Re: Can anybody help me debugging the MS-DOS 3.3 boot sector?
Posted on 2015-03-01, 14:21
Is that a bug in the MS-Dos 3.3 boot sector or is my emulator interpreting it the wrong way?
Can anybody help me get MS-DOS 3.3 booting in my emulator?
Posted on 2015-03-01, 13:43
I can't figure out what goes wrong here. All interrupts are set when my emulator starts, to point to my BIOS ROM (located at F600:0000+), which contains special instructions to defer to my internal emulator functions (using opcode FE /7). Most just contain an IRET instruction. Disassembly produced …
Re: Can anybody help me debugging the MS-DOS 3.3 boot sector?
Posted on 2015-03-01, 13:24
@Qbix: Not with Dosbox itself no (my own emulator in this case). Should I put this in a different forum? Edit: 'moved' (copied, since I can't delete this one) the thread to the PC Emulation forum.
Can anybody help me debugging the MS-DOS 3.3 boot sector?
Posted on 2015-03-01, 13:00
I can't figure out what goes wrong here. All interrupts are set when my emulator starts, to point to my BIOS ROM (located at F600:0000+), which contains special instructions to defer to my internal emulator functions (using opcode FE /7). Most just contain an IRET instruction. Disassembly produced …
BIOS interrupt 13h first read call with MS-DOS 3.3?
Posted on 2015-02-28, 18:19
I'm getting the following results for this first read to the floppy: CS: 0 IP: 7D74 DS: 0 ES: 0 SS: 0 AX: 0201 BX: 0 CX: 8E3C DX: 0 SP: 7bF2 BP: 0 SI: 102B DI: 7C36 Flags: 0206 OPCode: INT 13h Anyone can tell me if this is correct and how to decode this information to the floppy CHS format? (AX=0201 …
MIDI file playback using the MPU-401?
Posted on 2015-02-28, 11:33
I'm currently testing my MPU emulation (which is the Dosbox mpu.cpp as the 'front-end' and my own MIDI emulation (everything producing sound and processing the MIDI commands send to the output) as the 'backend'. I'm currently trying to get my .mid file playback correctly. I do get sound, but it …
Re: Can you nest a running windows session within an emulator?
Posted on 2015-02-28, 11:21
And, if you would boot windows (95) with virtual memory disabled both in the host and guest systems?
Can you nest a running windows session within an emulator?
Posted on 2015-02-28, 10:26
I'm just wondering. If you have windows 7 running from a partition on the hard disk, can you run the same windows partition within an emulator within windows? So: 1. My hard disk has a partition containing windows 7 or another windows version (usually the first partition). 2. I boot windows by …
Switching to video mode 4/5 leaves high planes untouched when clearing VRAM?
Posted on 2015-02-27, 11:09
I've noticed (when using the int10_modes.cpp code) in my own emulation of the VGA, that for some reason the switch to modes 4/5 leaves the high display planes (planes 2/3) untouched. When switching from text mode, which uses plane 2 for character fonts, or a graphics mode using 4 planes (16 color …
Re: 8237A DMA Controller emulation verification
Posted on 2015-02-26, 22:00
I'd rather keep it private, sorry. Still developing though.
Re: VGA emulation troubles with modes 4/5/6/F.
Posted on 2015-02-26, 16:18
So I need to adjust the int10_modes VGA settings of the source code to make it work on a real IBM VGA (which I'm emulating as far as I can find the documentation on it)? Or are the int10_modes settings correct and I need to fix my VGA script (which seems to have bugs)?
VGA emulation troubles with modes 4/5/6/F.
Posted on 2015-02-26, 13:46
I'm currently testing my VGA emulation routines using different graphics modes. Atm modes 0xF gives no output and mode 4, 5 and 6 give a quarter of the horizontal scanlines with (as far as I can see in the tiny window which contains the pixels) 8 or 9 pixels (depending on the 8/9 pixel character …
VGA Dot clock rate vs character clock?
Posted on 2015-02-25, 16:43
What's the difference between the VGA's Dot Clock rate (divide by 1, 2 or 4) and character clock (divide by 1, 2 or 4)? How does the DIVIDE SCANLINE CLOCK BY 2 affect ouput? How do any of them affect output?
Re: VGA Miscellaneous output register set incorrectly?
Posted on 2015-02-22, 15:02
My current code for read and write operations is: (OPTINLINE is a define which gives __inline or inline depending on the compiler) //decodeCPUaddress(Write from CPU=1; Read from CPU=0, offset (from VRAM start address), planes to read/write (4-bit mask), offset to read/write within the plane(s)). …
Re: VGA Miscellaneous output register set incorrectly?
Posted on 2015-02-21, 22:44
I've looked at the FreeVGA docs again: Sequencer Memory Mode Register bit 5 seems to have the highest priority, forwarding to all planes if set (using the read map during read or the bit mask during write to select the correct plane(s), sequentually accessing it). When it's set to 0, even addresses …
VGA Miscellaneous output register set incorrectly?
Posted on 2015-02-21, 16:34
When I look at the miscellanious output register, which is set at int10_modes.cpp, it sets bit 5 on always. Shouldn't this bit be cleared always? (When a real VGA gets the bit set, it will redirect all VRAM output to the high planes (plane 2&3 instead of 0&1), which will cause text modes to redirect …
How compatible are Dosbox's VGA registry outputs with the IBM VGA?
Posted on 2015-02-12, 21:01
I'm running my emulator with a copy of the int 10h service of dosbox, although some types converted to my emulator's types. I've based my VGA emulation on the FreeVGA specs and IBM documentation. I'm trying to get all video modes working (00-13h), but atm only mode 2/3 and the 16/256/mode 0xF color …
Re: 8237A DMA Controller emulation verification
Posted on 2014-03-25, 16:33
what isn't? the code should be visible? or the goto?
Re: 8237A DMA Controller emulation verification
Posted on 2014-03-24, 20:13
My compiler seems to have problems with some c++ code (it wont recognise anything if i try it. Using pspsdk, with uses gcc iirc). Gotos seem to be a little bit faster than an infinite for(;;) loop. I dont know if it works since I dont have anything to test it with (testsuite etc), nor have I written …
Re: 8237A DMA Controller emulation verification
Posted on 2014-03-17, 19:33
Update: /* DMA Controller (8237A) */ #include "headers/types.h" //Basic types! #include "headers/hardware/ports.h" //Port support! #include "headers/mmu/mmu.h" //Memory support! typedef void (*DMAWriteBHandler)(byte data); //Write handler to DMA hardware! typedef byte (*DMAReadBHandler)(); //Read …
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