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Message
From: "Jim Dempsey" <tapedisk@a...>
Date: Thu, 13 Feb 2003 10:36:02 -0600
Subject: Re: [oc] Beyond Transmeta...
----- Original Message -----
Sent: Wednesday, February 12, 2003 4:23
PM
Subject: Re: [oc] Beyond
Transmeta...
>
> But, in difference to 'sims': it is
not necessary to keep the single
> identity for every bit while it is
traveling the system, is it ?
>
> bax
>
The techniques for optimizing the performance of
the system would
require the bits (or bit streams) to exist in
multiple places at once
and in different time states. A simple illustration
would be
aaaa = bbbb +
cccc
bbbb = aaaa + cccc
Becomes: (set to display in courier)
bbbb+
cccc+
aaaa+/
cccc+
bbbb/
Note that you cannot visualize bbbb as a whole
entity at all points
in time. In time state 3 the lsb of bbbb
transitions to new state
while the more significant bits of bbbb (of the
first use) have
yet to be used. There undoubtedly will be cases
where the bit
"consumption" rate of a bit stream longer than 1
clock tick. In this
case if the input variable is recomputed elsewhere
then the
first use stream is conceptualized
as producing a loop. This
is too hard to diagram here in text
glyphs.
Conceptually, if a "function" block were to use a
variable at a particular
time state it would always clock in one bit per clock. Internally it can
consume (use) the
bits at a longer time interval (e.g. one bit every
other clock). You
can view this as a serial FIFO where input and
output are at
different clock frequencies.
The implementation would not use a FIFO inside each
function block.
Instead. The bit stream variables, at any one
time, can live at different
time states in multiple locations of the device.
Example:
(set to display in courier)
bbbbbbb
b
bbb
In the above if the bit stream of bbbbbbb were
forked and if the leading
bit of the upper and lower streams were used at the
same time in
the device then the lower use is as the state of
bbbbbbb was two time
states earlier. If the loop is longer than the
width of bbbbbbb then it
becomes possible to use an earlier state of bbbbbbb
even after a
later state of bbbbbbb was completely modified. The
delay loops
and/or ersatz FIFOs are an integral part of the
dynamic wiring of the
device.
This is quite a departure from programming
languages such as C++,
FORTRAN, etc. Initial uses of the device would make
use of cross
compilers where you start your programming
experience using something
familiar. Later on a new language would evolve
beginning with some
obtuse precompiler
statements/directives.
I envision that the ideal programming tool would be
a visual tool that
resemble something like needlepoint that is
"performed" on a time domain
scroll (player piano like). The width of the roll
is respective of the size
of the device BSPLD or whatever acronym suits you
best. If you use a
smaller device than optimally (performance wise)
the length of the roll
extends (i.e. the computation takes longer). You
likely would perform
the needlepointing on an abstraction pane and a
separate pane would
be drawn to illustrate the utilization of the
target device.
Jim Dempsey
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