More than two floppy drives? 

The use of a progress bar for the ad/sponsor is a nice touch.

Tech Tangents and Adrian's Digital Basement on the same day! nice!

Two IDE channels, while redundant for most average users, uses would be multiple HDDs or CD drives (common to have a fast read drive and a slow burning drive). There are also performance benefits, two hard drives on one channel can only access one drive at a time (shared data bus), but two hard drives on separate channels can be accessed simultaneously.

You should fix that table, so shaky :)

The whole time i'm watching i'm thinking that table is gonna collapse Once again a lovely video and i love this oddball stuff.

In some bizarre universe, LinusTechTips is now making a video on installing 8 floppy drives in a single computer.

This brings back memories of working on my old Pentium II, with two hard drives and two CD drives (one reader, one burner). It was a horrible, cramped mess and the ribbon cables were never long enough :D

If you enable the external third or fourth floppy drive on the IBM PC/XT, the hard drive will be moved to D: or E:, respectively. I discovered this when adding a hard drive to my dad's IBM Portable PC, and was surprised to see it show up as E:, because for some reason its motherboard left the factory with the DIP switches set to indicate it had four floppy drives. Also some early pre-XT hard drive controllers which required a boot disk would assign the hard drive to A: after loading the driver software and move the first floppy drive to B:. This is also the way the TRS-80 works -- if you add a hard drive, it shows up as drive 0, and the floppy drives move up to become drives 1, 2, 3, etc.

I remember years ago someone on a retro computer discord had a fun 360k floppy that had been half-overwritten in a 1.2mb drive. On one of his computers it would read the original data, and a different would read the new data.

So many years of wondering what it would be like to have more than 1 FDD in one PC. I’ve actually been looking up how it would work, but this video is SO MUCH MORE SATISFYING!!! Especially seeing all those drives built into a truly legendary case! Shelby, thank you so much for this awesome video. It answers a lot of questions for a lot of people, I’m sure!

Another reason why many PCs came with 2 IDE channels is for many years each IDE channel would only run at the maximum speed of the slowest device on a given channel. This was more of an issue shortly ATAPI optical drives became common. Many optical drives only supported UDMA modes 0-2 (16.7-33.3 MBs x-fer rate.) Where later HDDs, especially 7200 RPM ones, supported higher speeds like UDMA 3-5 (44.4-100 MBs x-fer rate.) Later IDE controllers aren't supposed to have this issue but I remember this still happening up until at least the Pentium 3 days. Also, since both devices on a given IDE channel have to share the data bus it made a lot of sense to place a HDD and a CD burner on different IDE channels. Especially in the early days of CD burning when it was very easy to mess up a burn in progress due to a data under-run!

The Shugart 8" drives had four drive select wires. A jumper on the drive selected between "radial" drive select and "linear" drive select. The Linear select used one wire per drive for a max of 4 drives. The radial select used one wire to enable the drive, and the other three wires were BCD encoded. In this mode you could have a max of EIGHT drives on the cable! IIRC the 5.25" drives were similar, but could only handle a max of 4 drives (radial) or 3 (linear).

A few years back when I built my first modern computer instead of always having really old Frankenstein systems from my uncle he asked me about all the disc and disk drives and was shocked at how easy they were to set up. Lol I knew there were hoops to jump through for multiple drives but I didn’t know it was that annoying. Now I know why he was so shocked.

This finally explained to me one of the questions I've had for about 30 years now: why my very old XT hardware documentation about floppy drives seemed to be incorrect. Thank you so much for not letting me die unknowing!

I've only been following the channel since the trip to Canada. Even just since then, the camera quality has gone up. The editing and cuts to B roll feel smoother and more frequent,.which is more engaging, and even the scripting has really stepped up. This is just blowing my mind when it comes to quality and content. Great video, super cool and informative. You sir, are crushing it.

Fascinating video, took me back to my old days cutting my teeth on DOS, thanks for sharing, love to see old machines still in daily use.

I wondered about the weird TRS80 interface on other videos...but now I see they were right all along. What a *TWIST*!

Now I'd like to see a follow-up video showing you modding both an XT-FDC and a Sergey's FDC. :D

I never realized how lucky I was that TI used completely stock drives on the 99/4a until today.

