Very urgent plz

i hav to interface memory (1k i.e 10 pins + control lines )
LCD ( 7 pins)
Keyboard (7 pins)
90 relays (using 3 latches octal using array model so
8+3)
rs232 interface(2 pins)


so i want a controller which is useful in project and at the same time debugger availabl locally

plz reply me soon...........................................

you need an 40 pin micro.

check here:
**broken link removed**

you shod find exsactly what you need there

reply

This must be a very large project

OK, first important question is: what type of Micro you want to use ?
If it's PIC, then you don't need external paralel memory. If 8051 then I can't help you.

PIC's have great support from Microchip and from Forum's like this one, try reading "Sticky: Newcommers, please read! (PIC regarded) Upd. 4", it has some valuable info for beginners.

If the project is really Big, use 16F877 or 18F4x20 (where x 3-6).
Also, try to use Microchips port expanders, they use serial bus (I2C or SPI) to bring you more outputs, this could be better than latches.

Do you really need a full 10 pin memory interface? There are some huge (1 meg) SPI & I2C eeproms out there. Also the later PICs like PIC18F4620 have like 64k of ROM space which may handle your memory needs on-chip.

You're not talking about storing programs off-chip, are you?

That's a crapload of relays. You never told us your app but you might want to review whether relays are the best choice. They're going to likely require an external diode and transistor for each one. Relays are generally expensive and difficult to mount. A mosfet or thyristor array might be simpler, smaller, cheaper, and easier to assemble, especially when you're talking about 90 of them.