14 Sep
2002
14 Sep
'02
3:55 a.m.
Bob Shannon wrote:
No on-line docs, but I have full schematics for the
PDS-1. Not easily
scannable...
But to turn this into a FPGA processor, a MAJOR redesign is needed. The
current design is highly dependant
on RC pulse shaping networks, one-shots, etc. The memory timing is very
core-specific, and some modifications
were needed for it to use modern semiconductor memory.
So to implement this on a chip, a new CPU needs to be designed just
about from the ground up, using modern design methods. About all you
really need is the instruction set information, the original schematics
are not much of a help here due to the design methods used by Imlac back
in 1968 and 1969.
Its really amazing to see how much engineers did not know back then. Its
also amazing that the Imlac worked at all, given how it was implemented
back then.
It is not that they did not know better, that is all they had to work with.
Mind you cost cutting often did not help any computer product.The real problem
is the Imlac is VECTOR display. Finding a new CRT would be a problem with the
original design. A raster scan display design could be used but then you
need to buffer the display correctly to have unrefreshed data fade off the screen.