Designing and constructing a floppy drive from scratch - Page 1
Forum section: electronics / projects

author: Banned 05.11.2017
author_rank: Contributor
timestamp: November 02, 2017, 11:32:01 pm
content: Hi friends,I've been wanting to design and build a floppy drive from (almost) scratch, the only things I will be using are the read/write heads, the motors/mechanical parts.The rest I want to build from discrete logic, both digital and also analogue where needed.I have a good theoretical understanding of the physics of electromagnetism, but I'm not sure it will be enough.Does anybody know of a book or online material on the engineering of floppy drives? Either 8, 5 or 3 inch formats. Preferably 8 1/4.Thing is I really want to do this, and I will no matter what, BUT I don't quite know how a floppy works.I see they use frequency modulation to write the magnetic data. What does this mean physically? I also know that clock data and data data are written together, so that a signal would look like a clock pulse, and then data after that. This means a low pulse on the clock, and then if there's another low pulse after that it's a 1, if not it's a 0. Does this qualify as FM ? Is this what they mean by it ?Also, the signal coming from the head, what does it look like ? Wiggly AC pulses right ? So I'll have to clean it up with a good ADC.Thing is, I don't need to be compatible with existing formats at the beginning. As long as I can create a drive that can write and retrieve data in SOME format, that will be enough.So all in all, I will have to take the head, create some digital logic to control it, and then send some pulses in some order to be written.Can anyone reccomend me a text on floppy drive engineering? Does this even exist ?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 02, 2017, 11:48:50 pm
content: http://www.ti.com/lit/an/snoa710/snoa710.pdf

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 02, 2017, 11:52:31 pm
content: So if you are using all the mechanical components from an existing drive, then you aren't really "constructing a floppy drive from scratch".You are constructing a DRIVE CONTROLLER (the electronic bits) from scratch.Haven't you already started a rather extensive thread on this subject? What is different about this one?Weren't most of these questions already asked and answered?Are you not able to find data online?You could learn most of what you are asking by simply getting a drive and a few discs and looking at the signal steam from the head on an oscilloscope.The first generation of floppy drives were pretty primitive. Pretty much as simplistic as you would imagine.In successive generations, they started improving storage density by attacking the problem from all angles.Doubling the capacity by using both sides of the disc.Using higher clock rates for reading/writing.Compressing the data using RLL (https://en.wikipedia.org/wiki/Run-length_limited), etc. etc.

author: alpher
author_rank: Frequent Contributor
timestamp: November 02, 2017, 11:54:46 pm
content: AFAIK there wasn't 8and1/4" floopy only plain 8", look for the Shugart floppy documentation.Floppies are probably the best documented tech out there.FM, MFM, endec, etc. lots of info out there.

author: rstofer
author_rank: Super Contributor
timestamp: November 03, 2017, 12:06:01 am
content: The only drive I am familiar with is the 8" IBM 3740 style. Yes, it used FM encoding and in order to capture the data there was a phase locked loop PLL that restored the clock from the stream. This was the hard part. Analog...Then I ran the stream into a Western Digital 1771 Floppy Disk Controller chip, added some address decoding logic and, voila', a floppy for my Altair 8800. Still have all of it.But you said discrete... Some time in the mid '70s, Motorola published a hardbound microprocessor applications manual. In the book there was a floppy controller that used discrete TTL to recover the data instead of an integrated controller chip. There was a LOT of logic.Page 17 here gives the track layout:http://bitsavers.trailing-edge.com/pdf/ibm/floppy/GA21-9182-3_Diskette_General_Information_Manual_Sep77.pdfIf you look at the index pulse, you will see it is followed by a gap then a sync field to lock up the PLL, then an address mark which must be compared in logic. Basically, there are ID fields and DATA fields. Lots of comparators to match the requested sector ID in the ID field with the ID just read from the disk.I wish I could find that Motorola book, I used to have a copy, but I dumped it a long time back. Silly... I THINK this is the right book but I can't prove it:https://www.alibris.com/Microprocessor-applications-manual-Motorola/book/4349637It's pretty cheap (before shipping) so there isn't much to lose!If you can find a 1771 datasheet, there will be a PLL circuit included. There are other similar devices, maybe they will help.

