Gregory's ServerThere'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?
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22 comments
 Assorted power regulation/charging circuitry that I'm not going to go into. 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! Next to it we've got a P25Q40H half-megabyte serial flash chip. This is presumably used to store configuration info for the RTD2660. 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. The keyboard is a rubber membrane onto the PCB, like a remote control. It's functional but feels pretty crap. 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. The other connector is 12 pins: 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 Games included: there's also the SBVGM audio player, which includes "Funky Stars" and the whole soundtrack of PlanetX3  @foone Hell, yeah! Gotta include the Hybrid song, even when you don't have a device capable of playing the original sampled tracker version! @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! @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).  @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.  @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.🔧 ) |
A YAC512-M. This is a DAC used by the OPL3 to create the analog output of the audio chip.