE-488 drives
2040 - first drive, 5.25"x2@170K, 1979, DOS 1.0
3040 - 5.25"x2@170k in Europe, 1979, DOS 1.2
4040 - 5.25"x2@170k, 1980, DOS 2.0
2031 - 5.25"x1@170k, 1980, DOS 2.0
4031 - 5.25"x2@170k, 1980, DOS 2.0
8050 - 5.25"x2@521k, 1980, DOS 2.5
8250 - 5.25"x2@1042k (double-sided)...
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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
The Amiga 500 has a very console-like experience for the most part when it comes to games. Treat DF0:, the internal drive, like you would the cartridge slot of a Super NES or a Sega Genesis. Just put your game into the internal drive, turn on the power and let the Amiga boot from it. :)
You can either:
Power the machine off, insert your disk, then power the ...
10
SD2IEC
SD2IEC is a free software which turns an ATmega644 microcontroller into an emulated VC1541. It attempts a near-complete emulation (I think REL files aren't implemented, but nearly noone ever used them.) The emulation also supports some common fastloaders, most prominently that of The Final Cartridge III.
You store .d64 disk images onto a FAT ...
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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 ...
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