On Fri, 24 May 1996, Andy David wrote:

> thanks for straightening that out, I've found the relevent paragraph
> now... so even OTP devices can have their unprotected ROM
> reprogrammed? I assume it's just the one extra time.

It's not a general reprogramming: you can only change 1 bits into 0
bits.  This is the same as you start out with for the whole OTP chip.
Until the other CP bit is set (and since they get set by being programmed
to 0 they can be set in two steps) you can program areas left in the
erased state.  If you're crafty you can change already programmed code,
but only by changing 1s to 0s.  This could still be very useful if those
1s and 0s are in the data part of a literal instruction...  :-)

(yeah, I thought about doing something like this - the idea was that I
could put two different builds on one EPROM part before I had to stop and
erase it, since the code (so far!) fits well within either of the 2K
banks.  But the practical difficulties of making sure the code assembled
for the correct placement and arranging to have the flag bit get
reprogrammed, etc, made this too much trouble for so little benefit.)