I was thinking of having a PCB made up that would be very simple, just a 28-pin DIP layout on one side and a 30-pin socket or header row on the other. This would allow very easy connection of a ZIF to a ribbon cable for ECM use. With a little shaving, it could be used for direct ZIF/ECM placement on the header in the ECM.

Anyways, there's a minimum order to get the PCB made up of like 60 bucks I think. This could provide '18' pieces. That'd be like 3 bucks apiece or so. If anyone's interested in going in, that'd be cool. Just let me know, I'm not in any real hurry.

This is done by us pretty regularly by hacking into headers & splicing in legs on sockets, this would just be a cleaner way.

Good thought? If interest is there, I'll provide detail and alternates.
-Craig

Are you proposing an on-car adapter, like the ones Traxxion was getting input on a whiles back??? Something that would allow the file-safe from the OEM MemCal, and still permit an aftermarket PROM to override the OEM PROM???

Or just an adapter to permit burning the OEM MemCal in the Pocket Programmer without using the hacked header???

What I've been looking for is one of those aftermarket adapters that allow an unmodified MemCal to be used in conjunction with your 27C128 or 29C256 PROM, without any cutting or soldering. Like the JET adapter...

What I had in mind would require cutting the memcal and EPROM piece in half. The piece I propose, when combined with a ZIF and IDE socket PCB-level components, would replace the EPROM-half of the memcal-eprom stick.

I'm open to other ideas though...

Yeah, I'd like to see something like the JET adapter.

I tried something like this and failed at home. A professionally styled one I'd be very interested in...

Anyone want to post pics or drawings of what the ideal little custom PCB you'd find useful? Maybe we can get a couple things thrown onto the silkscreen.

Check Expresspcb.com, they hve layout software and such, that's where I am thinking of getting it done... Mabe some 2-transistor interfaces?

I'm interested...I've already modified a MemCal with a ZIF socket/29C256; it's running now...

But I'm open to alternatives...

I think we discussed this earlier on this board and some of the issues that I brought up had to do with shielding and the effects of crosstalk on any length of ribbon cable between the PROM and the ECM. But I remember someone saying that they had a setup like that in their car and it worked fine.

Sooo..... In lieu of that evidence, I guess I wouldn't mind setting up something where you could run a ribbon cable to a place in the center console (or some other handy place) where swapping out the PROM would be much easier than removing and replacing the entire ECM every time you want to change something in the PROM (or driving around with the ECM hanging below the dash for days on end ).

I am not really clear on if this is what you are talking about though, Craig. Am I understanding you correctly?

If so, I think this could make life a lot easier for us!

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

I had an idea... why not make something that connected all 66 pins via ribbon cable to the adapter, and you plugged your original memcal into the adapter along with a socket for your burning chips?

A pair of 34-pin floppy drive cables could be of benefit here - just grid a little off the sides on the ends that go into the ECM.

No killing of a memcal, either.

Ideas? Someone willing to proto a couple of these boards? I'd buy one that I could attach to the upper kick panel with an access hole for chip swapping.

Let me preface by saying that taking a hack-saw to a memcal to sever the EPROM from the resistor networks is pretty harmless. Is there agreement here? I mean, what are the odds you'll mess anything up? The reason I ask is it simplifies subsequent modification. I suppose we could put something together which would raise the whole intact MEMcal and allow a bypass cable or something. Mabye that's the way to go, have a PCB with a 50-pin socket on the bottom, and a 50-pin header on top. Just remap the EPROM-portion (28-pins) to a secondary header alongside where you could snap a ribbon cable. It could even be oversized at the cable (34-pin) to allow standard-sized ribbon cable conectors without shaving.

That being said, subject to disagreement or revision as aforementioned, picture the following:

At the ECM, the resistor networks plugged in by themselves. Next to them, an IDE socket (34-pin shaved down) is plugged in.

Option 1) The IDE socket is the bottom half of the EPROM half of your original MEMCAL. No changes from stock other than the memcal is a 2-piece job now.

