x86 emulator running itself as a testsuite?

Posted on 2020-01-31, 23:36

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by superfury

in PC Emulation

in PC Emulation

Would an x86 emulator running a copy of itself inside itself (e.g. UniPCemu running Windows running UniPCemu or Bochs running Windows running Bochs) count as a proper CPU emulation test? Or would it not verify anything? Of course I'm not counting the fact that emulation slows down for each level …

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Re: Windows NT 4 weird behaviour on track boundary read sectors?

Posted on 2020-01-31, 14:38

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by superfury

in PC Emulation

in PC Emulation

OK. Just tried NT 3.51 build 3.51.1057.1. It crashes in exactly the same way as NT4 does(with exactly the same error message and error codes)?

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Re: Windows NT 4 weird behaviour on track boundary read sectors?

Posted on 2020-01-31, 13:55

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by superfury

in PC Emulation

in PC Emulation

Hmmmm... When looking at trying to get ATAPI.SYS working on NT 3.1 to install NT 4 from the CD-ROM drive(from the NT 3.1 OS itself with ATAPI CD-ROM support), I keep getting the error screen during setup: https://www.betaarchive.com/forum/viewtopic.php?f=61&t=36255 It's the same as Condor.07's final …

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Re: Windows NT 4 weird behaviour on track boundary read sectors?

Posted on 2020-01-30, 18:22

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by superfury

in PC Emulation

in PC Emulation

Hmmm... After those last changes, rewriting said floppy disks using WINNT.EXE /ox and rebooting said disks, after Windows NT 4 starts it's kernel, I actually see it addressing the floppy disk with EOT=18(12h) a few times after loading the kernel? So perhaps that's an issue with the BIOS in some …

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Re: Windows NT 4 weird behaviour on track boundary read sectors?

Posted on 2020-01-30, 16:29

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by superfury

in PC Emulation

in PC Emulation

I've now modified it to only obey the field when in non-DMA mode, but in DMA mode it assumes the EOT by the drive geometry(it's SPT setting to be exact), This is wrong. The controller has no idea about the disk geometry except what is loaded into the eot field. If it's setting eot to 15 then it …

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Re: Windows NT 4 weird behaviour on track boundary read sectors?

Posted on 2020-01-30, 16:26

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by superfury

in PC Emulation

in PC Emulation

Hmmm... Linux's floppy driver sheds some more light: https://github.com/torvalds/linux/blob/master/drivers/block/floppy.c /* work around a bug in pseudo DMA * (on some FDCs) pseudo DMA does not stop when the CPU stops * sending data. Hence we need a different way to signal the * transfer length: We …

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Re: Windows NT 4 weird behaviour on track boundary read sectors?

Posted on 2020-01-30, 08:04

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by superfury

in PC Emulation

in PC Emulation

Weird that NT4 seems to set the max sector number/track size field to 0xF, while it should be ox12 instead, according to e.g. the osdev documentation(for 18 SPT)? I've now modified it to only obey the field when in non-DMA mode, but in DMA mode it assumes the EOT by the drive geometry(it's SPT …

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Re: Windows NT 4 weird behaviour on track boundary read sectors?

Posted on 2020-01-29, 19:47

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by superfury

in PC Emulation

in PC Emulation

Hmmmm... So looking at the booting process of Windows NT 4's boot disk, it sets the EOT fields to 0xF, so limiting it to sector 15 within the track. That causes issues with the way the FDC handles it's maximum sector before switching heads. So I've changed it back to the old value(depend on the …

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Windows NT 4 weird behaviour on track boundary read sectors?

Posted on 2020-01-29, 17:24

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by superfury

in PC Emulation

in PC Emulation

I notice some weird behaviour by Windows NT's setup booting when it starts to read the files from disk into memory(the log is of Windows NT setup being loaded)? CHS=>physicalmemoryaddress 9,1,3=>49e00 9,1,4=>4a000 9,1,5=>4a200 9,1,6=>4a400 9,1,7=>4a600 9,1,8=>4a800 9,1,9=>4aa00 9,1,a=>4ac00 9,1,b=> …

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Re: Any good MS-DOS 80386/80486/Pentium(on slow system) games for testing Protected mode emulation and instructions?

Posted on 2020-01-29, 00:45

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by superfury

in PC Emulation

in PC Emulation

OK. Trying to run "winnt /ox" from within UniPCemu for the correct "UniProcessor kernel" makes it complain about virtually every file after the first few, saying that the files copied don't match to the original? Edit: Looking at the files inside the disk image, it contains lots of 0xF6 bytes? Edit: …

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Re: Any good MS-DOS 80386/80486/Pentium(on slow system) games for testing Protected mode emulation and instructions?