author: LaserSteve
author_rank: Super Contributor
timestamp: November 03, 2017, 01:31:51 am
content: See the examples page here, and scroll down to the floppy decoder.. Your looking at the web site of a former designer for Rola, one of his specialties was floppy...http://www.analog-innovations.com/SED.htmlSteve

author: BradC
author_rank: Super Contributor
timestamp: November 03, 2017, 01:49:30 am
content: Quote from: Engineer321 on November 02, 2017, 11:32:01 pmThis gives encoding methods, timing diagrams and a full schematic of the controller. It's probably a decent start point for at least looking at the timing, sync and encoding methodologies.http://bitsavers.org/pdf/intel/iSBC/9800420A_iSBC_202_Hardware_Reference_Sep77.pdf

author: BradC
author_rank: Super Contributor
timestamp: November 03, 2017, 02:00:00 am
content: This is also about as basic as it gets for the Analogs, although it does use an MC3470 integrated read amplifier.The Apple disk implementation was neat as Woz didn't use the index hole, so the on-disk encoding carried all sync data embedded, and the controller card and associated OS routines were a great example of elegant simplicity.(edit) Huh, drawn by Dave Jones.

author: Banned 05.11.2017
author_rank: Contributor
timestamp: November 03, 2017, 07:54:40 pm
content: Quote from: Richard Crowley on November 02, 2017, 11:52:31 pmWouldn't the data on the scope be changing too fast to be readable ? The data is not regular either and will be all over the place and changing too fast.Would it be possible to see it by using some kind of triggering?

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 03, 2017, 08:06:53 pm
content: Quote from: Engineer321 on November 03, 2017, 07:54:40 pmThe data rate from a floppy disk was very slow compared to what modern oscilloscopes will show.QuoteBut those changes will very graphically show you the differences between zero and one.QuoteSure. You would use various triggering and horizontal rates.You would look at a few hundred ms sweep to see the overall layout of the entire track.And even have the sector hole detector on another channel to see the timing relationship.Triggering on the sector hole would be good for viewing the entire track. (Or viewing the first sector in the track.)And you would "zoom in" to see individual sectors.And then zoom in more to see how the ones and zeroes are written.That schematic from Apple doesn't even show the sector hole signal because Woz was "flying blind".He was either assuming the exact speed of the spindle, or wasting a lot of space with a "guard band".

author: Banned 05.11.2017
author_rank: Contributor
timestamp: November 03, 2017, 08:25:13 pm
content: Quote from: Richard Crowley on November 03, 2017, 08:06:53 pmFantastic. Do you have experience working with floppy drives and/or controllers? Do you understand the process or writing and reading the physical data onto the magnetic material ?it would seem to me to be an "easy" process on the surface. By that I mean that the actual writing of data is simple, just a coil of wire around a C shaped conductor etc. What I am kind of confused about is why the clock data is written together with the data? If one writes the data only and uses an external clock what would be the problem ? Would the external clock go out of synch with the data? I'm not quite sure?Also what is the PLL used for?

author: glarsson
author_rank: Frequent Contributor
timestamp: November 03, 2017, 09:18:24 pm
content: Quote from: Richard Crowley on November 03, 2017, 08:06:53 pmVery few floppy systems used a sector hole (hard sectoring). Most floppy systems only used the index hole to indicate the track start (soft sectoring). However, both systems "fly blind" as no speed information within a sector or track is provided to the controller by the drive. The sector hole only provides a way for the drive to verify that a disk was inserted (assert the ready signal) and to lay out the tracks in a neat way (all starting at the same "time"). The Woz method makes no difference except that the tracks start at a random point.

