Re: [stella] EPROMs

Subject: Re: [stella] EPROMs
From: Chris Wilkson <ecwilkso@xxxxxxx>
Date: Mon, 3 Sep 2001 21:18:43 -0400 (EDT)
On Mon, 3 Sep 2001, B. Watson wrote:

> Ah, excellent... now if only I could *erase* the 27c256's.. 1/2 hour under a
> UV lamp didn't do it. The UV lamp I'm using, though, was made for something
> else (growing plants indoors, maybe? or for keeping pet reptiles warm & happy?)
> so it's probably never going to work... I'll leave them in there until I can't
> stand to wait any more (4-5 hours probably) and hopefully they'll be erased, or
> at least not permanently damaged.

Go to and search for "eprom eraser".  The Datarase II is the
one you want.  It costs $40 (maybe $50 by now) but it'll erase chips in under
5 minutes.  And it's much safer than having unshielded UV kicking around.
Any UV light (plants, animals, etc.) won't be intense enough to do the job

> I've also found another 27256-like chip on an old SCSI controller, the part
> number is NM27256Q and the manufacturer's mark looks exactly like the world
> war II `SS' symbol, only mirrored and rotated 90 degrees.. like this:
>  /\/
>  /\/

This is National Semiconductor.

> ...I've got a bunch of manufacturers and part numbers listed in the manual,
> so if I knew who the manufacturer was, I could maybe find out the Vpp.. though
> the way this thing works, you just get a menu of part numbers and it never
> tells you what voltage goes with what part number. Either I've fried 4 2716's,
> or they were bad to begin with. The 27C256B's will read and program, so if I
> can get them to erase, I have 4 32K EPROMs I can program and put in carts (but
> I don't really have 4 carts I want to destroy)

That's the way most programmers work.  It make things a lot easier for the
user.  Mine allows you to adjust verious voltages after you select a part,
but I never do really.

You don't need carts...just a board that will accept the chip.  You can use a
screwdriver to open the dust slot on the console.  A toothpick is better if
you're paranoid.  Just stick it in either of the little slots on the cart
port and the center hole (where the PCB enters) should open up nicely.  :)


Archives (includes files) at
Unsub & more at

Current Thread