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S-100 Z80 CPU board

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    S-100 Z80 CPU board

    Hi! Just a quick peek at the next S-100 board in work. It's early on this project and it is coming along nicely. This will be next as the S-100 SRAM board is basically done awaiting it to complete finishing in the trace route optimizer and sending off to manufacturing PCBs. The S-100 Front Panel Bus Monitor prototype PCBs have arrived and it is in build and test phase. In the mean time I am working on the S-100 CPU board pictured here.

    Thanks and have a nice day!

    Andrew Lynch

    #2
    Oooh a Z80 CPU board.....
    Is your CPU board designed as a replacement board for an existing broken S-100 system or can a new system be built from scratch with the boards you have developed so far? What software would be needed?

    Nik

    Comment


      #3
      Hi Nik! Thanks!

      Actually, both would work. You could use the Z80 board to repair a broken S-100 system. You could also use it when the console IO board is ready to build a complete system from scratch. At least notionally, a system from scratch would be an S-100 backplane (you supply the power supply) with an S-100 Z80 CPU board, S-100 SRAM board, and the S-100 console IO board. That would give you primitive monitor ability.

      Optionally you could add the S-100 IDE board and you have a complete system for CP/M. Add in the S-100 Front Panel Bus Monitor and/or S-100 ASCII keyboard as you want or build your own peripherals with the S-100 prototype boards. You could also add your own legacy boards into the mix and future boards we are working on.

      We do not have an ETA for when this will be complete but we're on the way. However, getting to a system that is a complete "core" of the backplane, CPU, SRAM, and console IO board will be a major milestone in the project. That will allow us to pull the various parts together into an integrated whole versus the piece parts we have now.

      Thanks and have a nice day!

      Andrew Lynch

      Comment


        #4
        Just to add on Andrew's comments. We have finished the design. It's in essence the Intersystems z80-II S-100 board modified to have two 16K windows that can allow you the adderss up to 1MG of RAM. This is useful for working with 16 bit systems and CPM80+. It also has 0-8 wait states with seperate switches for M1, MEM-RD, On board 2732EPROM and I/O. Dont know the max speed yet, hoping for 8-10Mz range!

        For information about the Intersystems board see here:-
        http://s100computers.com/Hardware%20...s%20Z80-II.htm
        and here
        http://s100computers.com/My%20System...-Z80%20CPU.htm

        However before we run a "production board" that others may want to use, we will test the circuit out with a prototype as we have done before.

        Comment


          #5
          I was curious about whether you have the board designed with the option to configure the bus option onboard, for the 8bit S-100 or the 16bit ieee-696 bus or is it only for the 16bit ieee-696 bus ?

          =Dan Roganti
          Dan Roganti
          my corner of cyberspace http://www.rogtronics.net/blog
          Vintage Computer Federation http://www.vcfed.org/

          Comment


            #6
            Originally posted by Ragooman View Post
            I was curious about whether you have the board designed with the option to configure the bus option onboard, for the 8bit S-100 or the 16bit ieee-696 bus or is it only for the 16bit ieee-696 bus ?

            =Dan Roganti
            Maybe a dumb question, but why would you want a Z80 and a 2732 to use a 16-bit bus?

            Comment


              #7
              Originally posted by Ragooman View Post
              I was curious about whether you have the board designed with the option to configure the bus option onboard, for the 8bit S-100 or the 16bit ieee-696 bus or is it only for the 16bit ieee-696 bus ?

              =Dan Roganti
              Hi Dan! The S-100 Z80 CPU board is IEEE-696 compliant but uses the 8 bit modes.

              Thanks and have a nice day!

              Andrew Lynch

              Comment


                #8
                OK, I see, I was just wondering since the Z80 has only 64KB range, I gather that you must be adding the extra hardware to access all the extra memory pages for 1MB from what John was talking about regarding the 16K windows.

                But what is "CP/M-80+" , I can't seem to find a reference for this, is that just another name for CP/M-3 or something you're creating to support this CPU card ?

                I was wondering why sticking with the Z80 if you're releasing an ieee-696 card instead of the 8086 and then continue using CP/M-86. I guess since you have alot of Z80 code from the current N8VEM project that you can port over would be nice.

                On a side note, What about the solid-state floppy drives that you have on the NV8EM, would that be getting ported over to a S-100 card too, or is that already embedded in the S-100 IDE card that I ordered ?

                =Dan Roganti
                Dan Roganti
                my corner of cyberspace http://www.rogtronics.net/blog
                Vintage Computer Federation http://www.vcfed.org/

                Comment


                  #9
                  Originally posted by Ragooman View Post
                  But what is "CP/M-80+" , I can't seem to find a reference for this, is that just another name for CP/M-3 or something you're creating to support this CPU card ?
                  Hi Dan! I presume this means CP/M 3.0 since that is John's preferred OS although CP/M 2.2 or any 8080/Z80 type OS should run on it with some software work.



