Alice Averlong🏳️‍⚧️Dec 19, 2022
check out this wackiness in a removable hard drive sled inside a TASCAM MMR-8: It has a key lock, but the key lock doesn't lock the door, as you'd expect. Instead the lock is just a switch, and it communicates back with some board, which controls a solenoid to unlock the door. Now that's some paranoid over-design!
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
heh. The manual lists the approved hard drives for use with it.
I guess none of the letters in "SCSI" are "standard"!
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022

also the weird one in that list is the Nikon thing with the asterisk.
It turns out it's a 2.5gb magneto-optical drive that I think was only released in japan?

https://item.rakuten.co.jp/waysas/10015260/?scid=s_kwa_pla_unpaid_211514

Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
Anyway, this is the TASCAM MMR-8.
Sadly it's not as useful (for me) as I was hoping: it has a lot of video support, but it's not really for doing video: it's for syncing audio TO video. This is specifically an audio device, not a video device. Whoops.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
fun fact: it turns out that inside it's built on a Socket 7 motherboard. From ASUS!
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
Also apparently the OS is stored on a Quantum Fireball IDE drive.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
So the motherboard is an ASUS TX97. That's based on an Intel 430TX chipset, and can run Pentiums throughs AMD-K6.
It supports up to 256mb of RAM in 168-pin SDRAM slots. 3 ISA slots, 3 PCI slots, and one combination PCI/MediaBus/ISA slot.
Built in IDE, can be powered by AT or ATX power supplies.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
And it turns out that CPU is a Pentium 133mhz, SY022.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
Let's go through the boards.
The smallest one is this MMR Biphase Option (BOB), ASSY 70303.
Seems to have a bunch of RJ-?? plugs.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
Then a Symbios SYM8600SP SCSI board. Seems to be pretty standard, this is probably just an off the shelf component.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
The first big custom board is this TimeLine Sync2 ASSY 70386.
A bunch of FPGA chips, custom ASICs, and EEPROMs.
It's 16-bit ISA, but it seems to talk to other boards through that big locking IDC connector on the top left, so that probably doesn't matter much.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
Then the MMR UIB, ASSY 70302.
More FPGAs, ASICs, and EEPROMs.
They integrated the serial port from the motherboard into this card, it seems.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
Then the 70384 DIO.
Digital I/O, I suspect.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
It's got 4 of these CS8411-CS digital audio receivers, and then 4 of these CS8401-CS digital audio transmitters.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
And four of these IDT7132SA20J 2 kilobyte dual-ported static-ram chips. Probably for audio buffering/processing at super-low latency
Show threadAlice Averlong🏳️‍⚧️
Then another of the same board, but this one is missing the receiver/transmitter chips. It's just got the RAM and FPGA.
Dec 19, 2022 at 9:01pmWeb
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
Then the final board is a Timeline PRX ASSY 70383.
More SRAMs and lattice chips, and a PLX PCI9060 bus controller.
So I suspect that many-pins backplane they use to connect all the boards may be a second PCI bus.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
It's also got a Motorola DSP56002PV80, a 24-bit DSP.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
The front-panel display is a Optrex DMC-2026I display. 20x20 characters, each character being 5x8 pixels. This variant has a backlight, and it's built on the standard Hitachi HD44780 chip.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022

The front panel is communicated with through this MMR FP/UIB Interface, Assy 70301.

It's just a bunch of caps and resistors?

Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
and it's got three 32mb SDRAMs.
So 96mb in total. That's a bunch for a Pentium 1!
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
So it's got a separate power supply inside the case, plugged into a splitter on the power button line. (which, on an AT system, carries the full AC wall voltage)
It provides ±18v at half an amp.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
Those power these two boards (with room for a third, missing on this model)
This one is the MMR Input Converter, ASSY 70395. 8-channels.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
And an MMR Output Converter, ASSY 70372.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
And the floppy drive is a TEAC FD-235HF, one of the most common models of 3.5" floppy disk drives.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022

The back panel has two PCBs.
The top one is a Parallel Remote board, ASSY 70374

It's got 4 of these UCN6821A 8-channel line drivers.

Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
Then the bottom board is the MMR Rear Panel, ASSY 70389.
Left to right, we've got Transport, Editor, two Lynx ports, Timecode Out/In, MIDI thru/out/in, video out/in, and word clock out/in.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
The power supply is a US Power SP2-4200F, a 200 watt AT supply.
But modified to have a different connector for the front power switch, so it can be branched off to the other power supply.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
So the front panel. There's three PCBs.
The big one is the 8 TRK FP-70311, which the other two little ones connect to.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
No chips on the other side. Just a bunch of buttons and LEDs. Interesting there's some spots for buttons that aren't present here.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
Doesn't seem to be any smarts on the board. Another of those UCN 5821A 8-channel drivers, and 5 Maxim MAX7219CWG LED drivers
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
Other two boards:
first an MMR Headphone Monitor, Assy 70396
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
and the MMR Transport SW, ASSY 70392.
I think these are combination buttons/lights.
Show threadAlice Averlong🏳️‍⚧️Dec 19, 2022
So yeah. That's the box! I'll plug in my archive box and try to dump the drive later.
Show threadAlice Averlong🏳️‍⚧️Dec 21, 2022
I lit up some of the buttons using a bench power supply. Nice glow! I wonder if they're incandescent?
Show threadAlice Averlong🏳️‍⚧️Dec 23, 2022

okay I dumped the hard drive

it's DOS 6.22

was not expecting that.

