Today, for the second time, I tried programming a 16F84 in my self-built
programmer at work (normally I use a BP Microsystems unit, but on this
occasion my self-built one was hooked up).  Unfortunately, my programmer
doesn't seem to work on any non-blank 16F84's (it worked fine for reprog-
ramming 16C84's).  My suspicion is that Microchip has changed the opera-
tion of the "program word" instruction so that it no longer does an erase
before write.

[1] Is there any way to erase a word of code space on the 16F84 without
    erasing the whole thing?

[2] How should I erase the whole thing if needed?  I'm running in serial
    mode.  I tried the command someone posted once but it didn't seem to
    work; maybe I misremembered it?

[3] If the part no longer does an erase-before-write, does this mean that it
    can be programmed any faster?  Is there any way to see if the device is
    done with a spot (other than waiting 10ms)?

Thanks for any and all assistance.