I picked up a stand-alone word processor (missing cables & monitor) the other day and it wasn't until I opened it that I realized something that should have been obvious:
This is not a 3.5" floppy drive!
It's a Mitsumi Quick Disk! The kind that was adapted into the Nintendo Famicom disks. I should have remembered that Smith-Corona used these drives for some of their systems.
Anyway, this is a Smith Corona PWP 220.
On the back, it's got DB-9 (female) for display, DB-9 (male) for a printer, and a 12.6 volts AC power supply connection.
On the side, a power switch and a RJ-45 keyboard port. I have no keyboard, sadly.
Inside (which took forever to get in. it uses some weird torx bits that are set WAY down small holes, so it required a very specific screwdriver to get to) it's one big motherboard, partially shielded, and then the floppy drive. Which is very clearly not a 3.5"
The drive's so Mitsumi Quick Disk that it was made by Mitsumi. Who also made the motor.
It's labeled 1D01741N, which has no results on google.
Also, check out that 12-pin connector. Definitely not Shugart.
Wooo, my guess was right! The main CPU is a (bodged) Z08400: That's a Z80. One from the last week of 1990, apparently.
And a classic CRT controller: a Motorola 6845P.
And our firmware is here, on an AM27C256 EPROM. 32 entire kilobytes.
And it's yet another eprom soldered to the motherboard, argh.
They wouldn't have room for a socket here (because it's under the shield) but they could have shoved it over on the left, where there's no shielding, surely?
RAM is provided by this Sharp LH5160, an 8 kilobyte SRAM chip.
There's a big chip from Motorola that says 761060 SCQ38124PI01 ZQHAE9102
No results, but there's a reddit post speculating this is some kind of IO controller. Possibly this is a custom ASIC, I believe Motorola had a product line for making those, as a sort of proto-FPGA service
Now this is interesting: More storage! This is a Fujitsu MB834000A half-megabyte mask ROM.
That's a LOT of storage for such a little device! Maybe this thing has a whole complex OS on here? or spellcheck or something? I'm not really sure what they'd need so much storage for.
Next to it is a chip labeled iMP 9103CCD 786640. No results.
There's an AM7866 that's an ADC but I don't know why a wordprocessor would need one of those, so... I'm not sure what this is. My guess would be that it's some kind of serial control chip, maybe?
and placed near the keyboard connector is everyone's favorite microcontroller that's in literally everything, punch out another spot on your member's rewards card, it's an 8051!
A real Intel one from 1986, not even a second source or clone.
It's also got a beeper. A very big one. I'm guessing this fucker is LOUD.
The power section features an RS402L Bridge Rectifier.
Man they're only one transformer away from just having an AC-in. I'm guessing they only didn't have that for electrical compliance reasons
I don't have any easy way to power this (I don't have any 12.6 VAC power supplies on hand), plus I don't know what monitor standard that is (guessing monochrome DB-9, like MDA?), and I don't have a keyboard.
still, interesting machine.
Found an ebay listing for one.
https://www.ebay.com/itm/295124046576
The back of that monitor makes me think that yeah, it's an MDA monitor. Definitely not color.
Smith Corona PWP 220 Personal Word Processcor and printer | eBay
Find many great new & used options and get the best deals for Smith Corona PWP 220 Personal Word Processcor and printer at the best online prices at eBay! Free shipping for many products!
Hi I'm Smith Corona and my greatest love is recessed Torx Screws because I hate it when it's easy to disassemble things
Did one of my trademark High Quality Pinouts for the keyboard connector.
it seems it has a 4-bit or 5-bit interface. My guess is that it's a 4-bit IN and a 1-BIT OUT. Possibly just a shift buffer on the keyboard side, and the OUT is used to trigger it to read out another 4 bits?
thinking about emailing the person on ebay who has a whole system for sale for 120 OBO + 120$ shipping and seeing if they'll loan me the keyboard for long enough to figure out the protocol
DC power is provided by an RFP15P05... NOPE!
I thought this'd be a linear regulator but it turns out it's a power mosfet? huh
MC1489P: quad serial receiver
LM393N: dual voltage comparator
I missed two chips, NEC D41464C. 32 kilobytes of DRAM each, 4 bits, so 64 kilobytes in total.
So maybe that 8k of SRAM was a video buffer? 8K is plenty for a text-only buffer, even with attributes. (80x40 is 3,200 bytes, so 80x40x2 is only 6,400 bytes )
BUT NOW THE MOMENT OF TRUTH:
let's open up the drive and find out if it still has a belt
I'm gonna go with "not really"
decayed bits of belt still stuck to the motor.
RUBBER AND COMPUTERS DO NOT MIX
fun fact about mitsumi quick disks:
There is only one motor. and it's a simple DC motor, not a stepper motor.
How does it position the drive head? it's all cam-based! it just loops from beginning to end. Instead of sectors and tracks, the data is encoded as a spiral.
the rest of the belt is gooped onto this gear
there it is. check out that lovely spiral.
This rotates as the disk spins, just slower. The spiral shoves the head back and forth, causing the head to trace a spiral track on the disk surface
mm, 30 year old coagulated lubricant.
this probably isn't carcinogenic at all
using
@rechner 's trick of just putting more DC through the AC plug got it to turn on. Front light comes on, the display initializes, but nothing appears.
I'm guessing it's mad there's no keyboard attached
Finally got around to desoldering the EEPROM.
It's a font! and that's all!
and now I dumped the MB834000A and all I can see is a spellcheck/dictionary.
It's possible I'm only dumping half of it though
ok yeah re-dumped it and I've got some code now.
it's weirdly organized: it seems like they divided the ROM into blocks, and there's code at the beginning of each block, with dictionary/spellcheck at the end
@foone: Perhaps they arranged the address lines in some non-intuitive way when drawing the PCB. Does the code seem to be meaningful even if interpreted as blocks?
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