I figured operator error on my part. I have Altirra 1.7 with PAL Artifacting activated at boot. At least these games do work, so I should be able to figure out the kinks in my set-up.
Thanks much.
By the way, is there a better place to post Atari 8-bit emulator questions? the Emulator-specific forum seems to have more posts not pertaining to 8-bit machines. 8-bit emulator is currently my only way to go. The family 800XL has been shelved a few years ago with keyboard issues and a failing (1050??) disk drive.