Double size chip map switch

[Adhamkhe]

Hi is there a way to switch between 2 stacked bins on a double sized chip? (2 files 256 on a 512 chip)

[olafu]

512k chip has one more address line compared to 256k chip. You need to switch this address line to 0V or 5V to change between upper or lower memory. It's not good to switch in running ECU, so i recommend to turn ignition off and wait 10 seconds before switching memory. You can find more detailed instructions when you search "EPROM switcher" from e.g. Google.
With some kind of latching you can switch memory in live ecu, if differences between files are limited to map data only. Depending on the chip and without any timing and/or latch circuit it's possible to change memory block during read, in this case CPU can read corrupted data.

[Adhamkhe]

Thanks a lot. I will try that tomorrow

[Adhamkhe]

So pin number 1 (vpp programming voltage on 27c256) is (a15. Address 15 on 27c512. ) is that what you recommend using as a switched 5v ?

[olafu]

Yes. Lift this pin up from socket. Use short wires as possible. And 5V or 0V from chip socket. Use 1k pull-up, if you don't have on-on switch.

[Adhamkhe]

only up

Hi is there a way to switch between 2 stacked bins on a double sized chip? (2 files 256 on a 512 chip)

Chips typically have memory addresses associated with different locations within the chip. You may need to specify the memory address or range of addresses associated with each bin to access the data stored in them.

Hi my friend. 7ff0 is the end of the first file .
I got a chip to try tomorrow on 173 ecu. Trying pin 1 and using an on on switch as advised by olafu.
Do you think that's ok for that address? Using chip st m27c512
Thanks for your reply