Help me with using 2 28F400 memory chips on a board

[beyerch]

28F400 dual circuit?

Hi,

I have an application I work with that stores all of its data (operating program code and memory storage <data>) on an Intel 28F400 memory chip. I was thinking about a way to allow for me to hook up two memory chips to the board so that I could switch between the two chips in real time. Basically each chip would have the same program code, but different data that I would like to alternate to and from.

The circuit should have logic to NOT switch in the middle of a read or write operation. I'm pretty much new to this stuff so to me this is pretty hard; however, from what I have read it really should be a matter of putting the two memory components in parallel and just switching the Enable Lines to signify which chip is actually active. The catch is to check the lines to make sure notihing is active when switching.

Can anyone out there either help me out with a simple schematic or would someone be willing to do this for some $$$. I would really like to try this idea out so please help!

Thanks

Charles

 

[alphi]

Re: 28F400 dual circuit?

If posssible, use a MX29f800 to replace two f400,and this chip is from taiwan,and cheapest.

 

[beyerch]

Re: 28F400 dual circuit?

Thank you for the reply.

I have one MINOR issue with that suggestion however.

One of the things that my unit currently supports is flash reprogramming of the memory chip via a user interface. IF I use a larger chip and mask the addressing, it will render the reprogramming option useless.

I would like to retain all aspects of the operation of the project so i think i'm pretty much stuck with the chip i'm running.

That thought has crossed my mind however!

Thank You

Charles

 

[tlp71@hotmail.com]

Re: 28F400 dual circuit?

I THINK THAT the best way is to use or create two chip select and when you have to write the right device you can, if you don't have more chip select you can use a simple pld to create this using the address space.
Bye.
g,