Option 2) The IDE socket is attached to the bottom of a PCB. On the top of the PCB, you find a ZIF with your EPROM in it.

Option 3) The IDE socket is attached to a short ribbon cable of good quality, just long enough to allow the other end to be accessible. The socket has been shaved to fit a 28-pin header at the ECM as it needs to be, and it has been epoxied or otherwise rendered to hold together. On the other end of the ribbon cable is a 'header' connector, no need to shave this one, keep it at stock 30 or 34-pin. Into the remote 'header' goes the EPROM-bearing assembly as described in (1) or in (2).

I think options (1) and (2) will stick up a bit, but you could sandwich the ribbon in the cover plate with (3).

Anyways, I'm open to suggestions. Maybe I (or some of you) can post some PCB layouts which would be useful/helpful.

I soldered up something like that; took my memcal and cut it in half with a dremel. Unfortunately, it never did work for me. Of course, it was my "bad" memcal and the "bad" part might not have been the chip side, but the resistor network side. Live and learn *G*

I bought a protoboard at radio shack and used some headers to put 28 pins on it and cut down a floppy cable to 28. It ohmed out, but unfortunately never worked for me. Anyone have a spare memcal for TPI that works that they'll send me to test? ;-)

This thread has me about as confused as I ever expect to be...

(1) I'm definately interested in an extension cable to go from the ECU to the harness which plugs in to the ECU...Maybe 18" worth; flat cable, round, whatever...So I can re-locate the ECU where I can reach it conveniently...

(2) I'm not too hot about a MemCal extension cable...I've read too many reports about line noise and/or lag interfering with the data transfer/connection...

(3) I've already got a modified MemCal - ZIF socket to accept 27C128 or 29C256 EPROMS...No clearance problems; cover goes on over EPROM OK...

So, what exactly are we-all talking about here???

Cutting the MemCal in half; keeping the fail-safe chips, and plugging a custom board into the other half of the ECU header??? Custom board to accept an EPROM ZIF socket???

Or a board which the fail-safe *and* ZIF socket plug into, which itself then plugs into the ECU header???

...Argh...

That remote PROM mount - ribbon cable design, is the type of adapter that I thought you were talking about. That is the one that I would be interested in. The other setups are less useful in the over all picture if you ask me. They seemed to be a lot like what we are already using whether it be a flash PROM soldered directly onto the Memcal and using the adapter for the PROM burner, or using a ZIF socket soldered onto a Memcal and removing and replacing the PROM every time to make changes.

I like option 3. I think the crosstalk issues may be more of a problem than people think, though. If this is indeed possible, it would be the easiest to deal with since the original mounting location for the ECM can be retained and it would make making changes to the PROM a lot easier for us.

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

[This message has been edited by Matt87GTA (edited November 12, 2001).]

Will the picture shown clarify the proposal? Sorry for the hack-job mosaic, but I think the point should be pretty clear. I'm also concerned about crosstalk by the way.




[This message has been edited by Craig Moates (edited November 12, 2001).]

...I'm stumped...

...Sorry...

Think versatility. This route would allow at least 2 options:

1) ZIF or DIP socket dropping directly in the ECM in place of the EPROM half that has been cut off

2) ZIF or DIP socket at the end of a ribbon cable, attached to the ECM either through adapter (1) or through a shaved IDE ribbon connector.

Bottom lines:

1) I'd like a head count on who'd be interested in the custom PCB, which would simply be a ZIF on one side and an IDE socket on the other. This could go directly into the ECM header instead of the EPROM half, or it could go at the end of a ribbon equipped with a header. Very simple, just a row of 28 holes, 4 wide, spaced and interconnected. It'd be just like the carrier essentially, just EPROM-sized.
2) Any other ideas for a PCB? Feel free to submit a drawing. We could submit at least a couple desogns in with the minimum order and they should fit on the layout.
3) Any 'minimum order' parts folks would like to pick up, such as ZIF sockets or header connectors and such? Could save on some shipping. I was planning to order some from Jameco and maybe Digikey.