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 03, 2017, 09:33:20 pm
content: Quote from: Engineer321 on November 03, 2017, 08:25:13 pmOnly the general principles.QuoteYes, that is basically it.QuoteBecause, otherwise there is no clock to read the data with.QuoteYou can't depend on a cheap floppy drive (or even a gold-plated military/aerospace drive) to stay "in sync" with any external clock. That is completely beyond we we can expect here in the Real World.QuoteIt is guaranteed to go out of sync.QuoteTo recover the clock!

author: dexters_lab
author_rank: Unknown
timestamp: November 04, 2017, 12:30:38 pm
content: have a search around on the Shugart floppy interface as documents will often include theories on FM and MFM encoding, track and sector synchronisation etc so should form a good primer for making something yourself.The members of the Kryoflux community forum are all highly knowledgeable about the nuts and bolts of floppy drives so i would recommend heading over there as they often have to deal with strange floppy disk formatsfloppy formats can be very simple, the 8" floppies from a piece of video equipment i have been looking at recently have no sectors and rely on just a single track of data with some synchronisation bytes so you don't have to have the complexity of track sectoring

author: TK
author_rank: Super Contributor
timestamp: November 04, 2017, 01:06:05 pm
content: Quote from: glarsson on November 03, 2017, 09:18:24 pmAnd it makes it possible to use both sides of the floppy disk by just cutting the write protect notch on the other side and inserting it flipped.

author: rstofer
author_rank: Super Contributor
timestamp: November 04, 2017, 05:38:47 pm
content: Speed information was included by way of the Sync bytes (inside the Gaps) that locked up the PLL. The PLL was the heart and soul of the IBM 3740 disk drive.http://deramp.com/downloads/floppy_drives/FD1771%20Floppy%20Controller.pdfPage 13http://info-coach.fr/atari/hardware/_fd-hard/AN-505.pdfPage 4 of this document shows one approach for creating the PLL which, ultimately, results in FDClock and FDData to the controller chip.https://archive.org/details/Western_Digital_1771-01_Application_Notes_19xx_Western_Digital

author: Banned 05.11.2017
author_rank: Contributor
timestamp: November 05, 2017, 12:31:41 am
content: Quote from: rstofer on November 04, 2017, 05:38:47 pmHow many clock cycles does the PLL have to synch to the signal? Also, what clock is there to use before the PLL has caught up with the clock in teh floppy ?

author: amyk
author_rank: Super Contributor
timestamp: November 05, 2017, 03:47:31 am
content: Looking at the (freely available) ECMA standards on floppies would also be a good idea.58,59,69 (8")66,70,78,99 (5.25")100,125 (3.5")

author: Banned 05.11.2017
author_rank: Contributor
timestamp: November 05, 2017, 04:51:01 am
content: Quote from: amyk on November 05, 2017, 03:47:31 amI think it would be a good idea if you stopped posting on here since you indicated that you don't think I have the "aptitude" to take on such projects.

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 05, 2017, 04:54:20 am
content: Quote from: Engineer321 on November 05, 2017, 12:31:41 amThat depends on how good the PLL circuit is. Early discrete-implemented circuits were pretty slow by modern standards. Later generations of specialty IC PLLs were much better, and that was a key contributing factor to the increase in capacity of floppy (and later hard) drives. Of course, if you really want to make a PLL out of discrete components, you have a major project on your hands. Good luck getting anything functional before next year.QuoteA common solution was to insert some fixed amount of ones before the data starts to "lock-in" the PLL.You really have a lot to learn about encoding and decoding asynchronous data. Designing discrete circuits to read and write magnetic media (whether tape, floppy, or hard drive) will make designing a CPU look like child's play.

author: gnif
author_rank: Unknown
timestamp: November 05, 2017, 06:04:35 am
content: Quote from: Engineer321 on November 05, 2017, 04:51:01 amI think it would be a good idea to be respectful before you get banned.You should note that the questions you are asking show your level of understanding and ability.I am no EE, I dabble in electronics, hack on things, etc.. Yet even I understand the need for an encoded clock with the data (clock drift, thermal expansion of the media, thermal expansion of the read heads, belt slip, someone bumps the drive, just to name a few). Even a much more more modern and precision device in comparison (CD/DVD/BR) encodes timing and also tracking information in a sub channel on the disk.People are pointing you at information that will answer your questions, go and read it, appreciate they spent their time trying to give you a leg up. This forum is very friendly to those willing to put the required effort in to learn.

