How many of you like HP41C calculators?

From: vance_at_neurotica.com <(vance_at_neurotica.com)>
Date: Wed Nov 19 00:31:05 2003

On Tue, 18 Nov 2003, Eric Smith wrote:

> > Strictly-speaking, Microchip's PICs are NOT COMPUTERS. Of course I
> > don't make that distinction when working with them.
>
> I strongly disagree with any definition of "computer" that *requires*
> the machine to have a von Neumann architecture. In fact, most people do
> not even define computer to necessarily be of the stored program
> variety, although I'm willing to accept such a definition.
>
> The earliest PICs (eg. the NMOS PIC1654 from General Instruments in the
> 1970s, and the CMOS PIC16C54 from Microchip in the 1980s) do have a
> strict Harvard architecture. Program memory is in an entirely separate
> address space from data memory, and they have no way for the program to
> be able to read or write an arbitrary location in program memory.
> Table lookup works because there is a way to do a branch to a computed
> address (though it is limited to only a portion of the program address
> space), and there is a single instruction that loads the accumulator
> with a constant and returns (RETLW).
>
> More recent PICs (late 1990s to present) have used a modified Harvard
> architecture. They have added means for the program to read arbitrary
> locations in program memory, and in flash memory based parts, to write
> to program memory.

I don't even think it would be impossible to build a wide-purpose computer
around an AD SHARC DSP, even.

Peace... Sridhar
Received on Wed Nov 19 2003 - 00:31:05 GMT