The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: "Frank Bemelman"
Subject: Re: Philips XA architecture design
Date: Mon, 28 Oct 2002 22:46:35 +0100
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
Organization: EuroNet Internet
NNTP-Posting-Date: 28 Oct 2002 20:46:41 GMT
"Tim Kortekaas" schreef in bericht
> I posted a question about designing a little dev board for the Philips
> XA architecture. But I'm still confused with something. If the processor
> is in 16 bit mode, A0 isn't used because the processor fetches the data
> in byte-pairs. But when I look at the specifications of a (for instance)
> M27C1024 EPROM (1 MB, 64k x 16, STMicroelectronics) it has 16
> adresslines (duh).
> In my previous post (tnx for replies Frank and Paul) someone mentioned
> the EPROM puts the data of the even and next odd adresses on the 16 bits
> bus. But the EPROM has 64k addresses of 16bit words.
> Do you get the confusion ?
The processor will see the eprom as 128K adresses, each adress holding
one single byte of information. The eprom delivers it in 2 bytes portions
at a time, over its 16 bit databus.
> Do I have to connect A0-15 of the EPROM to A1-A16 of the
> microcontroller? Maybe I am making just a simple wrong step in the
> beginning of the problem solving...
Yes, and you will have 128 Kbytes of program memory that way.
> And about the programming, this isn't clear to me either. The output of
> my compiler (standard compiler from the IC25 databook CD) is in Intel
> Hex File format. In the beginning of a line in this file stands the
> address of the data that has to be written in the EPROM. But it are 8bit
> numbers. Isn't every address of the EPROM filled half then?
I think you are confused by the '16bit' aspect of this processor.
The number of bits is not important in respect to the memory - the memory
is a range of adresses, each adress holding 1 byte. Physically, the memory
can have an 8 bit or 16 bit adressbus, but for the software this makes
It is similar to PC's, the pentium is 32bits, the memory-databus is
32bits wide, an long integer is 4 bytes, but occupies 4 adresses of
1 byte. If the long integers are aligned properly (and the compiler
will do that often by default) it takes only 1 memory cycle to get
that long integer, and it can be stuffed into the accumulator in
one single move.
(remove 'x' & .invalid when sending email)
> I have lots experience with the 80c51 based series of Philips, but none
> with the XA or other 16bit ucontrollers.
> Tim Kortekaas
> To reach me by email, remove the obvious...
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup