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 the ready.
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 J
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 wrote:
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 as well.
On Sunday, February 24, 2013 11:17:26 AM UTC-6, lynchaj wrote:
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 ordering PCBs.
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 fine.
Ideas? Thoughts? Comments? Questions? All welcome! Please lets discuss what the next steps should be. Thanks and have a nice day!
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