EPROM Emulator Proposal

[Terry/Carol Kelley]

Hi Tom,

I agree. Real picky.

To me, once the editing is done, the program on the PC with contain the
complete image. That can by used to burn a final eprom.

You need to keep in mind that we will be using a portable PC or a very long
extension cord. It is unlikely you will have an eprom burner with you in the
car.

Unless everyone is intending on having an active circuit running for a
"fake" prom, this is a better solution. Edit on the pc and burn a final
eprom.

So who is it that is going to design this emulator?

Terry Kelley

1986 Olds Ciera GT 3800 Supercharged

-----Original Message-----
From: thergen at svn.net <thergen at svn.net>
To: gmecm at esl.eng.ohio-state.edu <gmecm at esl.eng.ohio-state.edu>
Date: Wednesday, April 07, 1999 3:27 PM
Subject: Re: EPROM Emulator Proposal


>Battery backed rams I've used have usually been very picky about the
>states of chip selects during power-up/power-down/power-off.  It's very
>easy to do an accidental write to an arbitrary location.  Often, chip
>selects and write enables are active low.  Low is where all the signals go
>during power-down (hence the need for the special handling of chip
>select).  Chip select level(s) during power off may also determine whether
>or not the lowest power state is entered which can severly affect backup
>battery life.
>
>Tom
>
>On Wed, 7 Apr 1999, Squash wrote:
>
>> But if dpram is battery backed, there should be no
>> need for a weird circuit on power-up, right?  It would
>> act just like an eeprom?
>>
>> Andy
>>
>> --- thergen at svn.net wrote:
>> > I think it's a good proposal.  I'd like to suggest
>> > that a pushbutton
>> > switch be part of the design that can be used to
>> > reload the default dpram
>> > bank from the eprom (assuming it's present) so that
>> > you can recover from a
>> > corrupted ram image without using a laptop computer.
>> >  Power-up/power-down
>> > need special attention (as you already know) to
>> > avoid corrupting the ram.
>> > Maxim (www.maxim-ic.com) and others make parts with
>> > voltage supervisors
>> > specifically for memory protection (let me know if
>> > you want specifics).
>> >
>> > Tom
>> >
>> > On Wed, 7 Apr 1999, Ludis Langens wrote:
>> >
>> > > The EPROM emulator debate on this list seems to be
>> > going in circles.
>> > > Either people have short memories, or there are a
>> > lot of new members who
>> > > missed the discussion and decisions made in the
>> > first few weeks of
>> > > gmecm.  Either way, please read through the
>> > archives.
>> > >
>> > > Anyway, here is an emulator proposal based on the
>> > prior discussion.  I
>> > > did some ruthless cutting of features and
>> > expandability (indicated with
>> > > a *).  I propose the use of a single dual-port
>> > SRAM (from Cypress or
>> > > IDT) and a 40/44 pin PIC microcontroller to load
>> > this RAM.  A battery
>> > > back up will keep the SRAM alive.  This allows an
>> > ECM to boot from the
>> > > DPRAM immediately upon power-up.  The whole
>> > emulator circuit board
>> > > should be small enough to fit inside a
>> > '165/'727/'730/'749/'808 ECM.
>> > ....
>> >
>> >
>> >
>> >
>>
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>
>