                  I was wondering why sticking with the Z80 if you're releasing an ieee-696 card instead of the 8086 and then continue using CP/M-86. I guess since you have alot of Z80 code from the current N8VEM project that you can port over would be nice.
                  This is more of an AND rather than an OR answer. Really there is little connection between the N8VEM ECB Eurocard system and the S-100 boards under development. In theory the software could be easily transferred if needed since the N8VEM source code is all available. One important purpose of the Z80 board is to form the "core" of an entirely free/open source S-100 hobbyist system. Using the backplane, with builder supplied power supply, a Z80 CPU board, SRAM board, and console IO board you get a minimally functional system (ie, a Z80 debug monitor program). Add the other boards like SMB, IDE, etc and you get increased functionality. Later on add in the 16 bit CPUs and the options grow further.

                  In any case I think we still need a starting point so hobbyists do not have to rely exclusively on legacy hardware. I believe it is essential to form the "core" system and work outwards from a common starting point. That doesn't mean you can't use these parts to repair/restore a legacy system because you certainly could. However if you are starting from scratch being able to just build the "core" from available parts is an enormous advantage. I think this is useful to both new hobbyists with little or no S-100 hardware as well as more experienced hobbyists. The new hobbyists can get started using the system using affordable available common parts and add legacy components later. The experienced hobbyist can set up their system on the side as a test system to help repair/restore other legacy hardware. Both benefit from the common reference.

                  Don't be misled by the IEEE-696 compliance. It is just a design standard that helps the system evolve in a consistent manner but not forcing us to go pure 8 bit or 16 bit or restricting the architecture in some fashion. At some future point when the system is more complete, the hobbyist will have the option to build their system up using a Z80 CPU board for CP/M-80 or an 8086 CPU board for CP/M-86. We just have to get past these many issues associated with S-100/IEEE-696 board design.

                  Seeing the final products really are not a good indication of how complex a project this has become. John does the initial design with the schematic and I mostly build the PCB but we work together closely on converting the design in to a real board. The schematic affects the PCB layout and vice versa so there is a lot of going back and forth before the final product comes out. It is quite complex and we've uncovered many issues. IEEE-696 adds more complexity but we've also had issues in getting the EDA tools to cooperate plus the manufacturing, etc. A lot of things which independently are simple become much more complex when all joined together into a process and start affecting each other. The effect is each board now basically requires an internal prototype PCB or two just to get all the details set properly.


                  On a side note, What about the solid-state floppy drives that you have on the NV8EM, would that be getting ported over to a S-100 card too, or is that already embedded in the S-100 IDE card that I ordered ?

                  =Dan Roganti
                  Those are really just a matter of software in the CP/M CBIOS. Adding similar functionality to our system could be done by porting that code to the new Z80 board and using the S-100 SRAM board for the "RAM drive" and the EPROM board for the "ROM drive". The Z80 CPU board will not support the RAM/ROM drives by itself though as it has only minimal boot ROM (2732 EPROM) and no on board RAM.

                  At the moment, the board design, PCB layout, and prototyping are higher priority than PCB manufacturing. What time I have available is spent getting the boards laid out and prototype PCBs made so John can get his ideas off the paper and on to real boards for build and test debug cycle. Once we get past the "core" boards, I am hoping to spend more time and effort getting the PCBs manufactured but right now there is not enough time to do both. There are several PCBs basically just waiting for manufacturing either as is or with minor changes (backplane, regular prototyping, buffered prototyping, IDE, ASCII keyboard). There are some more that are nearly ready like SRAM is just waiting for trace optimization to complete with others in prototype phase (SMB). The Z80 CPU board is nearing prototype board build and test phase. The designs partially exist for EPROM and PIC but aren't ready for prototype boards yet. However there are many still on the "drawing board" waiting their turn with the most important (IMO) being the console IO board as it is the last piece needed for the core system.

                  Thanks and have a nice day!

                  Andrew Lynch
                  Last edited by NobodyIsHere; April 15, 2010, 03:43 AM.

                  Comment


                    #10
                    Hi! John posted a web page on the S-100 Z80 CPU project here:

                    http://s100computers.com/My%20System...PU%20Board.htm

                    Thanks and have a nice day!

                    Andrew Lynch

                    Comment


                      #11
                      Just to add what Andrew has above. I have started to write up a description of the Z80 board. Here is an early version:-
                      http://s100computers.com/My%20System...PU%20Board.htm

                      Comment


                        #12
                        Originally posted by monahan_z View Post
                        Just to add what Andrew has above. I have started to write up a description of the Z80 board. Here is an early version:-
                        http://s100computers.com/My%20System...PU%20Board.htm
                        Have you got a ballpark figure what this'll cost by the time it's all assembled?

                        Comment


                          #13
                          Hi! The cost of the final assembly is up to the builder. Typically the PCBs cost $20 plus $3 shipping in the US and $6 elsewhere. Total costs of assembly vary depending on what parts you use, where you get them, reuse salvage, scrap, or buy new parts, etc. Given the board is entirely common 74LSxxx ICs, discrete components, a Z80, and EPROM, I suspect less than $100 although most builders should be able to build it for much less.

                          Thanks and have a nice day!

                          Andrew Lynch

                          Comment

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