Hi Dave! Thanks! We did convert
the S-100 68K V2 prototype to the PLCC and although it
worked there was a lot of push back on the design. I
think a lot of builders just like the DIP-64 package I
guess. Good point on the 16 bit Flash though.
The major cause of the recent delay
of the S-100 68K CPU V3 board is I completely reworked
the PCB layout. Originally the chips were vertically
oriented and it drove the trace route optimizer nuts.
I reoriented everything to horizontal and it literally
cut the number of vias in half and reduced trace
length by a large percentage. Probably I should have
done that at the beginning though but I was trying to
retain as much compatibility with the original design
as possible but that’s fallen away too.
Once we get the S-100 68K CPU board
out though I do have plans to add in a MC68020 CPU
shim board based on a C’T Projekt design. I forget
the name at the moment but have all the plans here at
It seems that of all the S-100
boards, the CPU designs are the most difficult and
cause the most rework. That’s the bulk of the backlog
at the moment: S-100 80286 CPU, S-100 68K V3, S-100
6502 V2, S-100 80386 CPU + SRAM, etc. It’s a bit like
a python that just ate 4 goats in a row. It is taking
a while for all the lumps to work through the system
Thanks and have a nice day!
As another thought - why not
substitute a 68 pin PLCC version of the 68K (MC68000FN12) and an AT29C1024 16 bit
44pin PLCC for the eeprom. These would drastically
reduce the density on the board an might make the
trace routing simpler. The 16 bit eeprom would make
the programming simpler as well - just a thought. I
have both in hand so it would not be a problem and
they are reasonably priced as well.
On Sunday, February 24, 2013 2:32:18 PM UTC-6, yoda
How close are we on the S-100
68K??? There is a lot of pent up demand for that
board - especially me as I work on the other 68xxx
system - I am trying to write platform independent
code and would like to test it on the new 68K board
On Sunday, February 24, 2013 11:17:26 AM UTC-6,
Well I was hoping to get
the S-100 68K and S-100 80286 CPU board PCBs
ordered next but they are not cooperating.
The S-100 68K CPU board is nearly complete and
should be done soon. It has taken much longer
than I expected though. I would like it to
complete trace route optimization before
In the meantime, I am thinking we could make
another round of S-100 board reorders. What I
am thinking is the S-100 IDE V2 PCBs are
always popular and so are the S-100 buffered
prototyping board PCBs. I would like to do
another round of those and hopefully while
they are settling the S-100 68K CPU and the
S-100 80286 CPU boards will complete or at
least get “close enough”
Another idea is the S-100
bus terminator board. Basically there are 10
builders willing to get these boards “as is”
which is the full sized PCB with some
prototyping area. Nothing fancy but useful
for terminating a legacy S-100 backplane.
However these have *NOT* been
prototyped so there is some additional risk.
I think it is minor though since the S-100
backplane has this exact circuit and it works
Comments? Questions? All welcome! Please
lets discuss what the next steps should be.
Thanks and have a nice day!
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