jose,

Back in my pre-flash days i had a prom eraser that very large to allow many 'proms to be placed inside. I eliminated the bottom tray which resulted in the Lamp sitting right over (almost upon) the prom's to be erased. I could erase an 8751 in ~ 5 min.

Although i was suspicious, always waiting for negative impact (soft bits or failed programming), in years of using the technique, i never did find a problem. I never did ship a prom erased this way but this was most likely because i used OTP for production.

regards,
p