27cxxx eprom switcher

Do not do this, because if you do, people could die.

If you want to change your car's ECU program, put it in the shop, up on the rack, pull out the old EPROM, plug in the new, presumably pre-tested, EPROM, test the new EPROM and its functions, THEN it could be safe to let the car down off the rack.

Switching the ECU program while running is suicide, which I'm not telling you not to do (see "Darwin Effect"), but it's terribly important to caution you against taking any innocent bystanders with you when you lose control of the car.

Tell the teacher, "I refuse to do this assignment because it endangers the life and limb of innocent people."

Good Luck! Rich

Ensure that you have a giant spike which is driven into the ground by explosives during the transfer period to ensure that your vehicle is safe during the transfer.

Ooh, sounds like fun...

You should be able to just switch the top address bit on a c256 to select which c128 image you're feeding to the ecu.

Ignore those worrywarts -- go for it. What's the worst that can happen, eh?

Have someone taking pictures, video -- from a distance.

And post them on

Sensibly now, Yes you can just switch the MSB on a 256, but I wouldn't advise doing it while the engine is running.You will probably crash the ECU, maybe damage the engine?. Absolutely no problem doing it with the engine off.... If the eprom just contains a map, and no CPU executables, then you could do it with the engine running ( your risk!) but you would need to synchronise the switch with some logic with the CPU. Put the switch input onto the D of a D type and clock it with one of the system clocks from the CPU.....

On a sunny day (Thu, 8 Feb 2007 07:01:33 +1030) it happened "mark krawczuk" wrote in :

Well, if it is just for yourself, solder 2 on top of each other and switch the OE lines (you'd have to peal of the bottom ones OE line from the board), and gate these with the board signal.

On a sunny day (Thu, 08 Feb 2007 06:15:57 GMT) it happened "Homer J Simpson" wrote in :

Way to dry after a carwash.

I did something very similar for a game that someone wanted to swap a lookup table during runtime. It has been a LONGGGGG time ago, but what I did was to use a latch to change the upper address line (swap banks) only during the rising edge of /CS. That way I knew the CPU was doing something else and, in this case, just swapping the lookup table didn't blow anything up.

Jim