author: Banned 05.11.2017
author_rank: Contributor
timestamp: November 05, 2017, 01:55:10 pm
content: Quote from: Richard Crowley on November 05, 2017, 04:54:20 amYou really have a lot to learn about respecting other people before they tell you to FUCK OFF. Hope you get it now.I have a master's degree in mathematics and I am doing a master's degree in microelectronics. Magnetic media are irrelevant today. I am doing it for fun. I am 1000 levels above your old ass.And oh, about designing a CPU being child's play, go tell that to Intel. I bet you yourself couldn't design even a simple 4bit CPU.Here's a simple serial tape read/write circuit that works:https://diyhacking.com/make-uart-cassette-tape-interface/That should show you that getting started in designing a simple circuit to read magnetic media is not as hard as your pea sized brain thinks.Best Regards

author: Banned 05.11.2017
author_rank: Contributor
timestamp: November 05, 2017, 01:59:17 pm
content: Quote from: gnif on November 05, 2017, 06:04:35 amYou are no EE ? Your profile photo does show that. You look more like a clown.You know nothing about my own efforts so you better shut your little faggot mouth up as well.If you are no EE, then don't try to teach those who are, and try to make yourself sound like you're better, because you aren't. You are just a little loser.It's easy to say you understand the need to encode a clock together with data when you yourself has heard it from others, and has never even designed a relevant electronic circuit yourself, as a "dabber".This forum is for those willing to answer questions, and not for those willing to take other's questions and mock them, otherwise you might make them angry, and they will tell you to go bury your head into a shit hole, where it belongs.

author: Banned 05.11.2017
author_rank: Contributor
timestamp: November 05, 2017, 02:01:38 pm
content: Quote from: Richard Crowley on November 05, 2017, 04:54:20 amYou surely know nothing about PLL's. I have built many PLL's before out of discrete components, and I did it in less than a week. It seems your old brain is too slow. I feel you buddy.

author: gnif
author_rank: Unknown
timestamp: November 05, 2017, 02:13:01 pm
content: Welcome to ban land. You are one of those idiots that believes that because they have a 'Masters' they are better then the rest of us. My work speaks for itself, in this community and others, you clearly have no idea who you are talking to.Quote from: Engineer321 on November 05, 2017, 01:59:17 pmOkQuote from: Engineer321 on November 05, 2017, 01:59:17 pmHow old are you? You're coming across like a child.Quote from: Engineer321 on November 05, 2017, 01:59:17 pmYou're not going to get far in this world in any industry. I bet you clash with just about everyone you feel is beneath you. I don't need to try to make you think I am better, nor do I really care if you or others think if I am, it's not important to me, just as it's not important to most people, we all grow out of that need when we leave adolescence behind.Quote from: Engineer321 on November 05, 2017, 01:59:17 pmIf you had any brains at all you would know that a oscillator is never perfect and has drift, it's a very simple principle and limitation, and one of the first things an EE student learns... you don't need to be a rocket scientist to know that if you set two clocks to the same time they will gradually lose sync with each other.Quote from: Engineer321 on November 05, 2017, 01:59:17 pmYour questions were answered, you were given detailed information to research. If you want to get angry that we wont do your homework for you, then that's your problem. Grow up and stop acting like a little kid.QuoteYou need to get a better grasp on the English language. He did not state that designing a CPU like yours was so easy a child could do it. He stated that designing a CPU like yours is very simple in comparison to what you are asking. Foundyour websiteby the way... not that impressed for someone that has a 'Masters'.

author: BradC
author_rank: Super Contributor
timestamp: November 05, 2017, 02:15:09 pm
content: Wow, that escalated quickly.

