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[MachineForth] Chuck's 25x and IBM's Blue Gene

Dirk Heise wrote:
> So, if there would be some cheap board with a Misc or Stack
> based CPU, or some consumer product i can rip such a beast
> off, i'd expect a much better match to the language. Is
> there really no such CPU on the market? I can make my own
> board if necessary, so the chip would suffice. Does anyone
> here have pointers? I can't spend a fortune, so it must be
> cost effective. Hobby for now. Maybe an FPGA based design.

X18 and 25x has the same instruction set as F21 but there
are only a few prototype F21.  But for evaluation purposes
the simulators and emulators run ROMs, provide 
various profiling and diagnostic capabilities for your
code, and come with built in MachineForths.

P21 has nearly the same instruction set, it does not have
@R+ !R+ and 2/ leaves two bits unchanged.  P21 has been
available since 94 for $25 in one of.  P21h has been
available since 95 for $40. Both have $100 kits or
you can make boards which basically require routing
chip select and address and data busses between chips.

X18 has stacks that are about as deep as F21 while P21
has very shallow stacks only 6/4 cells deep.  This 
makes P21 an excellent trainging machine.  If you
are used to the idea that C or Windows needs 
megabytes of stacks, and Forth only needs kilobytes
of stacks you can get used to the idea that
Forth only needs a few stack cells.  If you get
used to that the x18 and 25x will seem like they
have very large stacks.

P21 and F21 are different than x18 in having an 
extra bit on the stacks.  There are free emulators
and simulators, lots of example code in MachineForth 
and extensive tutorial information. This makes x18
simpler and a closer map to the ANS model.

You can also get Ting's CD with FPGA sources for
P8, P16, and P24, MachineForths, eForths, and
various older manuals.  If you like to play with
those you could roll your own P18 in FPGA.  There
is also John Rible's QSP16 and other people's
FPGA designs if you want to that route.  An old
P16 FPGA source is online.

> Anybody here who got a Misc design working at home, be it a
> stock CPU, an FPGA or whatever without being a full time
> chip designer?

Yes. P21 ceramic dips, P21 plastic dips, P21h PLCC,
and F21d CLCC variants as well as the simulators
and emulators.  No free complete x18 or 25x emulators
at the present time but that would take a few hours.
> And is iTVc still in operation?

Yes. They have other active projects.

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