chip8-test-rom VS chip8-test-suite

i ran the test rom https://github.com/corax89/chip8-test-rom/ and it said all opcodes are good except for 8XY1 - 8XY5.

So I've been on the fringes of understanding and writing an emulator for a while and decided to take the plunge with a CHIP8 emulator since it's well understood and a good starting point. I'm writing in C# and I've implemented most things to get it working however when I run This test ROM my output seems to stop at AX. I've tried debugging but I can't really see anything wrong with the code so I'm wondering if anyone has seen this issue before and might know what would cause this in general terms.

I was able to get the IBM Logo working(although the position of the logo is not consistent) but when I try to run this test rom, I get a flickering sprite and a bunch of 0x0000 Opcodes.

Hi, I am a total newbie in emulator development. I implemented a Chip8 emulator in JavaScript, finished it, with unit tests. However, when I load a test rom from https://github.com/corax89/chip8-test-rom the display looks jumbled instead of what supposed to be (in that README on that repo).

It may help to know that that first one isn't testing what it says it's testing: https://github.com/corax89/chip8-test-rom/pull/9

For anyone looking to write a CHIP-8 emulator, Matt Mikolay's writeup is less ambiguous:

https://github.com/mattmikolay/chip-8/wiki/CHIP%E2%80%908-Te...

If you want to target the original Cosmac VIP behavior, corax89's test ROM is good:

https://github.com/corax89/chip8-test-rom

I probably did them in numerical order, although it might be useful to pick a test ROM (second option) and implement instructions in the order they're used in that ROM.

I have been going through, implementing instruction by instruction and I've been having difficulty with instruction 00EE. When testing it with this test rom and I've been getting an output of this:

It's really hard to track down the issue with just this video. Have you tried the test ROM? https://github.com/corax89/chip8-test-rom

Also, this ROM is very useful to ensure you handle opcodes correctly

This is my first emulator. It is still missing a few bells and whistles like the sound timer, but otherwise it passes the basic tests from Timendus (https://github.com/Timendus/chip8-test-suite). I've also been thinking about making a Fortran dialect suitable for CHIP-8 (https://fortran-lang.discourse.group/t/fortran-chip-8-interp...).

Here is a reddit threadfor documentation resources and apparently the r/EmuDev discord has even more. Personally i used wikipedia and youtube to understand what it was & what it should look like (i remember still not getting it at first) and then Cowgod's Chip-8 Technical Reference as main reference for implementing the Instructions and overall architecture (beware that some instructions are missing key details about flag updating and other stuff another source will need to be used). Then the Chip8-test-suite by Tim Franssen was a godsend for the debugging phase. (you can go to Octo and try out some Chip8 games first if you want) also download some game-roms for testing.

Oh and with "test ROMs" I didn't mean "test with more ROMs", but use ROMs that are actually meant for testing 😉 See for example https://github.com/Timendus/chip8-test-suite

The emulator still has issues but it is largely usable. It passes most of the tests in test ROMs that I have found, in particular the ones here. It also has a simple debugger that actually helped me find issues in my implementation.

thanks alot man! i'll now run the roms in chip8-test-suite...

If you're at this point in the chip8 process, you may be able to run something like https://github.com/Timendus/chip8-test-suite to identify some common issues such as forgetting to set a flag or doing arithmetic operations slightly wrong. Maybe one of these common issues is the culprit.

I'd recommend trying this test ROM instead: https://github.com/Timendus/chip8-test-suite