In what way is it a DSP, as distinguished from a general-purpose machine?

Jerry

Thanks David and all,

Finally my code is ready and working. I realized the importance of NOP
instruction primarily as I was using single port data RAM.

Regards
Bharat

I was once "accused" of padding a double-precision-add routine with ADD #0. The astute accuser removed it and the routine passed his tests. The command was actually add-with-carry, and his tests didn't reach a case with Carry set.

Jerry

"dvsarwate" <dvsarwate@yahoo.com> wrote in message 
news:1357e75d-1ea5-4437-a136-a13e6be46ad0@v31g2000vbs.googlegroups.com...
> That being said, my favorite one-instruction
> computer has only the machine instruction
> DWIM:  Do What I Mean

Another instruction that helps with debugging (although no
in a single instruction CPU) is ..

If X should have been 3, then don't come from Y.

On 10/02/2011 02:21, bharat pathak wrote:
> Hello,
>
>       I am trying to implement a micro DSP with only 8 instruction
>       set. Can you help me with what should be the bare minimum set
>       required which will cater to most of the applications? FIR, IIR,
>       interpolation, decimation.
>
>       Forget about FFT for time being, as I am implementing a simple
>       MAC. Maybe even adaptive filtering could be skipped to begin
>       with.
>
>       Also is NOP instruction useful? What should the engine do when
>       NOP instruction comes? Do I need to hold on to the accumulator
>       value (keep recirculating the same?).
>

NOPs are always useful for timing, and they can make your implementation 
easier if you have pipelined instructions.

They are easily synthesised with other instructions that you might 
already have, such as ADD #0, AND #0xFF, etc., or a relative jump to the 
following instruction.

If you have no other constraints, why not make the instructions FIR, IIR, interpolation and decimation leaving four opcodes for other functions?  

Do you have any other constraints? 

Rick

On Feb 9, 8:41&#4294967295;pm, "Phil Martel" <pomar...@comcast.net> wrote:

>
> One instruction is sufficient for universal computation see
>http://en.wikipedia.org/wiki/One_instruction_set_computer
>however, for a DSP
> it's more a question of what set of operations allows you to implement some
> set of algorithms such as FIR efficiently.

It's like the result in Boolean algebra that any
logic function can be synthesized using only
two-input NAND gates (or only two-input NOR
gates) but having more types of gates available
allows for more efficient implementations.

That being said, my favorite one-instruction
computer has only the machine instruction

DWIM:  Do What I Mean

--Dilip Sarwate

"glen herrmannsfeldt"  wrote in message 
news:iivhj2$922$4@news.eternal-september.org...

bharat pathak <bharat@n_o_s_p_a_m.arithos.com> wrote:

>     I am trying to implement a micro DSP with only 8 instruction
>     set. Can you help me with what should be the bare minimum set
>     required which will cater to most of the applications? FIR, IIR,
>     interpolation, decimation.

I believe Knuth has a suggestion for a two instruction machine
as a possible minimum.  Eight should be plenty.  I would look
at the PDP-8 as an example of a minimal instruction set.

-- glen

One instruction is sufficient for universal computation see 
http://en.wikipedia.org/wiki/One_instruction_set_computer however, for a DSP 
it's more a question of what set of operations allows you to implement some 
set of algorithms such as FIR efficiently

   Best wishes,
   --Phil Martel 

bharat pathak <bharat@n_o_s_p_a_m.arithos.com> wrote:
 
>     I am trying to implement a micro DSP with only 8 instruction
>     set. Can you help me with what should be the bare minimum set
>     required which will cater to most of the applications? FIR, IIR,
>     interpolation, decimation.

I believe Knuth has a suggestion for a two instruction machine
as a possible minimum.  Eight should be plenty.  I would look
at the PDP-8 as an example of a minimal instruction set.

-- glen

Hello,

     I am trying to implement a micro DSP with only 8 instruction
     set. Can you help me with what should be the bare minimum set
     required which will cater to most of the applications? FIR, IIR,
     interpolation, decimation.

     Forget about FFT for time being, as I am implementing a simple
     MAC. Maybe even adaptive filtering could be skipped to begin 
     with.

     Also is NOP instruction useful? What should the engine do when
     NOP instruction comes? Do I need to hold on to the accumulator 
     value (keep recirculating the same?).

Regards
Bharat