Some time ago, I benchmarked some 8-bit computers to find out the fastest BASIC interpreter. I ended up using the classic SAXPY benchmark, as I didn't want any I/O overhead to fool the measurement: printing on screen is slower for machines that doesn't have a real text mode and always operate in bitmap mode and it doesn't have to do with the BASIC interpreter itself. On the other hand, aritmetic routines play an important part in any BASIC program, so the benchmark does precisely that.
I'd like to add some other machines to this list, so I need to know how to measure time in frames (or equivalent resolution). For other computers, as you can see, the TIME or TIMER function is usually present in most BASIC dialects. For the Spectrum and the SAM Coupé, I already knew about the FRAMES system variable to count frames, but for others, I have to dig into technical documentation, which is not always available or easy to find/read.
Here is the current listing. NOTE: ("Tiempo en segundos" is the spanish for "Time in seconds").
The title says "Results of SAXPY benchmark applied to 80's classic computers".
UPDATE: thanks to Stephen Kitt answer, I can finally place the Atari XL, and it happens to be between the SAM Coupé and the ZX Spectrum.
As Stephen suggests, I will ask separate questions for finding out how to measure time for other micros.