How to use external EPROM on MC68HC705

[dragomil]

(Thread split from 16Bit)

Okay! Many thanks.

Maybe they built 68000 with integrated silica gel.

My other interest is how to bypass the internel rom of a mc68hc705, and use it with external eproms.

The book does not show me how to do it.

dragomil

Alban (Moderator) split the thread to address new question on other subject (HC705).

Message Edited by Alban on 02-02-2006 01:54 PM

[booleangeneral]

Hello !

Try to get an old EVM ( Evaluation module ) manual of the MC68HC705C8 and you´ll see how to do it. Any C8 can be "bus opened" and have the usual 6800 lines R/W , E , Address bus and Data Bus, but be aware that it is not an easy task. It takes a lot of external hardware like latches, gates, etc.

Greetings from Buenos Aires, Argentina !!!

[Nabla69]

Hi Drago,

I tried to take a datasheet for an example : HC705P9.
It doesn't look like you have access to the internal bus.

If you have control over the internal software, I imagine you can program your EPROM/OTPROM to work with the SIOP (=SPI) to address external memory.

Alvin.