Floppy Disk Controller result phase MSR value?

Posted on 2015-07-24, 19:35

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by superfury

in PC Emulation

in PC Emulation

I currently set RQM(bit 7)=1, Have data for CPU(bit 6)=1 and Busy (bit 5)=0 during the result phase. The controller remains in the result phase while there's result data to be read. Is this correct? So while reading the result bytes (e.g. during the 7 result bytes of a read floppy sector) bits 7 and …

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Re: Can anybody help me get MS-DOS 3.3 booting in my emulator?

Posted on 2015-07-23, 10:39

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by superfury

in PC Emulation

in PC Emulation

So eventually it calls an address called "MSDOS", according to the MS-DOS 3.30a source code (SYSINIT1.ASM). First, it executes a JMP to 0:02:29:15.3.0854: Read from memory: 0009E7C8=00 ( ) 0:02:29:15.3.0860: Read from memory: 0009E7C9=00 ( ) 0:02:29:15.3.0871: Writing to memory: 0009E938=FD (ý) 0:02 …

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Re: Can anybody help me get MS-DOS 3.3 booting in my emulator?

Posted on 2015-07-20, 17:31

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by superfury

in PC Emulation

in PC Emulation

I do notice that the memory is correctly detected by INT12: 0:01:53:92.2.0839: Read from memory: 000006F6=14 () 0:01:53:92.2.0845: Read from memory: 000006F7=36 (6) 0:01:53:92.2.0851: Read from memory: 000006F8=70 (p) 0:01:53:92.2.0856: Read from memory: 000006F9=00 ( ) 0:01:53:92.2.0861: Read from …

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Re: Can anybody help me debugging the MS-DOS 3.3 boot process?

Posted on 2015-07-20, 17:20

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by superfury

in PC Emulation

in PC Emulation

I'll have to investigate later what you're seeing. However, if you see reads to segment 0x70 while running from segment 0x70, then that's your problem. These are the reads that you should see: 9ea0:0 (9 sectors) 690:0 (6) 690:c00 (0x12) 690:3000 (0x12) 690:5400 (0x11) 986:10 (1) b72:10 (1) b72:10 …

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Re: Can anybody help me get MS-DOS 3.3 booting in my emulator?

Posted on 2015-07-20, 15:30

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by superfury

in PC Emulation

in PC Emulation

I've gotten MS-DOS running up to a certain point: 0:04:39:53.0.0508: Read from memory: 0009E7C8=00 ( ) 0:04:39:53.0.0515: Read from memory: 0009E7C9=00 ( ) 0:04:39:53.0.0525: Writing to memory: 0009E938=FD (ý) 0:04:39:53.0.0530: Writing to memory: 0009E939=9D () 0:04:39:53.0.0536: Writing to memory …

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Re: Can anybody help me get MS-DOS 3.3 booting in my emulator?

Posted on 2015-07-20, 10:33

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by superfury

in PC Emulation

in PC Emulation

Afaik I now have my DMA and floppy controller fully working. After the BIOS starts booting, first sector 0 of floppy #0 is read to 0000:7C00. When MS-DOS tries to load the FAT, it reads sector 19 to address 0x500 (debugging the DMA controller addresses)? After that, it says the disk is not a system …

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Re: Can anybody help me get MS-DOS 3.3 booting in my emulator?

Posted on 2015-07-20, 08:28

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by superfury

in PC Emulation

in PC Emulation

I now got the Turbo PC XT BIOS running up to the point it starts booting the floppy, but the DMA controller seems to go wrong: it doesn't seem to detect correctly when to start or stop. Anyone knows how the DMA controller operates (the differences between the 4 modes (Demand, SIngle, Block, Cascade( …

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ISA DMA emulation: how to handle TC and DREQ?

Posted on 2015-07-19, 20:49

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by superfury

in PC Emulation

in PC Emulation

At the moment, my emulator keeps checking the DREQ line (raised/lowered by the FDC). My FDC also raises the EOP line when it enters the result or error phase. How should the Terminal Count and different modes of operation be handled? Does the Terminal Count have any effect on transfers? What's the …

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Re: Can anybody help me get MS-DOS 3.3 booting in my emulator?

Posted on 2015-07-17, 17:10

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by superfury

in PC Emulation

in PC Emulation

My latest log of my emulator. It seems to loop? Anyone can tell me more about what's going wrong? I can't find it... Remove the ".zip" extension to use the archive and extract the log. debuggerlog_20150717_1902.7z.001.zip debuggerlog_20150717_1902.7z.002.zip debuggerlog_20150717_1902.7z.003.zip …

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Re: Emulator correct response to VGA predecessor I/O addresses and misc PC addresses?