A guy talking about old floppy drives and all their connections and other differences for 18 minutes. RU-vid algorithm knows me too well.

I REALLY need/want to get my Win98 machine to have 3 floppy drives for getting data to and from all my machines. Another awesome video, very well researched and I learned stuff. Only thing I'd tweak is the 4 drive IDE thing, that only became a standard thing sometime around the intro of the Pentium architecture, and it was not done for Hard Drive support, more for optical drives and other non-hard drive devices. When CD-ROM drives shifted from SCSI to IDE people starting realizing that a single IDE channel was not enough, and then later on when drives increased in speed it became apparent that having slower IDE drives on the same channel as the high speed HDD was degrading performance, so the demand became to add a second IDE channel on boards. So the evolution to 4 IDE drive support had not much to do with having 4 HDDs, more to do with performance and the desire to have multiple other IDE devices.

Thank You!!!! That's a subject that has always bugged me and information online is very scarce.

Love your videos!

The twist in the cable was introduced with the PC/AT and then carried over to the XT during its time of production overlap with the AT. Texas Instruments also used normal Shugart interface floppy drives with their controller for the 99-4 and 4/A using a straight through cable with all female connectors and special male/male connector PCBs to swap the ID lines for the two external drives while the single internal drive used a 34 pin 0.1" header to card edge cable. It's also possible to custom wire a cable and skip the little connector PCBs. Unfortunately TI neglected to make their floppy controller with double density support, leaving that up to the aftermarket. But there is a way to modify the TI controller to use 80 track 720K (3.5" or 5.25") drives as 360K single density. Most of the aftermarket controllers also supported 4 drives.

Incredibly informative video. I love deep dives like this. I wonder how 5.25 disk duplication worked on a large scale back in the day - though conceivably those machines wouldn't actually "read" or have a drive letter they would just write...

Wow wow wow!! Thanks for this video :) Gotta admit, i like retro stuff in general, but floppies have a special place in my heart. My first computer was a ZX Spectrum clone, and I was so jealous at the time of the more modern machines that had floppies since it was so much faster than tape :) Then i got an 8086 and started hoarding a number of floppies, some of which i lost last couple of times i moved, but i still have a great deal around. Setting up one of my old machines to have 3 floppies + my IDE zip drive was an idea I had bouncing in my head for quite a while now. Maybe i can learn something from your videos. Anyway, sorry for the rant. Love your content! Cheers!

<a href="#" class="seekto" data-time="236">3:56</a> Apple didn’t need an interface *board* for its floppy drives: it had an interface *chip* . This was because it didn’t bother with actual hardware to do the encoding and decoding of the magnetic signals: this was all done in software, courtesy of that hardware genius, Mr Steve Wozniak.‌

Mildly scared for the table wobble on the video. Very interesting video :)

Just a thought, but weren't there some early tape drives that ran off of the floppy controller too?

Man these old technology...is ine of my favorite I wish if some of these can be found in the market 😍

This was a lot of fun to see. Could you demonstrate more of that BIOS option menu in a future video?

Superb video as always! I tried doing the exact same setup as you but I used a BIOSless card. I did manage to get one of those DOS config.sys drivers working ... But really compatibility sucked and while the drive worked in DOS, disk imaging software had issues with the third drive. (1.2mb in my machine as well ) Even with your setup I'd imagine software like IMD still can only see A and B....

