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Memory Mapped Vs I/O Mapped Vs others

Started by karthikbg December 17, 2006
Hi,

What is the actual difference between the following :
"Memory Mapped"  Vs  " I/O Mapped"   Vs "Memory Mapped I/O"  Vs " I/O
Mapped Memory"   ?

Kindly tell me their actual definitions/meanings .
Further, Let me know some best conditions whereit should be used and
other scenarios where it should not be used.

Need some clarifications / links / docs.

Thx in advans,
Karthik Balaguru

Hi,

What is the actual difference between the following :
"Memory Mapped"  Vs  " I/O Mapped"   Vs "Memory Mapped I/O"  Vs " I/O
Mapped Memory"   ?

Kindly tell me their actual definitions/meanings .
Further, Let me know some best conditions whereit should be used and
other scenarios where it should not be used.

Need some clarifications / links / docs.

Thx in advans,
Karthik Balaguru

karthikbg wrote:
> What is the actual difference between the following :
The textbook for your course should provide much of the information you need to write this homework assignment. Your professor will doubtless be able to recommend other sources of information equally instructive.
karthikbg wrote:

>Hi, > >What is the actual difference between the following : >"Memory Mapped" Vs " I/O Mapped" Vs "Memory Mapped I/O" Vs " I/O >Mapped Memory" ? > >Kindly tell me their actual definitions/meanings .
Some processors provide seperate memory and I/O address spaces by including additional control bus bit(s). For example, in addition to a read/write bit there may also be a memory/I/O bit. The hardware designer uses the latter, when available, to map memory and I/O devices to the memory and I/O spaces, as desired. When there is no seperate I/O space (or even when there is), I/O devices are (or may be) mapped to the memory space leading to the term "memory mapped I/O." "I/O mapped memory" is rare. I know of no processor that provides only an I/O space, but I suppose that one could map a specialized memory device such as a EEPROM to an I/O space, although I've never seen it done.
>Further, Let me know some best conditions whereit should be used and >other scenarios where it should not be used.
I/O mapping can be used only if one's processor supports if and may be used to simplify one's hardware design. The Zilog Z80, for example, provides I/O mapping. Its address bus is 16 bits wide but only the lower 8 bits are valid during I/O space accesses. This can be used to the designer's advantage because it simplifies I/O address decoding.
>Need some clarifications / links / docs. > >Thx in advans, >Karthik Balaguru
-- ======================================================================== Michael Kesti | "And like, one and one don't make | two, one and one make one." mrkesti at hotmail dot com | - The Who, Bargain
karthikbg <karthik.balaguru@lntinfotech.com> wrote:
> Kindly tell me their actual definitions/meanings .
Kindly tell your prof you're going to fail his class. pete -- pete@fenelon.com "he just stuck to buying beer and pointing at other stuff"
Himanshu Chauhan <hs.chauhan@gmail.com> wrote:
> Haven't you gone through Page 388 (Chapter 11) of M. Morris Mano?
Crikey, is that book still going? It was the freshman digital electronics text I used over 20 years ago ;P pete -- pete@fenelon.com "he just stuck to buying beer and pointing at other stuff"
Pete Fenelon wrote:

> > Haven't you gone through Page 388 (Chapter 11) of M. Morris Mano? > > Crikey, is that book still going? It was the freshman digital > electronics text I used over 20 years ago ;P
Yes! Amazing, eh? [pulls copy off shelf...] I think it is still only in its 3rd edition, revised in 1993; first publication in 1976. Mind you, I'm a bit curious what exactly they revised in 1993, since it still reads like a book from the mid-1980s AT BEST.
larwe <zwsdotcom@gmail.com> wrote:
>> Crikey, is that book still going? It was the freshman digital >> electronics text I used over 20 years ago ;P > > Yes! Amazing, eh? [pulls copy off shelf...] I think it is still only in > its 3rd edition, revised in 1993; first publication in 1976. Mind you, > I'm a bit curious what exactly they revised in 1993, since it still > reads like a book from the mid-1980s AT BEST.
When did the 1st ed of Horowitz and Hill come out? Must've been around then.... An infinitely better book than Mano, or the dreadful Senturia and Wedlock which totally soured me on analogue electronics for life! Of course, we were taught analogue by the EE department and digital by the CS dep't so using the same book was obviously out of the question ;) pete -- pete@fenelon.com "he just stuck to buying beer and pointing at other stuff"
Pete Fenelon wrote:
> Crikey, is that book still going? It was the freshman digital > electronics text I used over 20 years ago ;P
But you still started with that book, right? And now your experience builds on that book, ain't it? --Himanshu
Michael R. Kesti wrote:
> karthikbg wrote:
<snip>
> I/O mapping can be used only if one's processor supports if and may be used > to simplify one's hardware design. The Zilog Z80, for example, provides I/O > mapping. Its address bus is 16 bits wide but only the lower 8 bits are valid > during I/O space accesses. This can be used to the designer's advantage > because it simplifies I/O address decoding. >
This is a common misconception about the Z80. The Z80 has two types of IO instructions, using 8 bit addresses or 16 bit addresses. the 16 bit address is in registers BC. I don't have my docs handy, so I can't give the exact syntax here. Mixing the two types is problematic, since IO address decoding normally is either 8 bit or 16 bit, giving 256 mirrors in IO spave :>(
>> Need some clarifications / links / docs. >> >> Thx in advans, >> Karthik Balaguru >
Regards, Hans