28 Jun
2005
28 Jun
'05
7:02 p.m.
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"?
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29 Jun
29 Jun
4:47 a.m.
On Tue, 2005-06-28 at 22:02 -0400, der Mouse wrote:
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.
Certainly my Elan programmer likes to know what specific manufacturer
made the device it's programming, rather than just a general class of
device. As found out recently, it doesn't seem capable of handling
three-rail devices though, which is a shame. It's old enough that it
won't do anything about 1MBit either, although that's rarely a problem
for classic stuff.
It uses plug-in cartridges which define the devices that it knows about
(it's a PAL programmer as well as EPROM), uses a Z80 as the CPU, with a
keypad for user control and LCD for display - I/O to a host is via
serial, in a variety of user-selectable data formats.
Wish I had the specs for the cartridge data format so I could add other
stuff.
Building a similiar sort of thing based around an S100 CPU board (say)
could be in interesting project for someone; if the PAL side of it is
ignored then it's probably not *that* complex a task.
cheers
Jules
3:39 p.m.
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
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