Thanks for your answer, Andy. But there are still questions:
On Mon, 1 Jun 1998, Andy Kunz wrote:

>> Topic: address decoder for external progr. mem.- Do I need
           one ?

> No, you don't if you use a 64K x 16 memory chip.  You DO need the address
> latch.  You DO need to do something to generate the program timing pulse,
> though.
> To get around this, I use battery-backed SRAM (CY7C1021).  Infinite
> re-writes, and let's me have more data memory to buffer stuff.

Unfortunately I already had to order the devices and I found the AMD flash
memory (with 45ns access) for optimal in my case. This is an 128K x 8
chip. I have also ordered the latches.
How does the address decoder look like for this chip (or in general for
8bit devices on a 16bit port) and what does it perform ?


>> Topic: Programming voltage necessary?

> No, I presume you will have your program to use the RS-232 in the internal
> EPROM.  You shouldn't be reprogramming this.

Since I use both program memories can I presume that I have to run the PIC
in "extended microcontroller mode"? Or is it also possible to have the
RS232 setup program in external memory, without using any internal mem.?


>>   c) I'm going to use MPSIM. How can I setup the programming transfer?
> Huh?
** Anybody else an idea? **


>>   d) In the datasheet there are shown some resistors to use the serial
>>      port pins also for other purposes (when not programming). Can I use
>>      4.7 KOhm for that?

> That really depends on the rest of your circuit.

Sorry, I presumed TTL I/O devices, but didn't write it. Is 4.7KOhm then
OK ?

Andreas Dante