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  • I’ve made a ZX Spectrum Interface Card.. As you do.

    Posted on October 18th, 2014 Phil


    A while ago I made a home-brew diagnostic ROM cartridge to help me test faulty Spectrums – it was a very simple circuit based on a FlashROM and a discrete logic chip. Of course, the project slowly morphed into something bigger and I ended up creating my own multi-function Spectrum interface card!

    The SMART Card as it’s called (decode the acronym any way you want:) is now based on a CPLD and has 256KB of flash memory, 128KB of RAM, an SD card connector,  Kempston joystick interface, reset and NMI buttons. It’s really aimed at retro gamers who just want a simple, low cost way to load and play snapshot game files from a menu, right from power on (but it has some more advanced features too).

    I’m currently just gauging interest really but have the parts to build a few of these boards for sale.  There’s more info on the SMART Card here.


  • Trying out the PIC16F1829

    Posted on July 27th, 2014 Phil

    I recently bought some PICs for a project – the devices in question being the fairly recent 16F1829 variety.  (Reasons: Cheap, 32MHz, 20 pins, can self-program, 8K code RAM, 1K data, 2 x SPI ports – all good stuff). Having used the 16f627 for quite some time, a few things were immediately noticeable:

    1. These things are packed with peripherals and the datasheet goes on forever!

    2. A new-ish version of MPLAB is required. At first I downloaded MPLAB X – Oh man.. What a bloated,  over-complicated, C-orientated mess.  Sorry Microchip, it’s awful! Fortunately older versions of MPLAB are still available and v8.92 did the trick. The trick being, you know, ” Enter some code, click build, burn to chip”.  Simples.

    3. My venerable DIY Tait Classic parallel port programmer wont do. WinPIC800 supports the 16F1829 but only with their proprietary hardware so I ended up buying a clone of the PICkit3 which included a ZIF adapter for standalone programming. Check Ebay etc.

    4. There wasn’t a massive amount of example code on the net, so the first thing I did was make my own template. It’s here if you want to use it.

    Anyway, the chip appears to do what I need so hopefully development can now begin..

  • Shop facelift

    Posted on June 9th, 2014 Phil

    Thanks to me ol’ buddy and web design guru  Dick Dolby, my little retro components shop now has a proper ecommerce front end. Soooo.. if you need parts for Spectrum / Commodore – please take a look. I also offer keyboard repairs and composite video mod service for the Spectrum, and recapping service for both Speccy and Commodore 64.

  • Pendulum PCB – Professional Edition

    Posted on June 5th, 2014 Phil

    pendulum_pcbWell I ended up needing 40+ Pendulum PCBs. This would have been too much work to make at home even as single-sided board so I had a browse around for a low-cost production house to have them professionally made.  Didn’t take long to find PCB.HQEW.NET, who are cheap and efficient – it only took a week or so for the boards to arrive from China once dispatched. Highly recommended!

  • “Pendulum”daughterboard for the V6Z80P

    Posted on May 15th, 2014 Phil


    Following an enquiry from Spectrum emulation whizz Alessandro Dorigatti, I’ve made a small daughterboard for the V6Z80P that provides 28.000MHz and 28.375MHz clock signals – IE: perfect for the Spectrum and Spectrum 128.

    Although we’ve had very respectable Speccy emulation before now, further development was becoming tricky since the internal FPGA clocking was a based on a kludge to obtain higher clocking from the 14MHz and 16MHz oscillators available by default on the V6 (these values were below the magic 25MHz at which the Spartan II’s internal multiplier/divider PLLs can be used.) One immediate result is that the Spectrum 128 emulator now shows pixels of the correct aspect ratio, but hopefully it’ll open up future development too (I’m glad I added those unused GCLK pin headers now:)

    The board is at present a home-etched affair, but there are plans afoot to get it made professionally to better match the V6Z80P. It’s a very simple circuit based on biased 74HC04 gates – It just took a bit of experimentation to get them oscillating correctly (at the high end of the 74HC logic @ 3.3v, not all brands of logic IC are equal, it would seem.)