Dosbox has a debug version: DOSBox debugger Guide to the DOSBox debugger It's been a while since I used it, but I remember it provides the basic register / memory dump / breakpoint function.

Thanks so much, these look promising. Can't wait to try them out 😀

Hi, Are there any utilities (or source code) to thouroughly test all aspects of the VGA? I'm looking for something that tests all video modes 00h - 13h, and maybe some advanced features like split-screen and pixel panning... So far I've ported most of the samples from Michael Abrash's Black Book to …

Also, as a side note, the mode 13h is an oddball in fact: it sets the 8BPP mode(8-bit color enable in the Attribute Controller registers), 4-bit pixel from the sequencer(which IS rendering 640 4BPP pixels horizontally, just like any 640 4-bit EGA/VGA color mode. So the Sequencer and the CRTC are …

Hi, Working on VGA aspect of my PC emulator, but stuck on which register(s) determine 320 vs 640 pixels in horizontal. https://wiki.osdev.org/VGA_Hardware http://www.osdever.net/FreeVGA/vga/vga.htm These registers I understand: End Horizontal Display (3d4 index 01h) set to number of character clocks …

Hope someone here knows how to get this to work. This is my first time trying this emulator. I would like to get a 386 machine to boot a standard MSDOS 6.22 1.44Mb floppy image. Right now all I see, after the message flashed to press select for the settings, is a blank window with a tiny menu in the …

Thanks for the replies. For now I've used similar debugging methods - I look for an address that's hit only once, and single step from there, comparing the execution against Bochs. I think using Bochs instrumentation plugins to customise it's logging to match mine will make this easier. I also like …

Hi all, I'm working on a PC emulator project, to learn more about the workings of the hardware. My goal is to have accurate emulate of a Pentium system circa 1996. So far I have implemented: - majority of x86 instruction set (real mode) - 8259A PIC - 8253/54 PIT - 8237 DMA controller - 8042 keyboard …