foone

foone, 11 months ago

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

foone, 11 months ago

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

foone, 11 months ago

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

foone, 11 months ago

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, 11 months ago

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, 11 months ago

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

foone, 11 months ago

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, 11 months ago

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

foone, 11 months ago

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

https://www.dmp.com.tw/app/webcamera/pdf/m6117d.pdf

foone, 11 months ago

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, 11 months ago

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, 11 months ago

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, 11 months ago

first off, lemme get the spoilers out of the way: It's real, it runs DOS/Windows 95, and it can run Doom (badly) and VGAPride.

image/png
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foone, 11 months ago

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

foone, 11 months ago

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, 11 months ago

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

foone, 11 months ago

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

foone, 11 months ago

So the M6117D is a 386SX-compatible system on a chip.
It's a static 386SX Core (apparently licensed from Intel?) plus ram controller, peripheral controllers, IDE support. It runs at 25-40mhz, and up to 16 megabytes of RAM

foone, 11 months ago

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, 11 months ago

First off, the CPU. This is surprising! It's an DM&P ALi M6117D.
This is a modified version of the chip made by ALi/ULi, licensed to DM&P. ALi's chip division was bought by Nvidia in 2006.

foone, 11 months ago

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

image/png

foone, 11 months ago

It's easy to open (this image came out blurry, but I'm just using it for navgiation)

We've got two terminal connectors on the left, plus a 3.5mm audio jack. The right has a USB port and a barrel jack power connector.

foone, 11 months ago

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, 11 months ago

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, 11 months ago

@BradRubenstein nice!