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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. When the motor hits the end stop it will be unable to move further and will consequently stop. Once the Apple has done this, it will assume the head is at the ...
26
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, but that you could very directly mechanically lift the read-write head from the surface of the disk.
That meant that if you were quick enough to lift the ...
23
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 ...
19
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) to try to read the disks. Even then, some 2M disks will be hard to read — beyond the usual problems with old floppy disks, since 2M formats really push the ...
17
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 1 will switch 'manual' into 1571-mode.
OPEN 1,8,15,"U0>M0":CLOSE 1 switches back to 1541-mode
Additional Features in 1541 Mode
While the 1571 ...
17
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-sectored floppy drive, a 40 x 6 plasma display and even a printer in a package of about the size of a (quite large) travel typewriter, weighing 20 pounds.
I ...
16
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 arguably just enough time to realize you shouldn't have hit enter, and to pop the drive latch. Especially if you subconsciously realize it before you even hit ...
16
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 from a Linux LiveCD (or a flash drive built from one), you should be able to use the ddrescue tool which is designed for exactly this situation. It will find ...
15
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 sized computer. And only a few would work well on a lap. I wouldn't consider the T1100 be one of them.
Still, with the T1100 as cornerstone, I think the Morrow ...
15
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 luggable and has
Built In Media: Two 5.25'' SS/DD full-height floppies (190k)
Peripherals: 400 KB or 800 KB 5.25'' floppy drives, 10 MB hard disc, ...
13
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 could collide with each other if the drive was jarred.
However, the drive designs I'm familiar with have a mechanism to hold the heads and drive spindle away ...
13
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 platters with one track, so overall you get a cylinder).
One thing you are missing is that some floppy drives and nearly all harddrives have multiple heads, so ...
13
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 write standard PC floppies (1.44 MiB, perhaps 1.68 MiB; this includes most bootable floppy images), then buying a USB floppy drive will be cheaper than buying ...
12
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 more expensive drives and controllers to detect the problem.
As long as it didn't damage the computer such behaviours were considered acceptable to get the ...
11
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 ...
11
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 in the latter, they also had to be suitable for running some fairly advanced software as well as for introductory courses.
By the standards of the 70s, when ...
11
If you inserted the disk "upside down" the Apple //e would make a hideous noise like a vacuum cleaner.
Not sure what the 'vacuumer sound' should be. could it be that you're refering to the way the drive returns - and calibrates - to track. I would rather describe it as a fast clicking noise over some scratching.
Also, there was no different operation ...
9
I'm not sure if this is technically possible for the disk format you are asking about, but there is an open source project by David Given called FluxEngine that has been trying to read all kinds of weird and exotic disk formats by reading the magnetic flux changes directly - creating a sort of 'disk image' that can then be deciphered in software to ...
9
Yes, the sector size is software-controlled, to a certain extent. Every FDC command involving sectors or tracks takes the sector size as a parameter. The size is specified as a bit shift applied to 128, so sector sizes are of the form 128 × 2n (usable values go from 128 to 4096 on the original PC; there isn’t enough time to fit an 8KiB sector in a track ...
8
Another partial answer.
.d13 is a format for storing the 13-sector floppy disks that were used on the Apple II before mid-1980, by Apple OS's before before DOS 3.3; i.e. Apple DOS 3.1, 3.2 and 3.2.1, the earliest versions of Microsoft's Softcard-based Apple CP/M 2.2, and maybe by the first version of Apple PASCAL (not sure about that though); those floppies ...
8
I’ll limit my answer to common 3.5” formats on PCs, DSDD, DSHD, and SuperDisk, as listed in your question.
SuperDisk drives can be ignored as far as backwards-compatibility is concerned: they have two head assemblies, one for “standard” formats, the other for LS formats, and the “standard” head is equivalent to a high-density 3.5” drive’s.
The main concern ...
8
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 cylinder” mention appears, but those that do, other than the 5150 first edition, don’t reproduce this — see for example the first edition of the IBM 5160 Technical ...
7
bad news, the connector is simply a data port for the "PC-8031-2W" external disk drive unit. all of the 'smarts' are in this external box. this 36 pin connector is literally just 3 8-bit data lanes and ground.
7
ROM BASIC does not support any handling of floppies at all, but System ROM allows boot thru it's function table. Of course one could handle the disk controller 'manually' from BASIC - which is what the example does.
Routines
(All following values are according to TRS‑80 ROM Routines Documented)
The System ROM (3000h-37FFh) only supports booting a disk. There ...
7
If you want something more flexible than a USB floppy drive, but barely more expensive, and you're OK with beginner-level through-hole soldering and a command-line interface on the reading/writing tool, take a look at the FluxEngine.
The FluxEngine is a very cheap USB floppy disk interface capable of reading and writing exotic non-PC floppy disk formats. It ...
6
This is an incomplete answer.
https://www.pagetable.com/?p=1018 references an as-yet-unwritten article about JiffyDOS:
JiffyDOS, a 3rd party ROM patch for computers and drives, replaces layer 2 byte transmission of Standard Serial by using the clock and data lines in a more efficient way. Bus arbitration is unchanged. The controller detects a device’s ...
6
I can offer a partial answer only:
.dsk, .do and .po are all the same file format: sector contents only, implicitly ordered. The difference is that DOS 3.3 and Pro-DOS use different orderings, so it's fairly common to use .do or .po as a file extension in order to be explicit about which of those filing systems' orderings the disk image should be ...
6
As far as I know this laptop can’t easily be connected to a network, which leaves three options for getting software onto it:
transfer over the serial or parallel ports, using an appropriate cable and software such as LapLink or the built-in transfer tools in MS-DOS 6.0 or later, PC-DOS 5.02 or later, and DR DOS 6.0 or later;
the floppy drive;
directly ...
6
'Disc missing' may indicate that the disk is not spinning fast enough, or the index hole sensor is not working properly.
The most likely cause is a bad belt. If the computer is left idle for long periods the belt tends to deform where it goes around the motor pulley. So even though you replaced the belt only 'a few years ago' it is the first thing you ...
6
There's a number of terms which partially overlap here, and of course some people use the wrong word for a particular concept due to incomplete understanding. I'll summarise all the terms I can think of.
Block: the data residing on a single sector of a single track. This is typically between 128 and 512 bytes for floppy drives, depending on the vintage of ...
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