> Someone recently informed me that Motorola
> and Zilog both have low cost processors (< $1.00 US).

Zilog offer a number of processors in their Z8 and Z8+ ranges.

Some are extremely good value for money - arguably better than anything else
available at similar cost.
Some are under $1US and for a little over $1US (about $1.20?) they have the
Z8E001  with the new Z8+ core.
This has a 1uS cycle time for ALL instructions, very good addressing modes,
real stacks, hardware PWM, several 8 and 16 bit timers depending on PWM use
(eg 16 bit hardware PWM plus a single independent 16 bit autoreload timer),
1 comparator and more. A nice device. For one project I could not find
anything else that would do the job without paying much more.

Availability will have to be determined in today's climate - semiconductor
shortages are bad and getting worse for everyone..

Intro tools are excellent. There is a basic REAL emulator for $100. This
does NOT have a realtime trace buffer but allows compile, download and run
to in circuit target from a PC, multiple breakpoints, single step, view all
memory and registers etc. Assembler and IDE is free. It is the best value
intro kit I have seen (including PIC, AVR, Scenix). For many purposes this
is all the tool you will need for development. I think they have improved
things somewhat since Dave van Horn's experiences - seems so anyway. They
also have "real" ICE boxes with realtime trace buffers etc but I have no
experience of these.

I would rate the Z8 as a nicer processor to use than PIC which is not to say
that it replaces PIC - just that the linear address space, wider instruction
set etc make it less of a shock to get going on. Little things like real
stacks, not having to do a complex context saving dance on interupt and more
really helps. It still has some unique concepts top come to grips with in
order to wring best code efficiency from it - you can effectively address
memory with 4, 8 or 12 bit addressing depending on what you are trying to do
and there are page pointers if required.

Heresy - I'd say the AVR family is nicer BUT not as cheap for bottom end
applications.
.
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