We connect an 8″ floppy drive to a PC, learn the 11 ways they are different from standard PC floppies, and even design an adapter and make it available for all on Tindie.
Chapters:
00:00 Intro
01:20 My 8″ drives come from an HP 9895
02:37 The IBM 8″ floppy and its media
06:03 Antoine’s 8″ floppy adapter
07:06 Booting my PC from the 8″ floppy
08:24 8″ drive restoration and bring up
11:08 Making the prototype cable adapter
20:16 The 11 quirks of 8″ floppies
20:52 Single sided vs. double sided
21:48 Write protect works reverse
22:52 Four address wires!
24:56 Head load signal
25:41 Door lock signal
26:38 Disk ready vs. disk change
28:02 Track 43 current control
28:37 Pull up resistors
29:28 500kHz data rate
30:07 FM modulation support
30:49 ImageDisk and Omnidisk setup for 77 tracks
32:52 Formatting an 8″ Floppy
34:07 Using the floppy with Windows
35:25 Playing Donkey Kong from the 8″ diskette
Antoine’s 8 inch floppy adapter on Tindie: https://www.tindie.com/products/siliconinsider/8-floppy-disk-interface-50-pin-to-34-pin-adapter/
Adrian’s Digital Basement video on the 8″ floppy: https://youtu.be/TfEzjcG_0gs
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I remember when someone donated a S100 development system to our school in the early 80s; there was little chance of us ever getting it running, so a few of us nerds shared the spoils; I ended up with the Persci dual 8" disk drive (277 or 290, not sure which). Sadly very little remains of the drive except for some rather nice DC motor / gearboxes which operated the disk clamps.
I think most people are unaware that the 1.2 MB 5.25" floppy format was stolen wholesale from the 8" disk format, and it is possible to fool hardware looking for one by giving it the other. Not terribly helpful when you have actual 8" disks to read, but it could be useful for those who just want to get something to work, and are willing to write their own disks. I bet there are a lot more working 1.2 MB 5.25" drives still around than working 8" drives.
I find it humorous that IBM's brilliant plan to modernize the PC/AT was to steal a floppy disk format from a decade prior, just make it smaller, and it almost worked. They just got leapfrogged by the 3.5" format.
Check out MS-DOS CONFIG.SYS loadable DRIVER.SYS. I can't remember when it came into being. But it allows
you to configure/set-up an oddball floppy drive. I believe it started out for 720k 3.5"ers.
format b: /T:77
Nice video btw!
You shouldn't complain about the 8 inch floppy being inconvenient. They were so much faster and more convenient than paper tape, and you could put so much more data on them!
Is that Master Ken in the background???
I'm 56 years old. Oh, what I'd give to upgrade my 5.25" floppy to an 8" floppy…
"It's [the 3.5" disk is] not even floppy, so it doesn't count." Oops, not true. They were so named because of the actual disk, not the jacket. That's why Amstrad disks, Bernoulli disks, Zip disks, and the few others with hard jackets are still floppy disks.
"Read-only"? Then how would it be written to the first time? Did you mean "end-user-read-only" instead?
"4 different types of floppies…"
* …of that physical size, that is.
"This has only one side…"
…until you punch whatever notch or hole that would make the drive recognize it when you flip it over.
Wow, that version of Donkey Kong looks just like the arcade one, at least the best I can tell!
"Flexible-disk memory…." Ha, it's odd that anyone would call it "memory" even though it's actually storage. That's like calling a flash storage card a "memory card." Oops on them.
Shoot, how did that one part inside get bent?
(Ha, I don't expect you to know that.)
"AC motor that's always on" (when the computer is)? I see that you mentioned the head-load/unload solenoid on that older drive. Why would there not be some sort of simple transistor-to-relay method of controlling that AC motor to turn off and back on?
Haha, oops, at first you had a second #1 instead of the #11.
So if the PC drives are jumpered to B by default but they are cable-select via the twist, then why even have the jumper?