Hey hey you're finally talking about something I knew before hand! Still gonna watch it anyways because I love the production quality! One of my many Taiwanese clone PCs, based on the DTK Turbo 640 board, left the factory with two floppy controllers and 3 drives! One controller was configured in slave mode, which is an interesting thing to set up. The second controller was controlling the third drive, which because of the ancient hackjob of a BIOS and the old version of DOS I have to use to make that work at all, and the lack of a fixed disk controller (which crashes the garbage BIOS), the floppy drives are A, B, and C. Funny enough, I've got some weirdo Asian import no-name motherboards going all the way up to the early 2000s (AMD Socket 462) which list a "Third floppy support" in the BIOS and will let you connect a third drive on a different drive select on the same cable. I've never come across the actual cable, but jamming some wires in a breadboard I did actually manage to see it work, at least enough for Windows to show a disk drive in "F:" (That particular computer has two optical drives). Since most controllers internally support four drives, and since you can get BIOS extensions to make those extra two drives work, you should in theory be able to modify a standard diskette drive controller, or even an onboard one to allow four drives. Most off the shelf drive controllers you see in IBMs are pretty well documented Fairchild or Zilog parts or whatever, stuff you can find datasheets on without too much hair pulling EDIT: Haha, you talked about it in the video. The only BIOS I've seen that supports a second controller is that absolute garbage Taiwanese clone BIOS, which doesn't even do a proper memory test. No EGA support either, MDA or CGA *only*. It's probably the least functional it could be to make the machine work, but it does have that one random advantage that it happens to work with a second address card. Supposedly it supports the same for video cards and hard disk controllers, but adding a second video card causes the machine to act very strangely (switches between the cards at random, think displaying half a word on one card and the other half on the other), and adding a hard disk controller period will cause it to hang on boot Finding the jumper settings isn't terrible for most cards! Have you tried Total Hardware 99? Statson.org is a reupload with a more "modern" layout and lots of ads if you're more comfortable there. th99.infania.net is where I go to get all mine. Is your LS-120 drive really that unreliable? I've never had a problem with any of the three I have laying around, as long as you keep the heads clean and the rails lubed like any other drive it'll be just as reliable. The lack of direct hardware access might cause you drama, though. I have a lot more issues with iomega drives (ZIP, JAZ, ditto, Clik!, etc) failing and eating media. I'm interested in the "CA9277B-21" card you mentioned in the video, would you be open to dumping and posting the BIOS extension on that card?

In the 1990s, I decided to try and use an 8" drive on my PC, while keeping both 5.25" and 3.5" drives. My first 4-floppy FDC has been a controller made by GSI, with 2 x 34-pin connectors on the board. My setup was then A: 1.2M, B: 1.44M, and the 8" got the letter D: and was set as 1.2M in the BIOS. An 8" is really a big 1.2M drive, but with 77 tracks instead of 80. I could format blank 8" disks with DOS, and the stepper would knock 3 times at the end after track 77. No error message on FORMAT, that's normal, but I know I couldn't use the 3 last "non existing" tracks. Still cool by 1994 to write data and hear the loud stepper of the 8" drive. They were well gone by then! The challenge was to make the home made adapter from th 8" 50-pin bus to the standard PC 34-pin floppy. The 8" drives were in an external casing with its own 24V power supply, which is different and bigger than the standard PC 4-pin Molex. I still have all my equipment today, plus I bought the MicroSolutions CompatiCard IV in the early 2000s. This is the holy grail of disk controllers, and it also supports 4 floppies. It came with their special 50-pin to 34-pin floppy cable adapter, so I didn't need to use my home-made anymore, that was quite fragile (it was a piece of art, connecting thin wires between the 50-pin female and the 34-pin female, and if one got too loose, I lost a signal and got an error). I was glad to get the PCB adapter with 50pin and 34pin connectors from them... The CompatiCard IV is able to read/write FM Single Density, in particular the IBM 3740 format developped in the 1970s, which is 8", 77 tracks, 26 sect/track, and 128 bytes/sect. Although this predates the IBM PC, I was still able to read the data sector-by-sector, and take disk images, using the program ANADISK. The file size is 256,256 bytes, so 250.25 KB... I also got 86-DOS on that format, as well as early non-PC CP/M-86 versions from 1980-81...

Great video, Akbkuku!

Funny you mention the PS/2, as the models 25/30/40 were indeed limited to 2 floppy drives, but models above that were not, eventho that did require adding controller cards. For years I've had a PS/2 model 80 around which had 2 internal drives (2x 3.5" 1.44mb) and 2 external drives (5.25" 360kb and 5.25" 1.2mb). That was an officially supported configuration (I worked at IBM at the time and did support for PS/2 machines). This machine was used for archiving media, it also had an internal worm drive for storing archived disks. However, support for those extra drives was provided by the option roms (and related settings), not directly by the bios.

I never knew that you could get 4 floppy drive support or the cards to make it happen. Good bit of info that pal! i always thought IDE and SCSI were the ones to have for extra drives.