Show thread[zaphod@::1]#Dec 21, 2022
@foone measure consumption?
Show thread joDec 21, 2022
@foone neon maybe?
Show threadSᴘᴀᴄᴇMᴏᴜsᴇDec 21, 2022
@foone ok i must confess i do not know what "REH" can mean if not "REC"
Show threadlizard appreciatorDec 21, 2022
@foone any electrics can be incandescent, for a while
Show threadMae Dean Dec 21, 2022
@foone it’s incandescent… with RAGE.
Show threadAnte Vukorepa Dec 22, 2022
@foone What does the REHord button do?
Show threadBill OwensDec 22, 2022
@foone Great opportunity to use your pocket spectroscope!
Show threadDaniel SvindsethDec 20, 2022

@foone they look, so... tactile...

Must.. press

Show threadBen LambDec 20, 2022
@foone too bad this didn't do what you want it to do, otherwise you could swap out that old mobo for something modern but that can otherwise support ISA, like an industrial system or something. You know, just for laughs.
Show threadAeáro, a SeaWyrm Dec 19, 2022

@foone

 Reh!

Show threadAmelyuelDec 19, 2022
@foone REH is for Rehearse?
Show threadsylvie and fiora nightshadeDec 19, 2022
@foone as a dragon i enjoy the REH button
Show threadtibiDec 19, 2022
@foone they look so... sugary
Show thread//AscorDec 19, 2022
@foone We've lost our way and need to return to whatever made us design buttons like that. They're gorgeous.
Show threadSpeakerToManagersDec 21, 2022
@Ascor @foone
Wait til you see them light up! I’ve built instrumentation with those buttons, and they really do add to the feeling of _Science!_.
Show threadElectricCrowbarDec 20, 2022
@foone ughhh I want these buttons
Show thread[zaphod@::1]#Dec 19, 2022
@foone foone, you should rename yourself to "Hardware porn"!
Show threadNeilDec 19, 2022
@foone Heh, whenever I see boards with buttons that are normally inaccessible or not populated, I "press" them to see if anything happens!
Show threadBeldantazarDec 19, 2022
@foone i'm going to assume you are holding that very close to the camera, because otherwise that's a colossal molex.
Show threadMike Kasprzak 🦖Dec 19, 2022
@foone Is that a trick of the camera, or is that connector *REALLY FREAKING HUGE*?
Show threadAlice Averlong🏳️‍⚧️Dec 20, 2022
@mike a little of both. It's quite large, but I am pointing it right at the camera
Show threadMomoDec 19, 2022
@foone
Checked by Rheinisch Westphälischer Tüv. Nice! 😅
Show threadporpyDec 19, 2022
@foone seeing your electronics photos makes us bird site refugees feel at home here. 👍
Show threadGraham Sutherland / PolynomialDec 19, 2022
@foone huh, I actually expected something beefier from a system this large and of this age, especially on the positive rail. the bipolar supplies make total sense, of course. is there a separate switching stage to derive logic Vcc/Vdd, or is it all linear?
Show thread1 Off By 1Dec 19, 2022
@foone I was thinking "Huh, that's similar to my current workstation 🤨" and then I remembered there's a diff between mb and gb
Show threadThick Judge JudyDec 19, 2022
@foone this brings back memories
Show threadAnthony, of courseDec 19, 2022
@foone my K5-PR166 had 96MB before it was retired for a Thunderbird Athlon
Show threadGraham Sutherland / PolynomialDec 19, 2022
@foone Hmm, I can't tell if those are AC coupling caps and termination resistors, or if this is a big bank of RC low pass filters.
Show thread48kRAMDec 19, 2022
@gsuberland @foone Probably EMI filtering. Thia was likely made for a film or TV studio where EMI mattered a lot. Also I wonder if those aren't resistors but actually ferrites.
Show threadGraham Sutherland / PolynomialDec 19, 2022
@48kRAM @foone oh right they say B not R, should've put my glasses on. basically a Pi filter then.
Show thread48kRAMDec 19, 2022
@gsuberland @foone That would be my guess too
Show threadGraham Sutherland / PolynomialDec 19, 2022
@48kRAM @foone given the layout, I actually wonder whether this is a case of poor decoupling & referencing on the far side causing conducted emissions back through the IOs, which they've tried to remedy with this filter bank. with the data rates involved and this era of silicon the Tr/Tf should be low enough not to be a considerable worry in terms of transmission line effects; the lines are probably lumped elements for all intents and purposes.
Show threadGraham Sutherland / PolynomialDec 19, 2022
@48kRAM @foone (it could also be related to a mismatch in gate drive strength vs the termination impedance... idk if these DSP chips typically have IO drive strength attenuation options)
Show threadGraham Sutherland / PolynomialDec 19, 2022

@48kRAM @foone uh, s/low enough/long enough/

long Tr/Tf → smaller dV/dt → smaller dI/dt at a given impedance → fewer transmission line effects from high frequency currents.

Show threadShinigamiDad 死Dec 19, 2022
@foone I love the soldered wire fix for a bad trace! :)