Amstrad on an FPGA

If you are from the United States and of a certain age, it is very likely you owned some form of Commodore computer. Outside the US, that same demographic was likely to own an Amstrad. The Z80-based computers were well known for game playing. [Freemac] implemented a working Amstrad CPC6128 using a Xilinx FPGA on a NEXYS2 demo board.

The wiki posting is a bit long, but it covers how to duplicate the feat, and also gives technical details about the design. It also outlines the development process used ranging from starting with a simple Z80 emulation and moving on to more sophisticated attempts. You can see a video of the device below.

Computers of that era often made compromises to save money and work around limited horsepower. For example, the Sinclair computer famously blinked its video when you were typing because the CPU couldn’t drive the display and read the keyboard at the same time. The Amstrad restricted CPU access to memory to avoid conflict with the video hardware, so the 4 MHz CPU was effectively throttled to just over 3 MHz. Exploring these old architectures can show you a different way of thinking compared to the modern web browser eating up dozens or hundreds of megabytes of memory.

We’ve seen Amstrad clones before. We’ve also seen the unholy union of a real Amstrad and an iPod Shuffle where the iPod stood in for a data cassette. Wonder if the FPGA simulator can read tapes?

21 thoughts on “Amstrad on an FPGA

  1. I still have a complete Amstrad CPC 6128 That I used in the early 80’s. I really loved it, and used it until I moved to the USA. I used it a bit in the US, but moved to PC as I could not find 3inch floppy disc for it. This was so much better that the 3 1/2 inch floppies that took over the world. Kudos for making it in an FPGA. What do you use for mass storage?

    1. These days there’s a bunch of new peripheral hardware that works great.

      1. There’s a wifi/romboard that also provides sd card storage. Compatibility can be a bit hit and miss, although it’s under active development.
      2. there’s the HxC disk emulator that lets you read disk images off an sd card or a usb stick,
      3. or If you want to go super cheap you can get a Gotek disk emulator from ebay for peanuts (which has a fairly crappy firmware) and pay a little extra to reflash it with a copy of the HxC firmware and get all the benefits of that.

      1. It can be done. Just takes practice. I’ve been doing my monitors by hand for quite some time. Plus the added bonus of extra head room behind the monitor. No pun intended.

  2. Amstrad was late to the home computer market, most people in Britain had either a ZX Spectrum or Commodore 64. A few had a BBC Micro or its little brother the Electron because their parents wanted them to have a computer compatible with the one in school rather than a computer for playing games.

    Hardly anyone had an Amstrad CPC as the Atari ST and Amiga were beginning to appear by the time Amstrad got their act together. Just about the only people who Amstrad owners could say their computer was more popular than were Tandy CoCo owners as unlike the US the CoCo never caught on in the UK.

  3. According to Wikipedia, they sold about 3,000,000 and apparently a deal with Schinder meant they were popular in German-speaking Europe, as well as France, Spain, and they do mention the UK.

  4. Also…. the Sinclair machine which was around & popular at the time the Amstrad CPC was released weren’t the much earlier & extremely basic ZX80 & ZX81s, it was the ZX Spectrum which was much more capable than either of those machines.

    I always thought that while the CPC had a nice palette & games written to take advantage of its modes did look good (Head Over Heels, Operation Wolf) they also didn’t have the custom hardware to move things around so it often suffered in direct comparison with both the Spectrum & C64 when it came to smoothness. Not always, but often.

    1. >direct comparison with both the Spectrum

      ?, as RW wrote Amstrad was basically a Spectrum done properly, it did _everything_ better. Proper sound with buildin AY, proper graphics with 16 and 4 color modes with no attribute clash, proper color palette for that matter (better than c64), proper storage with buildin tape/floppy, proper monitor instead of stealing parents TV, proper keyboard instead of dead fish.
      It did all of that at 2x Spectrum price. Impressive, yet it was still a spectrum inspired design with anemic CPU and no hardware sprites – some games looked better than C64 versions, but everything ran god shit slow.

      Of course people liked it because bare C64 was ~5x Spectrum/~2x Amstrad price.

      Here is a funny YT with direct comparison, personally I find Spectrum people delusional :)

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