Re: Jazz Jackrabbit and SB 2.0 without config.sys?

Posted on 2020-02-06, 15:57

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by superfury

in PC Emulation

in PC Emulation

OK. This is a list of written bytes: 0xE1(Version command). Gives 2.1(firstbyte.secondbyte). 0xD1(Enable speaker). 0xE1(Version command). See first call. 0xD1(Enable speaker). 0x40(Set time constant). 0xAE(Set time constant parameter: 12195Hz) 0x1C(Auto-initialize DMA DAC). This uses a block size of …

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Re: Jazz Jackrabbit and SB 2.0 without config.sys?

Posted on 2020-02-06, 15:01

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by superfury

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Well, that very first DMA transaction is weird as well(at least on the SB side, haven't checked the DMA chip yet): the DMA block size(which was set immediately before that) is set to 0, thus only 1 byte(sample) of audio before issuing it's interrupt? Is that supposed to happen normally?

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Re: Welcome to the updated VOGONS

Posted on 2020-02-06, 12:28

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by superfury

in Milliways

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Is the "\ VOGONS" at the end of the page title really supposed to be there? It sounds a bit weird?

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Jazz Jackrabbit and SB 2.0 without config.sys?

Posted on 2020-02-05, 10:51

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by superfury

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I can see that, somehow, Jazz Jackrabbit crashes when configured for Sound Blaster and using a Sound Blaster 2.0 card on UniPCemu(DSP reporting as version "2.o1". DSP Version "2.00" (older UniPCemu builds) before that change don't crash it). https://bitbucket.org/superfury/unipcemu/src/master/ …

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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 2020-02-04, 22:12

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by superfury

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OK. The last release of UniPCemu(from 20190728) still ran Jazz Jackrabbit without visible issues. So now it's just a matter of applying newer commits until it fails to run properly? Edit: 20190731 is also confirmed to be running(that includes the install of the most recent commits). So the …

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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 2020-02-04, 19:55

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by superfury

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Just tried WinCheckIt 4 on Windows 95. It no longer crashes when collecting data about the hardware etc.(mainly the Bus type and FPU detection parts). That's probably due to the MOV to/from memory and AL/AX/EAX bugfix(and a certain modr/m mov instruction using said address incorrectly after said mov …

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

Posted on 2020-02-04, 13:38

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by superfury

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What happens when you try to read the last sector on a disk? Since it reaches EOT on this disk in MT mode, the head will flip and the sector number will reset. Also, the cylinder number would increase to out of bounds. As far as I know, with the BIOS booting up seeking the disks to detect 40/80- …

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

Posted on 2020-02-03, 21:21

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by superfury

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Just have been thinking about something: what exactly clears the disk changed flag? It's a function of the drive not the controller so different drives might be different. The common Teac fd-55gfr manual (https://deramp.com/downloads/floppy_drives/teac/TEAC%20FD-55GFR.pdf) says it's cleared when a …

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

Posted on 2020-02-03, 07:29

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by superfury

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Just have been thinking about something: what exactly clears the disk changed flag? All the documentation I find says when the FDC seeks the disk, but is that only when executing disk seek(0xF) commands? What about read(ID/sector)/write/format commands? And read/write with implicit seek? Hmmm... …

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

Posted on 2020-02-02, 04:18

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by superfury

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Hmmmm... What does actually happen when the FDC receives a Sense Interrupt command(0x08) with no reset pending or interrupt? Of course, it will give 0x80 as the error code(invalid command) but what after that's received by the OS? Will the controller lock up? Or is this standby state a different …

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

Posted on 2020-02-02, 01:35

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by superfury

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OK. Just found out that Windows NT 3.1 only can boot it's first disk when using a 80386. When using the 80486 or Pentium CPU emulation, it simply ends up with a black screen? Edit: OK. The same happens with a 80386. The CPU itself hasn't changed. The only thing that did change was the FDC itself. So …

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

Posted on 2020-02-02, 01:01

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by superfury

in PC Emulation

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Just modified the handling of the reading, writing, formatting and read ID commands to (with the exception of formatting) find the requested sector number on the track, then using said found sector on the track, instead of actually using the nth sector on the track. Reading/writing/Read ID now …

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

Posted on 2020-02-02, 00:09

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by superfury

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OK. So it's basically impossible on a plain XT/AT/Compaq Deskpro 386, except for being able to change the DMA controller by quickly writing the count registers to 0(although it will still transfer 1 byte, which will cause an incomplete command of 1/512 bytes being transferred of a sector, then …

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

Posted on 2020-02-01, 22:39

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by superfury

in PC Emulation

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OK. So the only way to actually send TC is by a DMA transfer to go from 1 left to 0 left, setting TC and thus making the floppy disk go to result phase? I suppose but I don't know of anyone whose tried it. It's possible that different 8237 implementations (chipsets etc) might not handle that …

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

Posted on 2020-02-01, 22:16

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by superfury

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Also, the floppy not knowing about EOT is obviously not the case: it can see the index hole being passed by, so it knows it's reached the end of the track?

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

Posted on 2020-02-01, 22:14

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by superfury

in PC Emulation

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But with PC XT or AT/Compaq/more modern architectures, the only one to drive TC is DMA afaik? which is why it doesn't work properly on pcs where tc is only connected to the dmac. OK. So the only way to actually send TC is by a DMA transfer to go from 1 left to 0 left, setting TC and thus making the …

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

Posted on 2020-02-01, 21:50

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by superfury

in PC Emulation

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But with PC XT or AT/Compaq/more modern architectures, the only one to drive TC is DMA afaik? How is it driven with modern motherboards? Can the CPU trigger TC without a DMA transfer being active? If so, how(currently emulating XT, AT and Compaq Deskpro 386)?

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

Posted on 2020-02-01, 20:33

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by superfury

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What about non-DMA(polling?) modes? Since non-DMA doesn't use DMA, TC should probably be ignored? Then would in non-DMA mode the EOT setting be the only way to make it end a command that's transferring sectors(so, by sector overflowing(when sector>EOT and not MT))? I've been wondering for a bit …

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

Posted on 2020-02-01, 14:54

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by superfury

in PC Emulation

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OK. With those latest improvements, Windows NT 3.1 workstation boots fine on a 80386, but on the 80486 it crashes with a message saying that windows wasn't copied/installed correctly and please run setup again?

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

Posted on 2020-02-01, 10:51

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by superfury

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Hmmmm... Just have been thinking... Currently, the FDC stops a read/write operation when the (previously mentioned) EOT is reached(either byte 6 of the parameters or the geometry's SPT setting during DMA MultiTrack(MT) mode). Previously, when it was successfully installing Windows NT 3.1, it stopped …

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