author: gnif
author_rank: Unknown
timestamp: November 05, 2017, 02:48:26 pm
content: Quote from: BradC on November 05, 2017, 02:15:09 pmNot as quick as you would think, I had to lock another of his threads earlier today due to abuse also.

author: BradC
author_rank: Super Contributor
timestamp: November 05, 2017, 03:08:12 pm
content: Quote from: gnif on November 05, 2017, 02:48:26 pmAhh, the website link was the trick. He's been around before and from memory it ended the same way last time around.

author: oldway
author_rank: Super Contributor
timestamp: November 05, 2017, 09:37:28 pm
content: Too crazy to be believed...They have internet in psychiatric hospitals ?

author: Ian.M
author_rank: Super Contributor
timestamp: November 05, 2017, 10:03:15 pm
content: What got to me, apart from the abusiveness, and led me to the conclusion that the O.P's grasp of reality in general, and signal processing in specific was fragile, bordering on non-existent, was his contention that understanding a NE555 based 300 baud audio tape interface that used a keyed CW 4Khz carrier would in any way help in the understanding and development of appropriate signal processing electronics for a floppy drive. Even a 40 track double sided 100KB per disk format must store 10Kbit/track, and assuming a 300RPM drive allowing 20% overhead for sector headers etc, that means a baud rate of 60K, more than two orders of magnitude faster than can be expected from the crude tape interface he believed to be relevant. The difficulties only increase if one is trying to reproduce the signal processing of a PC compatible HD 3.5" drive.Its like believing that slight experience operating a Mamod model steam engine would help you single-handedly build a Mack truck from individual parts without the plans!

author: timb
author_rank: Super Contributor
timestamp: November 06, 2017, 05:44:08 am
content: Quote from: Ian.M on November 05, 2017, 10:03:15 pmThe worse part is even that tape interface is pretty terrible. It might work for recording and playing back on the same tape recorder, with brand new data quality cassette tapes, but I doubt it would be very reliable when recording on tape deck A and playing back on deck B. There’s no hardware to compensate for the variability of speed between tape decks. There’s no filters on the RX side to help lock in to signals recorded on poor or well used tapes.Reliably writing to and reading from magnetic audio media is actually kind of involved! (Nowhere near as involved as a floppy or hard disk, obviously, but still more than meets the eye, none the less.)If anyone is interested in resurrecting old data from audio cassettes, issues of Byte from the late-1970’s have several good circuits for cassette interfaces. (In fact, they helped standardized the timings, coding and mark/space frequency used, which subsequent commercial microcomputers with built-in cassette interfaces implemented, making data interchangeable between systems!)

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 06, 2017, 06:04:52 am
content: I can honestly say I'm a bit surprised about his reactions to some of the people here. I can understand how insecure people or folks without coping mechanisms fly off the handle when confronted with any sort of criticism or doubt, but in this case even people who just kept to the subject got viciously attacked. That's not helpful at all.You have to feel sorry. Unless you're a prodigy genius able to solve problems no one else can, you won't be accepted in any kind of research or work environment this way. Most industries are surprisingly tight-knit communities and once you burn through your credits, it's not easy to restart.

author: tooki
author_rank: Super Contributor
timestamp: November 06, 2017, 01:33:43 pm
content: I honestly believe this is a case of strong Dunning-Kruger.

author: BradC
author_rank: Super Contributor
timestamp: November 06, 2017, 02:40:47 pm
content: Ta pocketa pocketa pocketa.

