RetroSys2019 CPU Board

The first “real” board for the RetroSys2019 system is the Z80 CPU board. Compared to older/other designs it has some specifics :

  1. A DIL crystal oscillator. In the past I had quite some issues with crystals mixed with modern TTL creating unstable clock signals. A DIL crystal oscillator will fix this and when using a socket at the same time gives the opportunity to play with the clock speed without soldering.
  2. Fully buffered bus. Which not only buffers the CPU signals (increasing the fan-out) but also giving the opportunity to put the CPU board in “Tri-State” , making the bus available for another processor, e.g. an Arduino to write the memory.
  3. A decent (TL7705) reset signal generator.

The board as it appears in Kicad (Non-Rendered and Rendered versions) :

RetroSys2019 CPU Kicad Gerber
RetroSys2019 CPU Kicad
RetroSys2019 CPU Kicad 3D view front (Non-Rendered)
RetroSys2019 CPU Kicad 3D view back (Non-Rendered)
RetroSys2019 CPU Kicad 3D view front (Rendered)
RetroSys2019 CPU Kicad 3D view front (Rendered)

DISCLAIMER : Please note that these boards have only been designed VERY recently . They are currently being manufactured and I will post progress in my blog.

Comments

This post currently has one response

  • Nice projects. I’m in the UK and I built a lot of Elektor projects including the SC/MP computer which pre-dates the Junior – picture here (not mine).

    https://www.flickr.com/photos/eveliensnel/3115361201

    I also built an Elekterminal…

    https://www.worthpoint.com/worthopedia/elektor-44-december-1978-ascii-512087567

    The parts were hard to find and I was 15 at the time so I didn’t know much back then or have much money. Eventually I built an 8080 system then upgraded it to a Z80, all on strip board. I got a floppy drive and wrote a disk operating system similar to CP/M. Under pressure from my friend who only knew BASIC on a Commodore PET, I wrote a BASIC interpreter for it.

    Since then I’ve had a 35 year career designing electronics and software. Now I’m getting all nostalgic and ‘giving back’ to the community, particularly retro-computing. I recently designed a terminal – sort of an upgrade to the Elekterminal but much more capable (colour for a start). You can find the details here…

    http://debuginnovations.com/TTL_Terminal

    I like what you’re doing with the Z80 system. If I can help at all, I’d love to. All the best.

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