6502 Instruction Timing Tests

[blargg]

This iNES file tests 6502 instruction timing for all documented instructions except branches, both with and without a page crossing. It also tests some of the undocumented NOP instructions, but no others. If it finds a problem, it prints the opcode and the number of clocks it timed along with the correct timing. It's a bit complex so post if you encounter any odd problems. No source code yet.

cpu_timing_test.zip

[Quietust]

Just how long does this take to run? I get the text "6502 TIMING TEST (12 SECONDS)" for a split second followed by a solid black screen for about 12 seconds, then the screen flashes white and turns blue-violet (and then flashes white every so often).

[blargg]

I'm not sure what's happening on your end. I made a few changes to the text console initialization in the version below, but I'm not seeing what could be happening. What kind of hardware are you running it on?

cpu_timing_test2.nes

[mattmatteh]

first run i got fail op :$f8
then uncommented flag_d = 1;
then i got passed

i could search the forums if the search worked, how does the nes handle the d flag ?

both test (cpu_timing_test.nes and cpu_timing_test2.nes) ran the same except the second one removes '6502 timing test (12 seconds).

matt

[mattmatteh]

i just tested nestest and nestress again.

with my d flag code commented out i get:

nestest: fail code 13 flag test
nestress: cpu all ok

with my d flag code enabled i get:

nestest: all ok
nestress: cpu sbc error in d-flag

i am stumped

matt

[Quietust]

Evidently, that ROM does something screwy that my emulator doesn't like; exactly what is going on, I have no idea. Naturally, it works fine on my CopyNES's RAM cart.

If anybody's interested, a partial CPU log can be found at http://qmt.ath.cx/~nes/cputiming.zip

[mattmatteh]

i tried to unzip your file Quietust and it failed:
skipping: cpu_timing_test2-1.20060915_005436.debug need PK compat. v4.6 (can do v2.1)
how are you zipping that ?
matt

[blargg]

Here's the (somewhat unpolished) main source, in case it helps: cpu_timing_test.asm The main obscure thing I'm doing is filling the stack with the value $02 to allow thousands of repeated RTS and RTI in those tests, without having to keep refilling the stack. The test loop is copied to $200-$210 or so. RTS should return to $203, and RTI to $202 (the loops are adjusted accordingly). This will require proper stack wrap-around, for one.

mattmatteh, not sure why your emulator is failing. The SED instruction should add two clocks to execution time and set the D flag. The D flag has no effect other than it being remembered; the NES 6502 does not have a decimal mode. I can't imagine why not setting that flag would affect anything timing related. I've found Nestress to be useless as a test since it reports errors for some things when they are working correctly. I recommend Kevtris' NESTEST for a thorough CPU test.

[mattmatteh]

i just noticed that your first version gives failed op f8 unknown error, and the second gives unknown error f8.

i looked at your source and if i read that right, there are 4 locations that jump to error. is that the code where it would cause fail ? perhaps you could separate those errors ?

thanks

matt

[blargg]

mattmatteh, try this and post the 16-bit hex value it prints at the end of the unknown error report:

cpu_timing_test3.asm

[mattmatteh]

blargg, $0456

thanks
matt

(g'night)

[CaH4e3]

Fixed $E2 timing, test is passed now.

[blargg]

mattmatteh, looks like a CPU error that NESTEST isn't catching. The timing for $F8 is correct, but it's failing in the comparison routine that has a bunch of SBCs in it. Hmmm, could it be that you're supporting 6502's decimal mode?!? The NES does not have that mode; it ignores the D flag. That would explain why it worked when you disabled the flag_d = 1 code! Sounds like your problem. Argh, I guess NESTEST isn't bulletproof after all. :)

[Quietust]

i tried to unzip your file Quietust and it failed:
skipping: cpu_timing_test2-1.20060915_005436.debug need PK compat. v4.6 (can do v2.1)
how are you zipping that ?
matt

The file is BZIP2-compressed - 7-ZIP should be able to extract it properly, and I'd be surprised if WinRAR or WinZip were unable to do the same.

[Muchaserres]

I get "fail op :$04 UNKNOWN ERROR". May it be that I'm not implementing 2-byte NOPs? Which are those ops? Are those "official" (I mean, are those in the real thing)?

Thx.