On Mon, 4 Jan 2021 12:03:27 -0000 (UTC), Martin Gregorie
 declaimed the following:


>No problem. At least this made me look at the PIC architecture and
>discover that it doesn't handle signed integers - I think its the only
>system I've know of at that doesn't, so I didn't realise at first that
>this limitation is in the hardware rather than a feature of the BASIC
>compiler.

 The base BS2 uses a PIC16C57c (the BS2e, sx, p24/p40, pe, and px all
used variants of Ubicom chips -- given the lack of information online, I
suspect they were custom designed for Parallax alone -- ha! "The SX line of
microprocessors are produced by Ubicom, Parallax is the only authorized
distributor of the chips.")

 From the manual

"""
All BS2 models can interpret twos complement negative numbers correctly
in DEBUG and SEROUT instructions using formatters like SDEC (for
signed decimal). In calculations, however, it assumes that all values are
positive. This yields correct results with two’s complement negative
numbers for addition, subtraction, and multiplication, but not for division
"""


 Hmmm, Parallax finally released a Propeller 2 chip.
https://www.parallax.com/propeller-multicore-concept/ and appear to have
discontinued all BASIC Stamps (not a surprise -- last time I checked a BS2p
was around $70 while a Propeller Quickstart is only $40.

 Propellers are interesting chips... 8 simple cores running in lockstep;
each core has some internal RAM for programs (so it can be different code
in each core) written in assembler. The default mode is that the core is
loaded with a byte-code interpreter, and SPIN programs are read from
external memory. The P1 allowed one core at a time to access external
memory (in sequence); the new P2 apparently allows all 8 cores to do memory
I/O on each cycle.


--
 Wulfraed                 Dennis Lee Bieber         AF6VN
 wlfraed@ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/

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