Wanted: ASM-48 for Intellec MDS-2

Mike Stein mhs.stein at gmail.com
Wed May 20 00:28:27 CDT 2015

My 8041A/8641A/8741A data sheet says
"interchangeable ROM and EPROM Versions", "Single
5V Supply" and "Vdd (Power): 5V during normal

I'm pretty sure I've read 8741s without any 25V
supply; AFAIK Verify mode is not the same as Read 
('normal') mode.


----- 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.

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