In article ,
John Robertson wrote:

it a 8K file of "FF"s so you aren't trying to burn 00s - this will speed
up the programming slightly.

It would *only* speed up programming if the hardware/software used
optimizes things and skips/refuses to "program" locations that
are 0xFF (the default blank chip state).

Otherwise, there's no speedup there.

I wasn't really worried about the speed,

Well, some programmers do optimise by "not-programming" 0xFF, which may
not make much odds on a decent programmer. I added this step to the
custom software for my EPROM programmer which talks over a 4800 baud
RS232 serial link, where every byte matters!

Same for a "Rapid blank check" (check 1024 bytes spaced through the chip
to check if they come up blank) for quick-sorting of blank vs programmed.

plus any unused space
(FFs) in the EPROM could still be used if the OP needed something else
in the future.

Yes, that's actually a good point -- I've used 27512 parts where I
really needed only a 27128 (with two spare high address lines tied to
jumpers to ground/pullup resistors) to allow four goes at programming
the chip before having to chip-swap or erase!

Or just erase and start over...which we've all done I'm sure!

Too many times
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Mike Brown: mjb[-at-]signal11.org.uk | http://www.signal11.org.uk