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Foone🏳️‍⚧️

Chip info here:
Also, I was wrong. Apparently it goes up to 64 megabytes of RAM:

dmp.com.tw/app/webcamera/pdf/m

31 comments
Foone🏳️‍⚧️

Next to the CPU, we've got four DRAM chips. AMIC A420616AS-50F, 2-megabyte chips.
So we're looking at 8 megabytes.

Foone🏳️‍⚧️

Then we've got our VGA chip: A Chips&Technologies 65535.
This is a fully integrated chip with built in CRT controller/flat panel support, RAMDAC, and and clocks.
It supports up to 1280x1024 resolution with enough VRAM, or 640x480 16bpp truecolor.

Foone🏳️‍⚧️

For VRAM, a Sharp LH6A4260K-60, which I'm pretty sure is a 512 kilobyte chip, but I can't be sure.

Foone🏳️‍⚧️

The really surprising chip is this, a Yamaha OPL3 YMF262-M...
Yeah, this thing has real OPL3 sound. Assuming this chip is genuine, of course.

Foone🏳️‍⚧️

There's two SST39SF512 half-megabyte flash chips.
The left is labeled VIDEO and the right is labeled BIOS.

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

The last interesting thing about the top of the PCB is that there's another speaker, labeled SP1.
There's two stereo speakers as well, so I suspect this is just used for PC Speaker, and was easier than merging the audio in with those other speakers

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

So here's another blurry navigation-picture for the other side of the PCB. The interesting thing here is that they've got the keyboard on a separate PCB.

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

So over by the USB port, we've got a CH375B.
This is an 8-bit IO chip for USB, specifically for storage.
(it's also an 8051-based core! there's always an 8051)

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

There's three 74HC139s, which are dual 2-to-4 line decoders.

This maybe is used for wiring up one of the expansion ports to the ISA bus?

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

A YAC512-M. This is a DAC used by the OPL3 to create the analog output of the audio chip.

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

A PAM8403 three-watt class-D stereo audio amplifier.

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

Assorted power regulation/charging circuitry that I'm not going to go into.

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

though I do want to show off this amazing bodge job.

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

So the keyboard PCB is also the display converter PCB. It stars a Realtek RTD2660, which is a standard video controller. It takes in analog video and drives LVDS displays with it. It's an all-in-one chip that's used on a bunch of cheap monitors, and it's also an 8051!

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

Next to it we've got a P25Q40H half-megabyte serial flash chip. This is presumably used to store configuration info for the RTD2660.

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

The other chip on the keyboard/video board is an HM82C42. I can't find any info on this specific version, but it's almost certainly an Intel MCS-48 acting as a PS/2 keyboard controller.

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

The keyboard is a rubber membrane onto the PCB, like a remote control. It's functional but feels pretty crap.

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

that large connector on the side is called "ISA" on the PCB.

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

It's a 60 pin connector. 8-bit ISA is 62 pins, 16-bit ISA is 98 pins.

So if they just merged some grounds, 60-pins is totally doable.

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

The other connector is 12 pins:
This one is PS/2 and VGA. An adapter is included with the device.

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

Storage is on a 2 gigabyte CF card. It's got Dos 7.1, Windows 95, and a few games pre-installed on it, plus a driver for the CH375 USB storage chip

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

Games included:
Doom, Wolf3d, XianJian QiXia Zhuan (aka Chinese Paladin), Tyrian, Raptor: Call of the Shadows, and Uncharted Waters: New Horizons
Daikoukai Jidai II

Foone🏳️‍⚧️ replied to Foone🏳️‍⚧️

there's also the SBVGM audio player, which includes "Funky Stars" and the whole soundtrack of PlanetX3

Anatoly Shashkin💾 replied to Foone🏳️‍⚧️

@foone Hell, yeah! Gotta include the Hybrid song, even when you don't have a device capable of playing the original sampled tracker version!

Anatoly Shashkin💾 replied to Anatoly

@foone Wait! What the fuck! I don't actually have an OPL version of the Hybrid song. Yo! Can we get that "Funky Stars" file!

Lion abt not making pride puns replied to Foone🏳️‍⚧️

@foone Does it *have* any digital audio? Because I've only seen literally the OPL3, so hypothesized it was synth-only (time to dust off the MIDI sound efffects that I think fraggle might have uncovered in DOOM, or at least boosted).

DrYak replied to Lion abt not making pride puns

@LionsPhil no, unless you bitbang some PWM out of the PC Speaker (like lots DOS of MOD-trackers, and some games - e.g. RealSound - used to do). But that will sound very bad on a piezo.

Also: this is a 386*SX* (16bit, no cache) so Doom is already stretching it.

DrYak replied to DrYak

@dryak (or, you could also try volume-modulating on the FM chip. But in my fuzzy memory from back in days, it's a bit more complicated on an OPL3)

coffe☕ replied to Foone🏳️‍⚧️

@foone i know that this is the absolutely worst thing to ask, but after your excellent teardown there is only one question that's unasked: will it blend!!!? 👌 (Grats and thanks for a nicely done teardown.🔧 )

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