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What is the diff between a 25x eprom and a 27x eprom.

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Anonymous
April 23, 2005 10:37:34 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

Title says it all, anyone have an answer. and can you program them just
like a 27x... 12.5v or what.

Thanks

John
Anonymous
April 24, 2005 1:10:57 AM

Archived from groups: rec.games.video.arcade.collecting (More info?)

The 25xx series is almost exclusively Texas Instrument TMS Eproms.

As the story goes, TI developed the TMS-2716 (2K Eprom),
but like the 2708 before it, it needed three voltages sources
to program/use them . This was more complicated and therefore more
expensive.

At roughly the same time, Intel also launched "their" 2716 chip
which was different than the TMS-2716 in that it only needed
a single voltage to program (25v) and a 5V to operate.
The Intel pinout was also a bit different than the TMS pinout.

Akin to the Beta Vs. VHS battle, only one could survive
and Intel proved to be the more popular, and thus, most
other manufacturers produced Intel-like 2716.

Bowing to pressure, TI also produced an Intel-like chip
but could not call it 2716 since they already had a 2716.
So they identified it as the TMS-2516.
And thus was born the 25xx series.

Recap :
TMS-2516 = Intel (and all other) 2716
TMS-2716 != other 2716
TI specific, limited use (..in arcade games anyways..)

Unfortunately, the story doesn't end there...

After the 2K chips came the 4K chips (xx32)

Intel simply used the same pinout as it's 2716
and added an extra addressing pin, thus the 2732.

TI again decided to use a different pinout
and to differentiate itself from the Intel 2732,
it named it the TMS-2532.

So 2532 != 2732

Virtually all 2532 you'll find are TI chips.
Only very few manufacturers other than TI made 2532.
(...I've only ever seen Motorola )

Most everyone again followed Intel's lead to create the 2732.

As far as I know, there is no TI 2732.
(...but TI stopped the madness by adopting the Intel
standard for all chips starting with the TI 2764 )

Also, unlike the TMS-2716, the TMS-2532 WAS pretty popular
and used in several applications (...notably arcade games. )

So it becomes a little tricky to know which 4K chips to use
in which game. PacMan for instance, uses 2532's, Williams
game Roms (Joust, Robotron, etc..) use "mostly" 2732,
but the boards can be jumpered to accept 2532.

So to answer your question, NO, 2732 and 2532 are NOT programmed
the same way and are not interchangeable without some board modifications.
Virtually ALL eprom burners will do 2732,
but some of the cheaper ones will not do 2532.

As for programming voltages, all early Eproms need 25V.
Chips ending with an "A" (like 2732A or TMS-2532A )
need 21V. The 12.5V is only used in "newer" Eproms (circa late 80's),
typically CMOS chips, like 27c010, etc...
(a good eprom burner with decent software will know which
parameters to use for each chip )

So as you can see, there are a number of factors to consider.

Hope this helps.

Cheers,
Steph
www.HobbyRoms.com



==================


jnhutch wrote:
> Title says it all, anyone have an answer. and can you program them just
> like a 27x... 12.5v or what.
>
> Thanks
>
> John
>
>
>
Anonymous
April 24, 2005 4:54:16 AM

Archived from groups: rec.games.video.arcade.collecting (More info?)

jnhutch <jnhutch@ev1.net> wrote:
: Title says it all, anyone have an answer. and can you program them just
: like a 27x... 12.5v or what.

2516 = 2716

The rest are different.

And you paid way too much for that dead 6100.

--
Mark Spaeth mspaeth@mtl.mit.edu
50 Vassar St., #38.265 mspaeth@mit.edu
Cambridge, MA 02139
(617) 452-2354 http://rgvac.978.org/~mspaeth
Related resources
Anonymous
April 24, 2005 5:45:53 AM

Archived from groups: rec.games.video.arcade.collecting (More info?)

HobbyRoms.Com <info@removespamhobbyroms.com> wrote:
: The 25xx series is almost exclusively Texas Instrument TMS Eproms.

What? No mention of the 2564, as seen on Zaxxon?! :) 

--
Mark Spaeth mspaeth@mtl.mit.edu
50 Vassar St., #38.265 mspaeth@mit.edu
Cambridge, MA 02139
(617) 452-2354 http://rgvac.978.org/~mspaeth
Anonymous
April 24, 2005 5:45:54 AM

Archived from groups: rec.games.video.arcade.collecting (More info?)

You see so few of these Eproms around that I didn't think it was
worth mentioning ! ;-)

Cheers,
Steph

Mark C. Spaeth wrote:
> HobbyRoms.Com <info@removespamhobbyroms.com> wrote:
> : The 25xx series is almost exclusively Texas Instrument TMS Eproms.
>
> What? No mention of the 2564, as seen on Zaxxon?! :) 
>
!