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This is pretty neat. Side-by-side comparison of the initial tank-in-a-crate scene between MAME and footage of real hardware captured by Uncle Phil. The very slightly visible inset in the top part of the door, and the way the point on the bottom part of the door aligns with the credits readout are great reference points. smile

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Since I just realized I haven't actually posted a link in this here thread, and only the shoutbox, I did an extensive write-up on the path to getting Polygonet Commanders emulated. Feel free to have a read: http://blog.polygonal-moogle.com/mame/poly-go-not/

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I started working on turning the PS/2 skeleton driver into something more fleshed out. Modified AT_MB to be a PS2_MB, turned the DMA controller into a PS/2 DMA controller device, hooked up the keyboard controller and planar VGA, got a skeleton MCA bus going, and a day and a half later it gets more than halfway through POST (checkpoint $4C of $6E) before the BIOS gives up, beeps, and throws up a timer error.

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NICE!

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Chipping away at the PS/2 hardware still. I'm targeting the Model 80 planar because that's what I have here next to me. I'm working on getting the planar devices working before I tackle MCA in full. So far I've added a generic PS/2 PIT (the chipset features a fourth timer channel that triggers an NMI if IRQ0 isn't being serviced), the extended NVRAM, and started working on the PS/2 DMA controller. They're implemented on a ps2_mb_device like the AT motherboard. It now gets into BASIC from a hard reset with no tests bypassed or anything, but throws up a ton of POST errors.

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It's interesting that IBM customized the PIT for the PS/2 series. The Model 25 and Model 30 actually use a standard 8253 PIT, but those are already known to be a bit different from the rest of the line, being 8086-based systems. (Model 30 also uses a National MM58167 RTC, which also shows up in a few XT clones.)

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The PS/2-specific components are inside two giant ASICs - there’s a DMA controller with extended functionality compared to the AT and an I/O chip hooked up to just about every signal on the board. On the other hand the UART, dual PICs, and FDC are commodity parts. From my understanding the 60, 80, and 90 are similar and share most components.

I’ve got the serial ports and floppy controller hooked up enough that the POST stopped complaining but it’s not booting from disks yet. The system recognizes the drives but no data is getting through, just seek errors. I’ll break out my 386 assembler and whip up some test programs to figure out what’s going on, I guess.

Last edited by Luigi30; 07/02/22 08:46 AM.
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Is the floppy controller shared with any of the other PC or PC-adjunct drivers in MAME? I have a vague recollection of the floppy handling in MAME's PC driver being cursed as shit, with "randomly not booting MS-DOS install floppies" being the tip of the iceberg, so I'd like to think the efforts you're putting in to debug the PS/2's floppy controller might help other drivers as well.

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crazyc can correct me, but I don't know of any serious issues with the PC floppy handling right now. The uPD765 is among the best-exercised components in MAME at this point.

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Yeah, it’s one of the later 765s. I think the problem is with my DMA handling, not the FDC.

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