Posted on 2015-07-14, 13:44

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by superfury

in PC Emulation

in PC Emulation

Should I include it as an option to be enabled (disabled by default) in my emulator? So the user of my emulator can enable the VGA NMI on precursor register access, which don't exist in my VGA? This will be in the advanced menu of course, since normal users won't know when to use it, together with …

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Re: Emulator correct response to VGA predecessor I/O addresses and misc PC addresses?

Posted on 2015-07-12, 22:37

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by superfury

in PC Emulation

in PC Emulation

Does the IBM VGA BIOS use this? Afaik compatibility is at the BIOS level, so the IBM VGA BIOS uses the NMI? Can anyone verify that?

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Re: Can anybody help me get MS-DOS 3.3 booting in my emulator?

Posted on 2015-07-12, 15:01

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by superfury

in PC Emulation

in PC Emulation

Is there anyone that can answer my question(s) active on this forum? Do you have time peterferrie? Or maybe anyone from the Dosbox/Bochs/QEMU team can help? Edit: The error is supposed to happen before 0:04:57:44.0.0206 and after 0:03:25:05.4.0105 after looking at it. Anyone can find an error there …

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Re: Emulator correct response to VGA predecessor I/O addresses and misc PC addresses?

Posted on 2015-07-12, 14:58

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by superfury

in PC Emulation

in PC Emulation

So my VGA should generate a Bus error NMI when any MDA/CGA/EGA-specific I/O ports,which don't exist on a VGA, are read/written from/to?

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Re: Can anybody help me get MS-DOS 3.3 booting in my emulator?

Posted on 2015-07-11, 11:38

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by superfury

in PC Emulation

in PC Emulation

My current log says this: 0:00:31:76.0.0565: Read 17/17 sectors from drive 00, start 126. Requested: Head: 1, Track: 3, Sector: 1. Start sector: 126, Destination: ES:BX=0690:00005400 0:00:31:84.3.0692: Function 02 called. 0:00:31:84.4.0957: Read 1/1 sectors from drive 00, start 1. Requested: Head: …

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Re: Emulator correct response to VGA predecessor I/O addresses and misc PC addresses?

Posted on 2015-07-10, 16:47

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by superfury

in PC Emulation

in PC Emulation

My current emulation writes the outgoing I/O (ASM OUT instruction or emulator handler doing the same, e.g. INT 10h handler) to all hardware devices. The hardware itself (VGA, PIC, PIT, DMA, Adlib, Debugger(See Bochs E9 Hack, but with some extras added for control of the emulator using a special …

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Re: Emulator correct response to VGA predecessor I/O addresses and misc PC addresses?

Posted on 2015-07-10, 15:09

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by superfury

in PC Emulation

in PC Emulation

What happens when multiple devices are listening to the same I/O port? Like port 0x61 (partly the Bus hardware (various bits with invalid parity and check enable, bits 2-7) and partly the PIT&PC Speaker(bits 0-1)). Are the bits supported filled and the rest always 0 or are the bits given filled and …

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Re: Emulator correct response to VGA predecessor I/O addresses and misc PC addresses?

Posted on 2015-07-10, 14:31

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by superfury

in PC Emulation

in PC Emulation

So the NMI is because the CPU can't find any hardware to address when that port is read from/written to without a CGA card installed?

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Re: Emulator correct response to VGA predecessor I/O addresses and misc PC addresses?

Posted on 2015-07-09, 16:08

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by superfury

in PC Emulation

in PC Emulation

I do know that some SVGA cards generate a NMI when the CGA ports are read/written from/to (CGA mode control etc.). Does the VGA have such an option or generate an NMI in those cases when only a VGA card is installed?

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Re: Bochs XOR instruction error with Zero and Parity flags?

Posted on 2015-07-04, 17:21

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by superfury

in PC Emulation

in PC Emulation

Is there a simple way to fix this? I need a normal dump for comparing it to my emulator (one dump per STOSW instruction executed).

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MIDI Channel 9(0-based) bank select 0x7F?

Posted on 2015-07-03, 12:13

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by superfury

in PC Emulation

in PC Emulation

I notice that in my emulator, when playing a MIDI file (.MID file) a bank select MSB/LSB pair is sent to my MIDI Synth with a bank number of 0x7F(127). Should the channel respond to this message? Since it's a piano and not a MIDI drumkit on this bank it shouldn't use this bank?

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