I'm in!

Well, I like this ribbon cable setup, like I stated before.

I already have an extra couple of ZIFs, so I would only be in for a ribbon, pcbs, header, and IDE connector blocks - just enough to construct the cable with an open pcb on one end to put a ZIF on, and an adapter that interfaces with the Memcal socket of the ECM on the other.

I think we need to think of some way of shielding this cable as well if we expect to have any success. I am aware of a foil like tape that GM puts on some of it's wiring for things such as Air Bags and ABS systems to ensure that they do not have problems engaging when they shouldn't from crosstalk (definately a good idea for the Airbags, don't ya think??!). I think this remote mount just might work as long as we keep the cable as short as possible, route it carefully (avoid sources of crosstalk as much as possible), and get a hold of some of that tape to wrap around the ribbon cable. I guess we really won't know until one of us tries!!

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

[This message has been edited by Matt87GTA (edited November 13, 2001).]

BTW, nice artwork Craig!!

Count me in

I'd be interested. I have a problem with opens between my ZIF and the header. I'm always resoldering it. This would definitely be better.

I've tried similiar things only to give up on them.
Currently, I've had to trim my DS ribbon down to 6" to get rid of RF noise.

On the syclones they have some remote *selectable* eprom stuff that seems to work, and they limit the ribbon to about 12" as I recall.

The secondary side of the ignition generates a huge amount of RF noise. I'd bet in part the coil near plug stuff is to min RF.

Has anyone tried using a cable with twice as many lines and grounding every other line, like the ATA/100 HD cables do for noise suppresion?

I believe the reason you can't extend the prom is NOT interferance but signal degradation.

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86 Camaro Sport
LT1 Induction
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project
Moderator at SE ThirdGen

How about an ECU extension??? I'm thinking the 7165 ECU, with it's two harness cables...Maybe an 18" extension...

I've been trying to do this for a couple months, but ruined one ECU header and screwed up another...(Them dang wires is too small for these eyes!)...

those work, I have used a 3' long extension to put the ecm under the passenger seat.
Also, makes tieing into the harness a no brainer, and you don't chop up the oem one experimenting.

You can buy the headers from
GMP Parts Company
(916) 685-1055
also about anything Weather pack related. Though best to buy quantity when possible. On terminals like for the ecm I get them in lots of 100. You'd be surprised how many you can use <g>..

The problems are more than likely going to come from both. But the noise has got to be the larger of the problems with the distances we are talking about here.....

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

Anyone remember a PROM selector called PROMPAC? It would seem to me this would be the way to go. It would certainly solve alot of problems as far as chip access and the ability to test multiple chips would be pretty handy. I have a brand new unit unused, guy said it would work on TPI computers, only problem was it was for the 85 TPI computers which used the 2732 chips. Still have it packed away in a box, haven't found it since I moved.
Anyone know if the company who made it is still in business? Gotta dig it out, still got all the documentation on it.


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91 Formula
305 TPI T-56 tranny
Spohn Torque Arm
Eibach Pro lines and Tokico Illuminas all around

I seem to remember seeing something similar advertised recently (Jegs? Summit?). It had a switch that you could slide to change between " full power", " Valet" etc. So how did they shield it? How long is their cable? And did it even work????



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86 406

Usually not very well.
The better switchers, mount the bigger eprom right by the ecm, and have the cable for the switching as the extension piece.

I called them today; they have the headers, but unfortunately they have a $100.00 minimum order price for an order...

The gentleman I talked to suggested getting a junkyard ECU and desoldering etc...

The least I can find hereabouts for a good junkyard ECU with the two-connector header is $35 (they don't sell wasted ECUs).

Somehow, I don't think I'll ever use $100 worth of these headers...

...But Thanks anyway, Grumpy!