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A new modular homebrew computer is in the works!

Check out the SC-1!

drawing of sc-1

What is it?

        The SC-1 as its being tentatively named, is an attempt at a modular S-100 style minicomputer.
        Yes, I said that correctly, minicomputer, not microcomputer.

        A simple way to think of this project is, a big RC2014 kit.

        Minicomputer is a term for machines that fit somewhere between the old full-room mainframes
        of the 1950's and 60's and more into the server-rack sized devices of the 70's. The PDP series
        of machines starting with the PDP-8 are a great example something often considered a "minicomputer",
        as opposed to the "microcomputers" able to fit on a single desk like the commodore 64, or TRS-80.

        Bigger = cooler

What does that mean for me?
        The point of creating this is to have an easy to assemble, fun to build, hobbyist computer that
        can hopefully help teach the function of computers better than many of the "plug stuff in and solder it"
        type kits already avalible to be put together. But with the added bonus of having a cool full sized
        machine unlike the FPGA, Raspberry Pi, or other system-on-a-chip type reproductions out there.
        You can slap this inside a woodgrain box covered in dymo labels like its 1975, or you can fill a
        whole server rack to feel like you've snuck a Data General machine out of a museum when no one
        was looking, or perhaps somewhere inbetween.

What are its Specs?
        I'm aiming for a 4U rackable design using pre-existing rackmount solutions for the main case.
        Being that the machine is intended to be modular, the exact specs will vary from one system to
        another. The system will use an S-100 like backplane allowing users to add additional memory,
        peripherals, and even swap out CPU's if so desired.

What kind of Logic?
        Chips get old just like we do, so first and foremost the goal is to require as few "vintage" chips as
        possible. Partially to keep the cost down but mainly you dont have to hunt for that $700 first run
        Intel 8080. Whenever avalible, modern reproductions or equivalences will be chosen as default.
        With that being said the current plan is to have three options:
        Standard integrated circuts where applicable and sensible. this is basically just a Digital Group
        machine clone at this point but without all the fiddly wirewrap.
        Resister-Transistor Logic! Technically closer to Diode-Reistor-Transistor logic, but regardless,
        this is close to the intended use case to assemble the machine. It'll be slow, it'll be big, and it
        probably wont be the cheapest option, but it'll be cool, and thats what counts. Some things are
        just not practical as a purely transistorized package, like memory for instance. There will absolutely
        be "transistor memory cards" avalible if you like that kind of torture, but there will also be more
        modern integrated circut options to make use of as well. It will take awhile to figure out the 8080
        Z80 CPU's but a transistorized 6502 has already been worked out and will be avalible in "card"
        form for those who want to go all in.
        Relay logic. For when you really want to run up your electric bill and go deaf at the same time.
        This is really going to have to be a separate machine altogether and may get branched off as its
        own project as a result, but its definately in the plans. Again, like with transistors, some things just
        aren't practical for a diy project, and so it'll be a mixture of relay "cards" and transistor or integrated
        circutry for the stuff that would otherwise fill up your whole house let alone a single server rack. But,
        just as with the transistors, the option will be there to go 100%

What will it look like?
        It will have a very expansive front panel for complete programming and manipulation without
        the need of a terminal,a cassette interface for saving and loading programs, an rs232 port for
        when you get tired of flipping switches to load in your programs, fans to keep you and your machine
        cool (or warm, depending), and quite a few expandable peripherals and features (like probably
        an SD or CF interface for convenience).

Planned Options:
      -  CPU - Z80, 8080, 6502, custom non-integrated design
      -  Memory - 1, 4, 8, and 32k boards, probably more.
      -  Front Panel - less altair, more IBM 360 :)
      -  Data Input - Cassette interface, rs232, front panel, paper tape/punch card
      -  Video - RS232 terminal, VGA, possible RF or composite video out

Peripheral "card" modules:
     -   RS232 serial, a very simplistic serial card to use with your own supplied terminal.
     -   ESP32 (or simmilar) Wifi + Modem, to connect to your favorite BBS or home file server
     -   Magnetic Tape interface, for loading and saving programs via cassette or reel to reel (or mp3)
     -   Integrated Terminal, with more modern video out options and a keyboard interface.
      -  Floppy/HDD controller, for use with real drives, or with gotek solutions.
     -   SID sound chip, using FPGASID
     -   Custom sound chip.
     -   various other peripherals as ideas come to mind and iron goes to pcb.
      -  Paper Tape/Punch reader
      -  Punch card memory, ala FACOM 128
      -  DIY keyboard, to also be used with other kit computers or terminals as well.
        A "bog standard" machine will be a z80 cpu, 8kb of ROM, 32kb of RAM, and a serial card or
        front panel interface (It will be possible to use the machine with only one or with both).
        The front panel, although *strongly advised*, wont be required. There will also be plans to build
        a case for the machine from easy to aquire standard sized lumber if you dont want a rack at home.

What does it do?
        The current plan is to have the machine be capable of running CP/M and Basic, with the potential
        of additional options as time and development provides. The purpose of this is to allow the
        extensive amount of software and documentation already in existance for those (and others) to be
        run on the machine. Programming may be fun, but its a lot more fun when you can have a backlog
        of existing code to run on your cool new toy. I also like the idea of being able to make a "big Sinclair",
        or a "big Commodore" which should be totally possible with reproduction and compatable parts.

So is this an S-100 machine?
        No. It will use "cards" and a backplane like one, but it wont be compatable. I dont know yet how
        many pins it will use as of yet, that will be determined as the design progresses.

Can I build one?
        Of course! much of the project will be "open source" and I'll make sure to sell runs of boards for
        others to build themselves. I may even consider offering files to let you etch your own PCB's from
        copper plates.

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