19 May
2015
19 May
'15
10:28 p.m.
My 8041A/8641A/8741A data sheet says
"interchangeable ROM and EPROM Versions", "Single
5V Supply" and "Vdd (Power): 5V during normal
operation".
I'm pretty sure I've read 8741s without any 25V
supply; AFAIK Verify mode is not the same as Read
('normal') mode.
m
----- Original Message -----
From: "Eric Smith" <spacewar at gmail.com>
To: "General Discussion: On-Topic Posts"
<cctech at classiccmp.org>
Sent: Tuesday, May 19, 2015 11:09 PM
Subject: Re: Wanted: ASM-48 for Intellec MDS-2
On Tue, May 19, 2015 at 6:20 PM, Richard B.
Main, Esq.
<mainpatents at gmail.com> wrote:
That just sounds wrong to me applying +25v to
do a read/verify. You're
misinterpreting the datasheets. Richard
It may "sound wrong", but that's actually the
*only* way to read the
EPROM 8741, 8741A, 8748, and 8749. If you don't
apply high voltage to
the EA pin, it doesn't go into verify mode.
It's fully documented in
the data sheet, and I've verified that
commercial programmers do that.
It's possible that verification will work at
somewhat less than 25V,
but it definitely does NOT work at under 6V.
The issue is that the 8041, 8041A, 8048, and
8049 masked-ROM parts are
not rated for 25V on EA. The 8748 and 8749
datasheets say to use 12V
on EA. The 8041 and 8041A datasheets don't say,
but since it's almost
the same design and definitely the same fab
process as the 8048, I'm
pretty sure that they need 12V also.