Re: Maplin Z80 SBC
Ah, then the 2716s I offered to let you have probably wouldn't have solved your problem. Although in brand-new never used condition, they are Intel i2716 dated '77, so they almost certainly require 25V VPP.
My high-end device programmer from the mid '90s (£800+ at the time) does 25V devices OK, like you I am surprised that any device programmer made post-period did not allow for the possibility of 25V devices. Staying with 2716 EPROMs I think someone pointed out that there is one version in particular, possibly Texas/Ti, which has non-standard power requirements even in read mode.
The whole issue of VPP voltages varying from one brand to another is a bit of a minefield - moving on to slightly later/larger devices, you start to see some which only require 12.5V VPP rather than 21V VPP.
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