<a href="#" class="seekto" data-time="713">11:53</a> i actually quickly turned my head arround when i saw that reflection of yours.

Enjoyable as always.

Ahh, the IBM PC AT It was the bees knees at the time. Mine had two HD floppies and two 40MB HDDs. I had reasons ... Mostly, I was a developer and having the source file on one HDD and the output on the other almost doubled the speed. Two floppies were for making copies. Again, speed was the incentive. In the case of the floppies, it made copying much more that twice as fast. I should get a PC, and XT and an AT ... and possibly a 386SX (I had good memories of one). I'm sick, aren't I? Especially considering I have a bout 30 8-bit systems and a PDP-11/74 cluttering up my 'show room'. How about a Micro-VAX????

I've always wanted 4 floppy drive support for the same reason you did. I have never found a 4 drive controller in the wild, though, so you lucked out there. I didn't know about the XT FDC either. I will look into that. I remember watching a video on RU-vid (but can't remember from who) where they had a motherboard with 4 floppy support in the BIOS, and he needed to use 2 floppy controller cars with configurable IRQ and DMA to get it to work. I think it was some 386 board, but I could be mistaken. I imagine that's even rarer than finding a 4 drive controller. The one thing that would be really neat is if something allowed this and also enabled 3 mode support on the 3.5 drive, for reading that odd format on Japanese PCs that used 3.5 inch drives, but ran them as 5.25 1.2 MB drives.

facinating video as always

you have the coolest hats I swear

This is a very interesting topic.

Thanks for the video, I was always fascinated by that 4 drives theory (never seen more than two though). But please get a more stable desk :D

I think that's the first time I've seen someone populate all 6 bays in a tower. I do seem to vaguely remember the 4 drive set up for TRS PC's, but never had experience as my only TRS machine was a CoCo2 and even a single floppy was out of my price range. I think if I ever got into what they now seem to call "retro computing", I'd be one of those guys who would only use old media for kicks and for day to day fun I would use those kits I've been seeing that allow modern flash hardware to mimic floppies. Even back in the day, one of my goofy side projects was to put win 3.1 on a CD to see how fast I could install it. It seemed stupidly fast to me at the time, lol.

Those kinds of cards with extra controllers but no BIOS are probably useful for like mass disk copy operations where you write some custom software to address the ports directly.

LGR is salivating right now.

Many controllers supported up to 4 floppy drives. The big PC companies didn't often support more than 2. But many of the generic clones that were made from a collection of parts did offer up to 4.

I suck at soldering, but building a flux engine is easy enough and the software is kinda neat. Fully recommended.

Some machines used 80 track DSDD 5¼" formats with BIOS routines mapping sector sizes like modern hard discs do. This pushed capacity way above the PC limitations .

<a href="#" class="seekto" data-time="70">1:10</a> That was actually pretty hardcore dude 👏😲

Awesome video but a bit scary to watch. With all that table wobbling I was scared that the computer would fall over.

Dude I'm having a heck of a time getting one 5.25 floppy working in winxp. The bios supports and is selected to 5.25. The drive powers and spins but doesn't seek. Idk man maybe the drive is broken. Anyways awesome video you've helped thousands of people.

c: I'm more of a / person.

On modern computers I often use A: and B: for removable media, usually SD/MMC or MemoryStick cards.

I like the outro of showing the machine working on its own. It reminds me of the end credits for episodes of _Are You Being Served?_ when they would show product displays from earlier going haywire..... except, we don't want to see PCs actually going bad, unless it's a gag setup, like a smoke machine with lighting tricks.

Ohh man no seek sound test on all the floppy's. Love that sound. Still good and entertaining.

