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Terry Yager
February 21st, 2004, 09:14 PM
Ever look at an eprom? Ever wonder how come they have a little round window looking in onto a square chip? What genius thought that up, and why did everyone else follow his (bad) example?

--T

CP/M User
February 22nd, 2004, 12:17 AM
"Terry Yager" wrote:

> Ever look at an eprom? Ever wonder how
> come they have a little "round"
> window looking in onto a "square" chip?

No, I was told that it was put there so you
could easily erase the contents of the
EPROM.

I've done a little EPROM programming quite
some time back & for memory it was easy
to mess up the EPROM (well perhaps the
way I was programming it). So you needed
the Window to erase the contents if
anything did go wrong.

> What genius thought that up, and why did
> everyone else follow his (bad) example?

Check above, I believe I've answered it (I
hope!). Though I think it's quite easy to think
down this path. But anyway! :-)

Cheers,
CP/M User.

dongfeng
February 22nd, 2004, 03:04 AM
The one's I used at university, you had to shine a magical light into it to erase the contents - then you could program then in again :D

Usually they have a sticker over it, just in case you shine an untraviolet lamp inside your computer.

shirkahn
February 22nd, 2004, 04:01 AM
The one's I used at university, you had to shine a magical light into it to erase the contents - .

And to think all this time I've been using white-out!
I guess that's why I never quite got the hang of burning my own eproms
-Chis

Terry Yager
February 22nd, 2004, 09:52 AM
Yes, I know what the window is there for, my question is, why is it round? Wouldn't a square window be a more efficient use of space? (I mean, I was always taught not to try putting square pegs into round holes, etc).

--T

carlsson
February 22nd, 2004, 12:17 PM
Maybe it has something to do with light distribution once you shine the UV light onto the chip. The round hole will not have any corners where light may not reach etc. This is a purely novice guessing though.

CP/M User
February 22nd, 2004, 12:51 PM
"Terry Yager" wrote:

> Yes, I know "what" the window is there for, my
> question is, "why" is it round? Wouldn't a square
> window be a more efficient use of space?

AFAIK, it doesn't work like that. It needs to be
round in order for the light to completely clear the
memory. In order for it to be a square, it would
need to be bigger, hence a waste of space! :-)

> (I mean, I was always taught not to try putting
> square pegs into round holes, etc).

Oh well, one day when you're building your own
EPROMs, you can make the window square, &
test it to see what happens! :-)

Cheers,
CP/M User.

Terry Yager
February 22nd, 2004, 02:08 PM
Oh well, one day when you're building your own
EPROMs, you can make the window square, &
test it to see what happens! :-)

Cheers,
CP/M User.

Ok, yeah. I'll try that (whenevr I get 'round to working with the actual silicon).

--T

CP/M User
February 22nd, 2004, 02:44 PM
"Terry Yager" wrote:

> Ok, yeah. I'll try that (whenevr I get 'round
> to working with the actual silicon).

That's the spirit! :-)

Cheers,
CP/M User.

dongfeng
February 23rd, 2004, 12:44 AM
when you drill a hole for woodwork, you use a drill that drills round holes not square ones.

I guess it's for the same reason?

Or you could be really fancy and have a hexagon.. or something.. :lol:

carlsson
February 23rd, 2004, 01:37 AM
I have a secret obsession for hexagons! More than one board-game based upon hexagons have been in my planning but never been realized. Not sure it fulfills any requirements on drilled holes or EPROM windows though.

CP/M User
February 23rd, 2004, 02:09 AM
"carlsson" wrote:

> I have a secret obsession for hexagons!
> More than one board-game based upon
> hexagons have been in my planning but
> never been realized. Not sure it fulfills
> any requirements on drilled holes or
> EPROM windows though.

I'd like to see anyone drill a hexagon into
an EPROM. It can't be done, as you'd end
up with a circle if you drilled too long! :-)

Cheers,
CP/M User.