Posted on 2020-01-29, 00:17

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by superfury

in PC Emulation

in PC Emulation

Hmmm... Windows NT 4 workstation says on the top of the crash screen "MultiProcessor Kernel"... Isn't that supposed to be "UniProcessor kernel" for the 80486?

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Re: Any good MS-DOS 80386/80486/Pentium(on slow system) games for testing Protected mode emulation and instructions?

Posted on 2020-01-28, 23:02

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by superfury

in PC Emulation

in PC Emulation

Hmmm... After recreating the disks using the latest virtualbox version, it still crashes virtualbox. But UniPCemu once again changes on NT 4: *** STOP: 0x0000006B (0xC000012F,0x00000003,0x00000000,0x00000000) PROCESS1_INITIALIZATION_FAILED Edit: And Bochs seems to be able to successfully boot using …

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Re: Problematic Windows games list

Posted on 2020-01-28, 20:49

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by superfury

in Windows

in Windows

Hmmm... If I remember correctly, the MS-DOS/Windows game Theme Park World of mine(EU edition?) has/had some issues with graphical glitching on Windows 10. It refused to start properly without a patch, and once it did it had some graphical issues still(e.g. slight screen tearing, seeing a (wavey) …

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Re: Any good MS-DOS 80386/80486/Pentium(on slow system) games for testing Protected mode emulation and instructions?

Posted on 2020-01-28, 19:45

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by superfury

in PC Emulation

in PC Emulation

Yay! Windows NT 3.1 is now booting and installing correctly! I managed to log in using the created user account! :D Edit: Hmmm... NTFS conversion didn't happen? Edit: OK. NT4 goes weird: It gives me a: STOP: c0000221 Unknown Hard Error \SystemRoot\System32\ntdll.dll So clearly no longer misdetecting …

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Re: Any good MS-DOS 80386/80486/Pentium(on slow system) games for testing Protected mode emulation and instructions?

Posted on 2020-01-28, 15:11

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by superfury

in PC Emulation

in PC Emulation

After fixing some 'bugs' with the FDC not keeping the Seek End flag intact in various cases(as well as invalid interrupts on implied seek, seek/recalibrate not clearing the ST0 bit while seeking(only setting it when completing), Read ID missing implied seek functionality(completing seek to the …

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Re: Preserving segment registers across task switch

Posted on 2020-01-27, 20:37

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by superfury

in PC Emulation

in PC Emulation

It seems upon task switch, one of the action the processor takes is this: "Saving the state of the current task. The processor finds the base address of the current TSS cached in the task register. It copies the registers into the current TSS (EAX, ECX, EDX, EBX, ESP, EBP, ESI, EDI, ES, CS, SS, DS, …

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Re: Any good MS-DOS 80386/80486/Pentium(on slow system) games for testing Protected mode emulation and instructions?

Posted on 2020-01-27, 01:43

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by superfury

in PC Emulation

in PC Emulation

Jazz Jackrabbit still seems to hang during it's intro? Still no more than a static blue screen(no sound) in protected/V86 mode(himem and/or emm386 loaded), crashes on real mode(stack fault)? And without sound settings it will display a graphic message to run setup.exe, returning to MS-DOS? Hmmm... …

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Re: Any good MS-DOS 80386/80486/Pentium(on slow system) games for testing Protected mode emulation and instructions?

Posted on 2020-01-23, 23:32

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by superfury

in PC Emulation

in PC Emulation

Just tried NT 4.0 workstation as well(since 3.1 seems to, well, boot(except no proper floppy support)), but it results in the old STOP: 0x0000007B(0xFF6378D0, 0, 0, 0) BSOD (INACCESSIBLE_BOOT_DEVICE). So there's still some unknown issue that's causing it to not be able to boot the second floppy disk …

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Re: Any good MS-DOS 80386/80486/Pentium(on slow system) games for testing Protected mode emulation and instructions?

Posted on 2020-01-23, 19:38

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by superfury

in PC Emulation

in PC Emulation

Hmmmm... It was expanding the bits from the set/reset register literally accross all 4 planes(e.g. 0x6 becomes 0x06060606 on the dword in VRAM). It's supposed to do something different instead(0x00FFFF00(setting plane 1&2 to 0xFF instead of all planes to 0x6)) as the input to the bitmask operation? …

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Re: Any good MS-DOS 80386/80486/Pentium(on slow system) games for testing Protected mode emulation and instructions?

Posted on 2020-01-23, 18:11

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by superfury

in PC Emulation

in PC Emulation

Hmmm... I see it writing to VRAM (when starting the GUI) values 0xFF with a map mask register of 0xF.\ The renderer is in plain planar mode, so it's a plain 640x480x16 graphics mode that's setup. Weirdly, all VRAM is(when the GUI is started) filled with 0x6 bytes, thus resulting in the pixels …

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