I like the video because it's hard to keep up with everything. The XT-FDC and Sergey's FDC is going to be worth checking out. The twist in the ribbons motor control is not an IBM thought, it's actually from hacks that were used to help techs swap out floppy drives and reduced the time to switch. The manufacturers picked up on it and adopted it as standard practice. The two common reasons we needed several floppies were 1) copying floppies over several drives at the same time reduced the time it took to copy floppy to floppy. If a person looks way back in the old catalogs they could find "towers" much the same way people can find cd towers. 2) more commonly, it was easier to load software by redirecting a drive already loaded with the next disk rather than simply flipping floppies. Most floppy controller boards had at least IRQ jumpers that the controller can be assigned, the real problem was figuring out which IRQ was free. While the on board bios supported A and B drives, it was largely because the controller was on the board, and it was common that the default system files were on the A drive, the B drive was included since the controller supported two drives. More floppy drives got an extended letter after the hard drive mainly because the bios support for four hard drives (in most cases) meant they had priority over the next available drives that is not in the bios. C,D,E,F were often reserved for hard drives unless there was one HD controller on the board then C,D. After that then the installer had to manually assign the drives either by pin or in the config,sys working with the software driver. The reason Manufacturers reduced the inclusion of floppy drives over the years was that by the time CD's started being used for software storage, the writing was on the wall for floppies.

Very interesting... thanks!

I need that XT-FDC :o

a few years ago I found an old PC almost like this with 4 drives in it (I forget the configuration, but it was a huge tower PC from the early to mid 90s I was guessing). It was $50, I wish I got it cause it was pretty awesome.

I fucking love Nextcloud. Been using it for several years, hosted on my own server. It's been immeasurably useful over the years beyond it's usual cloud backup services

Yes, I still have to do that on some of my older computer to back up data.

This was my childhood dream, was to have as much drives (floppy drives, CD ROMs, ZIP, etc), as possible.

Adding a second (or third or fourth) floppy controller works perfectly with Linux as long as you supply the io-Adress and IRQ on the kernel command line or the module command line - disclaimer, I am talking about kernel 1.0 or 1.2, not sure if this still works today. In fact I once took an "non-configurable" floppy controller and rewired the ISA connectors adress lines so the IO landed in a VERY strange place. Worked like a charm in Linux as fd2 and fd3 - I might had to mknod the devics manually under /dev/ but thats trivial. I am not sure if the minor nodes where like 0,1,2,3 or 0,1,64,65 but I think the later was true and it was visible from the kernel boot log. In hindsight FreeDOS could support that too as I remember it has an option for additional IO-ports for floppies. Maybe a seperate DOS driver could do the same but then I am not aware of anything like that.

You should add a 720K 3.5 inch drive, because although you can read 720K disks from a 1.44 drive, writing disks does NOT work reliably (supposedly due to magnetic strength or something)

I did some digging into the logo and and the model number on Shelby's card. I found a 5 year old forum post that mentioned the company called "Relialogic Corporation PTE Ltd." out of Singapore. I'd take it with a grain of salt, but it's all I could find after searching for well over an hour. I did uncover other cards that are suspected to be from the same manufacturer.

Good old I/O cards. Back then I got one from a friend and plugged into my Pentium MMX, so that there was another IDE channel, floppy channel, serial ports etc. I can't exactly remember (20 years back) what happened / whether it worked or not though. I think now we can just use 4 USB floppy drivers easily.

Drive letters were a design mistake.

It would be a interesting excersize to do something like this but also with optical drives.

Good video...

Amazing facts. I always wondered where is B drive installed 😂

The additional MR BIOS (Microid Research) has support for 4 floppy drives natively with two 2 floppy drive controllers. It replaces the original bios on the motherboard

Neat that you got a CryoFlux recently!

It is possible to install more than the standard two (IDE) floppies, in that you use SCSI FDD, internally or externally, connected to one or more SCSI host adapter.

IMO leaving the unneeded (for almost all people) 4 drive support is similar to the use of 2 digits for year representation. It doesn't require extra info/worry/etc. when its not needed in most cases (over than when you switch centuries... or are doing copying between formats in your example).

Wow, what a flashback. On the old atari ST you could use pc drives in it. Including the external boxes. And yeah you could mess things up if a drive was set at ID 3 or 4. The teac 3.5 drive 0 & drive 1 pins were binary, so it was actually a binary 0-3. For backwards compatibility. I really screwed with some friends back in the day by setting drives to 2 or 3 aka drives 3 & 4.

You might get the secondary floppy io address working by installing an xt-ide bios in a network card.

The controller card is from Promise Technology and they still sell 4 floppy controller cards.

I’ve got some of the LS120 drives in my Silicon Graphics Indy workstations.

I'm going to have to look into my old 286 at my parents' place because it has 4 floppy drives in it! 2x 5.25" and 2x 3.5", each size format with a DD and HD drive! I never looked into why or how all drives were supported at the time!