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 06, 2017, 02:54:30 pm
content: Well, it has taught me to ignore these kinds of questions in the future.

author: iainwhite
author_rank: Unknown
timestamp: November 06, 2017, 03:02:21 pm
content: Quote from: BradC on November 06, 2017, 02:40:47 pmAha - someone else who likes James Thurber

author: Kalvin
author_rank: Super Contributor
timestamp: November 06, 2017, 03:55:14 pm
content: As the 56k modem thread is now locked, here are two pointers for those who might be interested in the voice-band modems and implementations:"V.34 Transmitter and Receiver Implementation on the TMS320C50 DSP "http://www.ti.com/general/docs/litabsmultiplefilelist.tsp?literatureNumber=spra159Partial implementation using a PC with an audio card: "Here is the generic Linux Modem. This modem is totally software, it means that all the DSP stuff is done by the main CPU, as in some so called "winmodems"https://github.com/geofft/linmodemImplementing a V.90 modem will require some effort. More info can be found from the Google search.

author: rstofer
author_rank: Super Contributor
timestamp: November 06, 2017, 07:04:08 pm
content: There is a collection of 'ignore' selections in the Profile->Account Settings area. I'm beginning to think it might be a useful feature.I actually spend a bit of time researching topics before I reply and, in a few cases, that time is wasted.

author: MK14
author_rank: Super Contributor
timestamp: November 06, 2017, 08:06:32 pm
content: Quote from: rstofer on November 06, 2017, 07:04:08 pmNot necessarily a complete waste of time. I've actually enjoyed (especially the technical aspects), reading this thread. Some of the linked to articles/PDFs are apparently very interesting (I really like vintage computer stuff).Pity that the OP turned out to be a troll or something. I realised very early on (from other threads), that the OP was very likely to be a returning troll (Paulo etc). But kept quiet about it, in case I was wrong and/or they had learnt from the errors of their ways, and were going to be polite to people and NOT get into silly arguments.It's crazy how 100K or a megabyte, is so tiny these days. Yet in older times, it needed huge engineering effort, even to produce a 720K/360K etc floppy disk system.I think the early hard disk systems, were massive (the size of many washing machines), and only had about 4,000,000 bytes capacity. I think one of Dave's videos, takes apart (teardown), a huge old hard disk system.It's well worth watching, if you have not already seen it. Here it is:

author: medical-nerd
author_rank: Regular Contributor
timestamp: November 06, 2017, 09:18:41 pm
content: Quote from: MK14 on November 06, 2017, 08:06:32 pmI wish to thank everyone that has contributed their time in answering this person's questions. I have found the answers both informative and humbling in demonstrating the wide knowledge of members of this forum.Please don't stop - as it is inspiring to us doing this as a hobby.Cheers

author: MK14
author_rank: Super Contributor
timestamp: November 06, 2017, 10:12:57 pm
content: One thing that I often wondered about (as regards floppy disks), a while ago. Was why did floppy disks (on PCs), take so many seconds (seems like 10 seconds or more), to first list its directory (catalogue) ?Because in principle, the tracks can be read fairly quickly, so surely it should just be a matter of spinning up the spindle motor and reading a few tracks (and hence sectors) ?Maybe the spindle motor spin up time, is longer than I imagine (1 second approx) and/or it takes a while to speed stabilise enough for sectors/tracks to be read, reliably. Also, maybe it was only reading things in one sector at a time (because ICs to automate that task, tended to be, post the floppy era) ?So if it has to wait for the disk to spin around until it gets the next sector and there are many sectors to read in, in order to get the full catalogue.Then, maybe I have just answered my own question.Also, another quick question.Annoyingly, 3 1/2 inch floppy drives, seemed to "break", even if they are mostly unused. If the PC is regularly powered on and approximately 5 years (because many electronic things can last many times longer than this) has passed. So presumably something breaks, eventually. I wonder what ?They were eventually seemingly built downto a price (of something like £10/$10), when they were common place.Maybe a capacitor or IC ?

