B: drive in computers?

Well, why hasn’t there been one? We have the floppy disk drive A:, the Hard disk C:, and the CD-ROM/RW drive D:–so why isn’t there a B: drive?


The B: drive used to be the second floppy disk drive in older systems that required 5.25 disk compatibility for example, or even older systems that just ran off 2 floppy disks without a hard disk.


if you had a (wintel) machine with two floppy drives, you’d have a ‘B’ drive (also, if you would connect your (single) floppy to the SECOND connectory on the floppy ribbon cable, IT whould show as ‘B’

A: primary floppy

B: secondary floppy

C: Primary HDD

(then it gets confusing)

Oh, I see what you mean. Maybe the B: drive should now be allotted for Zip disks, whatever they are.

Tricky. The assignment of drive letters for the first two floppies is one of those hard-wired things dating back to the earliest days on the IBM XT, before even microcomputer hard drive standards were set. If you could make such changes and still have a system compatable with existing hardware and software, there are more interesting targets, such as the number of hardware interupts, memory addressing, hard drive bandwidth… Some of these are under review and advancements are being made, but salvaging the letter “B” isn’t a super-high priority.

I tend to use the B drive letter for a temporary fake drive, for when some software insists on using a floppy. If you do “subst b: c:\mydir” then “drive b” is just a pointer to the c:\mydir directory, but software that’s hardcoded to want to use either drive A or drive B will be happy.

IRQs can be shared by new devices, or just engineer devices to function without interrupts.

The PC architecture is so antiquated though it’d be much better to start from scratch.

The b: drive can also be used if you are doing a floppy disk copy, even if you don’t have a real b: drive. Copy a: to b: and the system will map b: to a:, same drive, different floppy. Then swap the floppy disks.

Not so useful nowadays, but was extremely handy in the days of single disk drives and small hard disks.

But the whole drive letter thing and architecture is pretty obsolete. The only reason for keeping it is backward compatibility.

Thats right. Your A: drive is also your B: You should be able to access it from Dos., say copy A: B:

Heh. I figured when I first saw the thread title that this was a question by some young whippersnapper who didn’t remember the good old days before all these fancy-schmancy things like hard drives and CD-ROM drives, when, if you wanted to copy a file, you put one floppy disk in drive A: and another in drive B:
[Grumpy old man]And we liked it that way![/Grumpy old man]

Ha! On my old C64, when you wanted to copy a disk, you put it in the drive, let it scan for 30 seconds, removed it, put in the destination disk, let it write for 30 seconds, and then repeat about 8000 times.


Letters for disk drives is sooooooooooooo Microsoft… :wink:

Spoken out of true ignorance. I don’t know how far back drive letters go, but we had a Wang mini from about 1975 that had three drives (8", BTW) called A, B, and F. The latter was a fixed drive, although I don’t think it was a hard drive, but I guess it contained the OS or something and was supposed to be fixed. I don’t recall what the Apple II did, but I assume that if you had two drives there had to be a way to address them. The most common OS in those days was CP/M (control program for microprocessors) and it certainly used drive letters. If you wanted to copy from drive A to drive B, you said something like
PIP B: A:filename
(I am not real sure of the syntax, but I am sure that the target came before the source.) I believe that PIP stood for peripheral interchange program, anyway, something like that. When Tim Paterson, working for Seattle Computing, wrote the first version of what was to become IBM-DOS, AKA MSDOS, he changed it to the more logical
copy a:filename b:
Right now, 26 devices seem to be enough for all forseeable needs. Of course, in 1968 two digits were enough to store the year for the forseeable future. (I have heard that the ISO that year came within an eyelash of mandating 4 digit dates and the US military screamed to high heaven that they would have to recode everything, so it was left as an option–that no one took.)

Once upon a time 8 bits seemed enough for the i-net. After all, who could imagine more than 256 computers hooked up. Sometime around the early 80s, they moved to 32 bit addressing since no one could imagine 4 billion computers hooked up. There are not in fact 4 billion computers hooked up, but the IP addresses are distributed in blocks and many addresses are unused. At any rate, they are seriously considering moving to 160 bits which is getting into the number of electrons in the universe. So each electron can have its own IP address. And one of these days, the drive letter spec will disappear too. And it will be a wrench as all these changeovers are. But I still find it very convenient as I do most of my real computing from a DOS (or 4NT) prompt. I hate going through menus.

a 5.25" in fact. It doesn’t work as well as I’d like, but I’ve been unable to find a replacement.

Re C64-Either all my C64 drives are bad, all my drive cables are bad, or all my disks are bad. Having all those C64 disks and not being able to run them is Very, Very bad :frowning: :frowning:

On the Apple II, the drives were accessed by drive number. D1 was drive 1 and D2 was drive 2. If you had more than 2 drives on your computer, you would also specify what slot the drive adapter was in. Normally it was slot # 6 and you would use S6. Example: If you wanted to get a listing of the files on the second drive that was attached through slot 5, you would use the command: CATALOG, S5, D2.

We’ll get on that as soon as you are ready to re-write every software app still in use from the last 20 years. :smiley:

Heh. Load “$”,8

[hijack]You know, I still have a C64, 1541 and 1702 still fully functional. I last fired it up a couple years ago to try out subLOGICs Flight Simulator II. Man, was that bad.[/hijack]

DocCathode, funny, but I’m about to throw out my 5.25 drives. I can’t find any use for them.
Yep, the legendary B: drive.

      • On a standard IBM-PC machine, drives A and B are always floppies. There’s three disk controller chips, controlling two drives each. They are assigned their letters on startup and the first one run is always the floppy controller, and the other two are the IDE controllers.
  • You can still buy “refurb/tested” 5.25 drives from a couple of places, but they get quite a lot for them- $100+. I looked a while back and never found anyone selling any new ones, or any cheaply that weren’t simple take-outs (condition unknown). A common problem is with the three different units I pulled out of a shop’s junkpile: the drive spindle rotates all the time. I dunno if they will write anymore, but I know that they will still read, so I decided to just install one in the case and leave the cables unconnected until I have a need to read a 5.25 (-if ever, that is. I hate the idea of not having any way to read media that was as widespread as 5.25’s were). - DougC

My mother invested in an extra 1541 drive for the express purpose of not having to do that. It also made using GEOS easier. Comma eight comma one forever baby! :smiley:

For a while there, A: was usually the 5.25" floppy and B: was the 3.5" floppy – at least on the couple of systems my family got that had both. I don’t think that we ever had one with two 5.25s, but by the time we could afford an IBM clone 3.5s had been out for some time. Drove me nuts, because the little bastards weren’t floppy at all, and I felt horrible not keeping 'em in envelopes …

… damn I feel old. Reminiscing about obsolete technology at the age of 21. You young whippersnappers.