question about cpu

[jidan]

can anyone tell me that how we identify that cpu is 8 bit or 16 bit or n bit

 

[kubeek]

One way would be reading the datasheet.

 

[jidan]

One way would be reading the datasheet.

ok I know but can you tell me another way

 

[MrAl]

Hi,

You mean like by counting the pins or something, or by examining the in-circuit electrical signals?

You can not tell by counting the pins.

Without examining the signals you'd have to look at the die and know something about die architecture.

Examining the signals you'd have to be able to decode the data buss.

By examining the circuit board (mother board) you might be able to tell from the other chip types but that's tricky.

 

[jidan]

Hi,

You mean like by counting the pins or something, or by examining the in-circuit electrical signals?

You can not tell by counting the pins.

Without examining the signals you'd have to look at the die and know something about die architecture.

Examining the signals you'd have to be able to decode the data buss.

By examining the circuit board (mother board) you might be able to tell from the other chip types but that's tricky.

ok I am asking you simple question design 8 bit controller so what will you do i think you need specification how you will decide what specification need for your controller controller same work i am doing I am looking specification for controller

 

[ronsimpson]

look at the memory. 256x8 or 512x16.

 

[kubeek]

ok I am asking you simple question design 8 bit controller so what will you do i think you need specification how you will decide what specification need for your controller controller same work i am doing I am looking specification for controller

I cannot see a single question mark, so that does not qualify as a question. After reading it four times I am starting to have some idea what you meant, but still it is a bit too mixed up together. Could you rephrase that so that we know what exactly you are asking?

Basic thing is that 8 bit cpu can do operations on 8bit chunks of data. Like adding two 8bit numbers or doing an OR on two 8bit numbers.
On the other hand most 8bit micorocontrollers will have much more than just 256 bytes of memory (that 8 bits allow) so the address could be for example 16bit, but you would need two operations to say increment that adress, since the cpu can only process 8 bits at a time.

 

[ronsimpson]

I cannot see a single question mark, so that does not qualify as a question. After reading it four times I am starting to have some idea what you meant, but still it is a bit too mixed up together. Could you rephrase that so that we know what exactly you are asking?

Basic thing is that 8 bit cpu can do operations on 8bit chunks of data. Like adding two 8bit numbers or doing an OR on two 8bit numbers.
On the other hand most 8bit micorocontrollers will have much more than just 256 bytes of memory (that 8 bits allow) so the address could be for example 16bit, but you would need two operations to say increment that adress, since the cpu can only process 8 bits at a time.

Many 8 bit CPUs have 16 bit address pointers and data pointers. These pointers can be incremented (a=a+1) with out going through the CPU. Example: get data at (pointer) and pointer=pointer+1. This is one instruction.

 

[Ian Rogers]

It seems as if designing an 8 bit microcontroller is the "in" question at the moment....

You need to re-write this so we can understand

ok I am asking you simple question design 8 bit controller so what will you do i think you need specification how you will decide what specification need for your controller controller same work i am doing I am looking specification for controller

I read it thus..

Ok! I am asking you simple question!
Design 8 bit controller. So! What will you do?
I think you need specification!
How you will decide what specification need for your controller?
Controller same work I am doing...
I am looking specification for controller...

Even then I'm struggling!!

 

[ronsimpson]

More questions:
Does this thing have to work? OR is it like a "block diagram".
How much detail do you need?

Have you looked at CPUs data sheet to see how companies make them?

 

[jidan]

I am sorry for my bad English. can you tell me, what is difference between data bit and instruction bit?

 

[Ian Rogers]

I am sorry for my bad English. can you tell me, what is difference between data bit and instruction bit?

You have no need to apologize.... We are just trying to get the proper requirements so we can help you!!

Instructions (bytes) are located in code memory (Flash nowadays) and data bytes are located in sram or EEprom

Instructions are used to tell the CPU what to do with the data...

 

[jidan]

You have no need to apologize.... We are just trying to get the proper requirements so we can help you!!

Instructions (bytes) are located in code memory (Flash nowadays) and data bytes are located in sram or EEprom

Instructions are used to tell the CPU what to do with the data...

what is data path and instruction path in micro controller

 

[kubeek]

Lets imagine an istruction that sais add A to B and store it in A.
Data path are the wires that connect A and B to the ALU. Instruction path are the wires that connect the instruction (stored in some place) to the control unit.
Try reading this, it seems to explain a bit more https://minnie.tuhs.org/CompArch/Tutes/week03.html

 

[KeepItSimpleStupid]

Using simple terms of instruction space and data space, ispace and dspace for short. dspace changes; this is basically RAM; Instruction space doesn't It's typically accessed by the program counter and has fixed values (e.g ROM, EPROM, EEPROM but can be RAM). The categories are not engraved in stone.

In larger computers, there could be many Ispaces and dspaces. The OS operates in one and each program operates in another. ispace and dspace could be RAM in a larger computer, but if the program counter ended up accessing dspace that would be considered an access violation. The Program Counter is only allowed in ispace.

The common cause of the blue screen of death - there was no protection (hardware layer) between programs and the operating system.

Instruction path - anything that has to do with modification of the program counter

Data path - things like adding, subtracting, getting a value from a memory location.