foone Profile picture
10 Jun, 38 tweets, 9 min read
Today I may get to document a previously unknown type of floppy disk.
It's a good day to be a Foone
Ever seen one of these before?
here it is next to an 8" (NOT a 5.25"!) disk
this is officially a Huge Motherfucker of a disk.
it's apparently haɾd sectored.
Interestingly the jacket isn't vinyl or plastic: it's cardboard.
Bigger than a laserdisc.
Here's the fun part: I didn't just get one disk. I got a whole custom-made carrying case of Goodies relating to it.
this includes about 7 of them in good condition and then about 12 of them that are water damaged
But some of the damaged ones have labels.
"Sound Ideas"
EIS: Education & Information Systems Inc
Chinese Language Drill 11-March-1985.
which is a lot of interesting info and would be a great place to start researching...

if I didn't also have a drive. BEHOLD, THE INSTAVOX!
So here's the front panel. We've got headphones, microphone, volume & mic levels, power. Plus a big lever to let you take out the disk, because THIS WHOLE THING is one very wide drive.
Around the back, we've got a DB-25 "Data" connector, a power connector, and RCA jacks for Line Output/Input/Speaker.
And the little plate says it's an EIS Instavox, Model RA-12A RRC1, Serial number 42602.
So there aren't many results on the internet for this thing and what few there are, are academic papers I can't get access to.
But they all seem to be about speech therapy/voice training.
My vague understanding of how this thing works is that it's a partially or fully analog audio medium, and is used to record and playback audio clips.
And I think we're missing a piece here:
Where are the controls for this?
Either there was an external controller that I'm missing, or to use this thing you had to hook it up to a computer and the computer would control it.
I double checked the carrying case and found this.
Those are the pins for ground, TX, RX, and Ground again.
This thing is a RS232 serial device.
man this thing is a lot.
So I opened it up!
This is what I was warned about before buying it: there is a belt that is just missing.
That belt turns a wheel under the disk, and this solenoid pushes down another wheel so that the disk is grabbed between them, and will rotate.
So instead of rotating from the center spindle, this disk apparently is rotated from the edge!
That's what this cut-out in the disk is for. It's somewhere for the wheel to grab it.
this disk that was in the unit didn't do that well. Something, a belt or some cushioning foam, totally disintegrated all over it.
The thing seems to be mainly 74-series logic, but there may be an MCU somewhere.
This big chip isn't a microcontroller: It's a WD TD1865P UART.
and something has gunked all over this thing.
This bit is really interesting. So the drive head is mounted on this bit that can slide back and forth, and there's some kind of optical encoder here to let it know what track it's over
You can see here it's got binary code on a sort of transparent plastic or glass
there's a very messy baud rate selector on here. Apparently it's set to 4800
So under the main smarts board is this board, which has three of these LM3900Ns, which are QUADRUPLE NORTON OPERATIONAL AMPLIFIERS.
I don't know why they're Norton. Emperor Norton, I assume.
Backside of the board: not much, just a few bodges.
back of the modem board: not much, just some odd decolorization that I imagine has something to do with how it was made in the Long Agos or the water damage it apparently suffered in the meantime
I figured out what the goop was: there was felt protective stuff on the top of, which has completely disintegrated
The covered up chip (with a big heatsink and thermal goop) is an LM384N, which is an audio power amplifier IC
So yeah I don't think there's a microcontroller in this thing. I think it just must take the serial input and then set up control lines from that, from some buffer. 70s!
I opened the bottom, which was a mistake.
Here it is cleaned off a bit.
Some more switches, some power bits, another fucking solenoid (HOW MANY DO YOU NEED MAN), and a motor.
but yeah the bottom was full of this foam which is disintegrating and moldy and I hate it
anyway I need to go clean my hands a lot and handle some other stuff. I'll get back and do more reversing on this thing and more repairing.
in the mean time it'd be nifty if you could send me a dollar or two on ko-fi if you liked this. This thing wasn't cheap and I'm slightly broke.

• • •

Missing some Tweet in this thread? You can try to force a refresh

Keep Current with foone

foone Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!


Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @Foone

12 Jun
Doing more documentation on the Instavox PCBs. This is the Modem Board. Image
I already identified the big chip as a WD TR1865P-00, which is a UART.
-00 means the clock maxes out at 1mhz. I think the TR1865 (vs TR1863) just means it has internal pull-ups on all inputs. Image
Read 77 tweets
12 Jun
I'm not interested in the news about more Castlevania shows because all the best Castlevania story happened right here.

Here's a version filmed with pixels and not potates
Read 7 tweets
12 Jun
The worst thing about modern adaptations/remakes is when they're explicitly not allowed to show or involve some old element because the rights are different.
Like I listened to a thing about She-Ra which said they can't use any He-Man villains or He-Man himself
Despite the original She-Ra starting as a he-man spinoff.

And that's bullshit
Yeah there's a new he-man cartoon in the works and they don't want to have rights complications and confuse the audience but have you considered who cares?
Read 19 tweets
12 Jun
The best thing about modern Tumblr is that there will be a post that's a video of some big strong lady showing odd how she can lift a thousand pounds or she'll be showing how good she is at swordfighting or archery or something and I'm like say the line, say the line! Image
And then someone will reblog with this image Image
And I cheer. Fuck yeah you funky wlws.
Read 13 tweets
11 Jun
Someone should make a compilation of people who did unaware playthroughs of The Outer Wilds and their reaction to what happens about 20 minutes into the game.
This thread will have spoilers when I go and do that
But for now, if you haven't played it, don't look it up. Just go play it. It's an amazing game of space exploration in a small scale
First Materwelonz. They didn't die before. My favorite part is "wait, what's that noise?"
Read 34 tweets
11 Jun
That conspiracy about the vac cine making you magnetic is just the best. I love it, because it's just so left field and nonsense
BTW if you take too many Tylenol/paracetamol it will make your body emit radio waves in the 93.4 mhz range which may interfere with your reception of your favorite heavy metal FM radio station
Be careful doing electrical work if you're on antibiotics because they can cause your body's resistance to drop, which may increase the chance of a dangerous shock
Read 45 tweets

Did Thread Reader help you today?

Support us! We are indie developers!

This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal Become our Patreon

Thank you for your support!

Follow Us on Twitter!