By: David Hess (firstname.lastname@example.org), March 8, 2013 11:24 am
Room: Moderated Discussions
gallier2 (email@example.com) on March 8, 2013 1:43 am wrote:
> David Hess (firstname.lastname@example.org) on March 7, 2013 11:22 pm wrote:
> > I have seen the 8 and 16 bit vendors make the same mistake with product segmentation if it a mistake.
> > Invariably I am always looking for as much SRAM as possible in the most convenient package. Sometimes
> > they accidentally break the mold and provide a product that becomes a classic and ends up being
> > used everywhere and driving new design wins with other parts like the old PIC 16C84 although at
> > the time, they were relatively expensive so that may not be a good example.
> Atmel AVR, basically eliminating whole families of µControllers (where have 8051, Z8,
> 68750 gone?) thanks to its excellent flash programmability. I remember when we considered
> PIC 16C84, AVR was just starting, we switched instantly. The AVR were 4 times faster,
> 4 times cheaper and were quickly available from 8 pin to 144 pin PLCC.
The performance gap was pretty big. I imagine closing that would have required a Pentium Pro like instruction translation scheme which the economics could not support and of course the existing manufacturers were hardly going to cannibalize their older product lines with a new RISC like design even if that is what they should have done. Maybe Motorola's Coldfire was an exception? The older processors used multiphase clocks or the equivalent internally without pipelining so the instruction execution rate was a fixed fraction of the clock rate. I never liked the 8051 but the Z8 series tempted me many times.
We were already using PIC after a switch from 68HC11 because of supply problems when AVR came out so switching again (from PIC to AVR) would have meant giving up what we were already using and there just was not enough advantage in doing so even though I would have prefered the AVR ISA. I am between project series now so switching is a possibility whether to AVR or ARM or something else but switching from one 8 bit to another 8 bit seems like wasted effort so ARM gets a lot of the benefit of any doubt.
The 68HC811 had in circuit programming support, EEPROM, the perfect packaging, and great development support, but availability of it and the support ICs killed it for us. That was hardly a new problem with Motorola and just shows that availability trumps price, performance, memory size, and packaging every time. The only way to design around no stock is with some other product and usually a different manufacturer.