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 06, 2017, 10:20:18 pm
content: If something breaks without use, especially if it's a device that relies or incorporates mechanical motion, the first thing I'd look for is rubber bands, belts or something similar. Electronics used to be full of them and they don't tend to last very well.

author: MK14
author_rank: Super Contributor
timestamp: November 06, 2017, 10:43:10 pm
content: Quote from: Mr. Scram on November 06, 2017, 10:20:18 pmThat is a good point. There are a lot of mechanical elements to floppy drives and the mechanisms tend to be relatively lower quality than precision hard disks, in general.Rubber belts are problematic (in equipment), I agree. I hadn't thought about that aspect of the floppy drives. I know the ones in ancient equipment (1960's/70's etc), are well known to turn to mush, after 10 or 20 years or so. Even if kept in ideal conditions and never used.£10/$10 = cheap mechanicals and rubber belts. So it not lasting long from that point of view, makes sense as well. Somehow I thought it was the electronics which was playing up. I never investigated why the many floppy drives I replaced over the years broke. Since they were around £7 or £8 (or £10/11, if you didn't shop around) when they were very common and cheap, I'd just swap any which broke.

author: Ian.M
author_rank: Super Contributor
timestamp: November 06, 2017, 10:52:24 pm
content: There shouldn't be many critical elastomer parts in a 3.5" floppy drive as they are usually direct drive. Dried or gummed up lubricant is more likely - if there's any stiction in the head movement or the spindle motor fails to reach full speed before the controller + driver times out, or varies in speed as it rotates, the drive will be unusable.

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 06, 2017, 11:00:15 pm
content: Quote from: Ian.M on November 06, 2017, 10:52:24 pmYes, later versions were 1/2 (and even 1/3)-height and featured flat-motor, direct-drive spindles. Similar to the spindle motor in modern hard drives.But the original "full-height" models (both 5 1/4 and 8 inch) used rubber belts between a separate conventional motor and the spindle shaft.QuoteIndeed. The manufacturers probably weren't planning on even a 10-year life-cycle for those things.

author: MK14
author_rank: Super Contributor
timestamp: November 06, 2017, 11:09:07 pm
content: Quote from: Richard Crowley on November 06, 2017, 11:00:15 pmI think in the peak of the heyday (when you'd go out and buy the latest 300 MHz system, then next week 350 MHz systems would come out). I was probably upgrading my PC every 6 months (e.g. bigger hard disks), and essentially changing the whole system, every year or 18 months.Fortunately, those days seem to be over (it was costing an arm and a leg).These days, you gain about a 5% speed improvement, after 4 years, if the wind is blowing in the right direction, and you use the "right" benchmarks. (Ok, I just exaggerated, but single core/thread processing speeds, seem to have flattened out, with not much speed improvement per cpu generation).Even hard disk capacity increases, have slowed to a trickle, these days. 3T being about the sweet-spot still, if you don't want to spend too much on hard disks. But SSDs may give huge capacities, for little money, eventually.

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 06, 2017, 11:23:12 pm
content: Quote from: MK14 on November 06, 2017, 11:09:07 pmRealistically, it's been about a 5-10% performance increase per year the past 5 years. That's incremental by any standard and not something you'd notice without putting some effort into benchmarking things. However, the main focus has been on energy consumption, so the performance per watt has actually increased dramatically. The shifted focus can probably be attributed to a combination of factors, such as more awareness of the public in regards to conserving energy, the shift towards mobile devices, not having a lot to gain from even more speed in a single processor core, a lack of direct competition and problems with the very physics of actually making chips even faster.If you look at the speeds these devices work at, it's absolutely breathtaking. Desktop chips regularly do 5 GHz without exotic cooling solutions. If you do a crude calculation how far light travels in a vacuum between clock cycles, that's a little under 6 cm! To put that into ever more perspective, light travels about 74948 km, or 46571 miles in the blink of an eye.

author: medical-nerd
author_rank: Regular Contributor
timestamp: November 06, 2017, 11:30:04 pm
content: HiyaA couple of weeks ago I used a 3.5inch floppy drive (from my hoard of old pc parts) to load msdos 6.2 disks and turbo pascal 7.0 disks, all of which haven't been used for >15 years - all of which loaded successfully. I made the mistake of loading a floppy into a drive that didn't spin. After a quick dismantle I found why - one of my children must have squeezed a biscuit in years ago. After a wipe down the floppy worked in the working drive!! I also used a 270MB HD which hadn't been used since 1994, booted and still had my old pascal filesCheers