So if I understand right, you just told the drive to forget the lock, because it's not necessary for proper operation by a couple guys who are NOT idi…(YT cens. maybe)…ots?
"FM modulation"? What: "frequency modulation modulation"? There can't be such a thing as that.
"PC disks have either 40 or 80 tracks…"
* …the specific ones you're comparing against these, that is.
"You can run a PC off an 8" disk"? Yeah, we knew that. But now we want to see you run the PC ON the 8" disk. Oh, I think you already did that. Congrats on getting that to work!
Watching that video reminds me that I still hope some time I find the spare time for my pet project which is that nifty little computer I used in the early 1980s for paid software development:
An SWTPc system based on the 6809 μP with a stripped down Unix V6 rewrite as OS, called UniFLEX. It's sitting right here in the corner … and it of course has an 8" floppy drive …
Any recommendations what to look for BEFORE I try to apply power for the first time after maybe 25…30 years?
Would be interesting if you can do a video on floppy-drive-interface tape drives some time. Info on how those worked seems to be some of the rarer info on floppy drive connections.
Ahh, this brings back memories. I spent most of my early career working on and with CDC equipment. The CDC floppy was the first soft media drive I ever worked with. I had to write some drivers for it back in the dark ages.
0:14 The case is hard. THE DISK INSIDE is floppy!!!
5:40 SASI?
Al Shugart also founded Seagate – who is still around and dominant today. They also created SASI – Shugart Associates Systems Interface – which was stadardized and became SCSI used by Apple, Sun and many Minicomputer and Mainframe suppliers. It took the workload of managing the drive off of the main system and turned it into a "block transfer" device. This greatly simplified the drivers AND allowed the peripheral to change to tape, RAID or whatever on its own with the host not having to spin up yet another driver. Seagate was also the first to introduce optical connects between peripherals. As SCSI got faster and wider the connector and cabling became unwieldy. In came the low power laser with cheap fiber to carry the load. The prices dropped so dramatically that it drove down fiber networking. Its why you can have cheap mega-datacenters today. If there isn't a Shugart Prize, there should be.
I wanted to also chime in – the floppy (flexible) media and format thereon was quite unique for different systems. Same physical "blank" could be soft sectored (one hole per revolution) that indicated the start of sector zero. For those you had to write the entire track. (Read/Modify/Write) Some were hard sectored – wherein every sector had its own hole and the hardware counted them to read/write the specific one. No need to read the whole track. Every company had its own track definition. An Apple disk had a different format then a Xerox or IBM. I think the most interesting variant was the Apple LISA floppy (remember Hard Drives (from Seagate) were just coming out when the LISA was introduced). The LISA floppy had two slots on oppsite sides. This allowed it to read in the first half of the rotation and write as the media spun around to the other half. No one else ever did this to my understanding as it made for a much more expensive drive but as the LISA was a virtual memory OS it was necessary. Hard drives changed it all of course. (A 5 MEGABYTE drive in 1983 cost $5000 and we wondered WHY anyone needed that much storage. Hell OS/2 followed by Windows NT shipped in a huge box with 56 floppies! ROM was hugely expensive until FLASH and even that was costly until the MP3 revolution and SmartPhones starting with the Qualcomm QPhone and Microsoft Windows CE Smartphone and Blackberry which predated all Apple by quite a while. )
AES word processors in Canada used 8in hard sectored floppy drives
Thanks for providing all the details on 8" floppies! I had one on a CompuPro many many years ago.
I remember maybe 10-15 years ago reading about how most, if not all American ICBM silos use outdated technology, they were especially keen on showing how they still use 8in floppy drives. And here we always make fun of communist states (DPRK, RF, PRC) for using outdated, soviet technology. I dunno if they ever updated or how prevelant the use of such old systems was at that time, it was a while back. But certainly not long enough ago to warrant using 8in floppies for technology that can destroy the world multiple times over.