On my 1983 HP 150 Touchscreen the 3.5" floppy drive is B: and the 15mb hard drive is A: (unless you have it boot from floppy then the other way round). The joys of early DOS compatible but not PC compatible computing! It runs custom DOS 2.11 BTW and the floppy is not 720k but a 710k custom format so some special dos drivers need to read/write to them.

Conversely, as more and more motherboards drop support for floppy drives entirely, it's possible to assign the drive letters A: and B: to one or two hard drives / SSDs / USB drives et.c. Very interesting video by the way; I was aware that many FDCs had support for up to 4 drives, for example the uPD765 which is a very common IC - but again with the caveat that it can only support one /Motor-On signal. Whether the floppy drives themselves can decode the 2 Select lines to 4 individual IDs is another matter altogether, though.

Tech Tangents: A and B are reserved for floppy drives Me: but I can reassign in Windows my drive to A or B (meme)

They, IBM, released a expansion chassis for the PC and XT where you could put in more drives.

I love this

Hello I loved the video and even more the case of that pc. Can I ask what kind of case is that?

And on another note, the 1.2mb drive versus 360kb drive... that is a problem when overwriting a floppy formatted on a 360kb drive with a 1.2mb drive. The result of that would not be properly readable. But in itself, a 1.2mb drive can read both 360kb and 1.2mb 5.25" floppies without problems.

watching that giant monolith of a case sitting beside him rocking back and forth every time he moves makes me slightly uncomfortable.

Commodore Amiga supports 4 floppy drives natively, DF0,DF1,DF2,DF3 in any order, 1 internal, 2 internal, 1 int 3 ext, 2 int 2 ext. ect...

I have never gotten the chance to obtain such a big full-sized ATX case, especially one made of steel. Gloriously heavy indeed, and allot of space to put a smaller motherboard inside (or two!) and two power supplies (hard disk cavity was massive enough!), along with six (6) cooling/exhaust fans. Yeah, that's still my damn dream. xD Current machine runs GNU/Linux (mint), windows 10 on a secondary drive (fucking never use it lol), has 24GB RAM (DDR3) and quad core AMD Athlon(tm) II X4 620 Processor at 2.6 GHz along with AMD HD series graphics.

Indeed, with a dedicated 4 drive controller with its own BIOS extension, making a 4 floppy drive system isn't that hard. I have made such a system myself. Demo video is also on YT. Using 2 separate controllers with the secondary at port 370h is the real challenge though. It can be done if IRQs and DRQs are different between the 2 controllers. Then there is either BIOS support or an OS driver needed to access drives 3 and 4. Being unable to find a DOS or Windows driver for this, I used the BIOS extention from Sergey's FDC to realize this. This works, although it isn't very fast and stability in Windows 95 is an issue. However, unlike with a 4 drive controller, having 2 separate controllers allows one to read or write 2 different floppies in parallel in the same system --> try to achieve that with a standard 2 drive system; the first drive pauses the moment the second drive is accessed.

I still have my TRS-80 MOd I with 4x floppy drives. I dare not plug it in lest it burst into flames -- I'm sure the components are unstable, especially the caps. It hasn't been powered on since the late 80s. I just can't bear to get rid of it.

No picture of the inside with all of the IDE cables snaked around each other? Akbukuku please :(

Man they are so difficult to find, those 4 drive controllers. Really hoping there's enough of a push for these that someone comes up with a new solution.

having a floppy drive as C: would surely cause some interesting software problems :P

love your hat, got a new keyboard

I'd like to know how we used to install a master and slave HDD in... say, a 486, or a Pentium. When my HDD was dying, a friend gave me a second HDD, but I couldn't get them both working on the same machine at the same time. Thus, anything I wanted to save from the dying drive, had to be copied by 3.5" floppy as it was my only other option. I did get most everything transferred, but not everything due to the size limit of the floppy.

I had an Amiga that could take four floppy drives(drive 0 was internal to the computer, drive 1 was an external which had another external connector for daisy chaining in drives 2 and 3), and even before I got the hard drive, there was never an occasion where I'd need more than 2 drives, other than installing a new program. The cost wasn't worth the use case.