author: MK14
author_rank: Super Contributor
timestamp: November 06, 2017, 11:30:45 pm
content: Quote from: Mr. Scram on November 06, 2017, 11:23:12 pmI agree. Maybe slightly more performance than that, depending on how you measure it. The complications, are that core count, is beginning to increase (in general, such as AMD's Ryzen 8 core). So maybe ever increasing core count (at reasonable prices), will take over as the performance mark. From now on ?But multi core/thread software has a lot of catching up to do, and in many cases, that will be extremely difficult.=========================================================================Floppy disks became so crazily small (relatively, capacity wise). Hard disks, were massively increasing in capacity, to e.g. gigabytes. Yet the poor floppies, remained at 1.44 MB, seemingly forever.So you'd need 1,000,000+ floppies to backup your entire hard disk (I'm exaggerating again, but they soon became completely impracticable to backup hard disks. Assuming the hard disk was full of stuff).I remember there was talk of bigger (standard floppies) ones (ignoring zip drives and similar). But they never materialised and the things like zip drives and such, mostly remained a minority thing.Fortunately CDs and DVDs, took over. Somehow blurays, don't seem to have hit PCs, in a big way yet (from my own observations).

author: MK14
author_rank: Super Contributor
timestamp: November 06, 2017, 11:43:09 pm
content: Quote from: medical-nerd on November 06, 2017, 11:30:04 pmI sometimes worry that any older achieves of data I have (e.g. floppies), from ages ago, may become unreadable. You are giving me some positive thoughts, that they will still be readable.I know that I should really copy them onto (ideally multiple) modern media. But that is another one of those projects, that I have not got around to doing.

author: MK14
author_rank: Super Contributor
timestamp: November 06, 2017, 11:49:40 pm
content: Quote from: Ian.M on November 06, 2017, 10:52:24 pmThere was an amazing amount of technology, both electronic and mechanical. Put into those 3.5" floppies, of old. Yet they could be had, as little as £7 retail, brand new. I guess they were made in such absolutely huge quantities, that the price got knocked down, really low.Yet if I bought, just a similar stepper motor, from Farnell. It alone would probably be most of the £7's. Let alone all the other bits and pieces.Presumably the heads, were "expensive" in the technical sense. But the immense production volumes, must have meant big machines, could churn out so many millions of those heads. That the costs, were sent, way, way down.

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 07, 2017, 12:16:12 am
content: Quote from: MK14 on November 06, 2017, 11:49:40 pmThe magic of mass production is incredible, even for simpler objects. I can buy a complete hardwood stool, with perfect fit and finish, for considerably less than it would cost me to buy cheap spruce to make one myself. That isn't even hardwood from unsustainable sources, but the properly planted stuff. We're not even talking about tools, other materials and hours yet.It's also both funny and highly annoying that technologies that tend to be cheap in large numbers, are actually unbearably expensive when the numbers are small. The reverse doesn't seem to be quite as true, even though technologies that work on a small scale tend to be more expensive on larger scales than their mass production optimized brethren.

author: MK14
author_rank: Super Contributor
timestamp: November 07, 2017, 12:27:32 am
content: Quote from: Mr. Scram on November 07, 2017, 12:16:12 amI recently bought a USB to Midi (Music) conversion cable from amazon (third party sellers). I haven't tried it yet, but it got very good reviews and looks really good.It came in an A5 package, was neatly packed up. Comes with English information cardboard and a nice plastic (disposable) container. Has Din plugs, USB, LED(s) and presumably an MCU and electronics inside.All for £3.36 total, from (presumably) China.I bet it would cost me £3.36 (or nearly that amount), just to post it to my next door neighbour, in the UK.So, amazon sellers fees, postage from China to the UK for a small parcel, electronics, nice leads, various connectors, LEDs etc. MCU, all for just £3.36, CRAZY!I bet I could pay £3 or more, just for a USB lead, from a physical shop retailer.I'm confident it will work (I'll find out at Christmas, probably). But even if it doesn't (I'm 85% sure it will work), it was cheap enough to risk it.