which version?
at address **broken link removed** (bottom
page I give data to read a 68705P3;
I can also read 68705R3.
some 68HC705 can be read (not secured)
MB.
Nearly all HC705 can be read back - but not in the direct sense....
you need to single step through in VERIFY mode, trying each hex value from 00 to FF in each location, one at a time, until you can get through an entire pass without a fail...........
easiest to do with a little VB app controlling the MCU address lines via a PC parallel port............