If you're thinking of buying the 6502 Programming Manual, which is the definitive book on machine language, remember that the identical book is published by Commodore, by Synertek, and by Rockwell. Shop around: Commodore's price is higher than the other two.
The book is a reference, not a teaching book, and it has muddy spots, but it's complete and accurate. Anyone trying to tackle machine language should have one.
To find out if you have anything on cassette tape: mount the tape on cassette player #1, press PLAY and then hold down the less-than (<) key. You'll see instantly if the tape is empty or not. Works on both old and new PETS.
Received a hot flash from the Vancouver group, but it may require a little more work…
You can speed up the PET dramatically just by typing POKE 59458, 62.
Problems to be investigated:
Doesn't seem to work on units with the old 011 ROM. Why?
On other machines, there might be a danger of crashing very occasionally — it hasn't happened to me, but it seems possible when I study the system. If so, the fix is very easy; use:POKE 59458, 62 : POKE 59456, 223
which is 100% safe. Question: is this too cautious? Will the single POKE work every time? Experiment! Supply feedback!