Programming 2708's

[Tony Duell]

> 
> All this talk of 2708s and how to program them makes me wonder....
> 
> I've got some PROMs of various sorts (mostly UV-erase, but a few 28xxx
> EEPROMS).  I'd like to throw together a burner.  But to this end, I
> find I care about things such as differences between one maker's 27512
> and another's.
> 
> Is the sort of trouble described for the 2708 something that was worked
> out of PROMs early in their existence, and for later devices I can use
> pretty much any manufacturer's data sheet, or do I have to make sure I
> use a reference that corresponds to the exact maker and chip I'm trying
> to write?  If the former, what counts as "later"?

I think it got simpler later on :-)

For 2716s (single-rail, anything but TI) up to 27128s (at least) you can 
use the non-intellent algorithm of 1 50ms programming pulse per location. 
The only non-stnadard voltage is Vpp (which may be 25V, 21V, or 12.5V 
depending on the device), which is applied throughout the programming 
operation, it doesn't need to be pulsed. You can program the locations in 
any order, you can miss out locations, just program the ones you want, etc.

For 2764s (I think) up to 27512s you can use the intellegent algorithm. 
Here you give 1ms pulses per location (again, any order) and verify the 
written data (I think with Vcc raised to 6V or something like that). When 
the data verifies correctly, you give 4 times as many 1ms pulses to that 
location again. Most of the time (but don't assume this), the data is 
stored after a single 1ms pulse).

AFAIK the manufacturer doesn't make too much differnece here. My old 
programmer just has a device type setting, there are no 
manufacturer-specific settings. It does 2716 up to 27512 and some other 
odd devices, I think.

-tony