V6Z80P

The V6Z80P+ is an original standalone computer I designed based on a Spartan II XC2S150 FPGA and physical Z80 CPU. By default the FPGA is configured with my own system architecture but it can be reprogrammed to do anything you want (within reason:) The V6Z80P+ has 3 memory buses, one for the CPU and main memory (512KB), plus another 512KB and 128KB. There are two Atari 2600 / Amiga-like joystick ports, PC mouse and keyboard connectors, an RS232 serial comms port, a stereo audio socket, a 12bit colour video-out socket and SD card connector.  The latest revision of the PCB (v1.1) has two master oscillators,  16MHz and 14MHz, the latter is used for cycle-perfect ZX Spectrum 48  emulation - IE: 3.5MHz when subdivided by the FPGA.  (Kudos to Alessandro Dorigatti for the Spectrum emulator config!). There is also a pin header allowing other oscillators to be connected if desired.

My own custom architecture  is called OSCA (for Old Skool Computer Architecture) and offers 256 colour bitmap / tilemap video modes, 55 hardware sprites per scanline, hardware scroll,  line draw, a simple blitter and 4 channels of 8-bit sampled audio (Amiga style).  OSCA can output RGB TV or VGA signals.  TV mode offers interlaced and non-interlaced modes (both PAL 50Hz and NTSC 60Hz) / VGA mode video is standard 60Hz or non-standard 50Hz. Full screen resolution (non-interlaced) in 256 colours is 368*256 (PAL) Click Here for Youtube videos of demos made with the board configured with OSCA.

I also made a simple OS, called FLOS (Freezer Like Operating System) – this behaves a bit like a cross between DOS and a Debug/Freezer cartridge from the home computer days – it allows files to be loaded and saved,  programs to be run, memory to be examined etc. FLOS loads up on boot from an SD card (or from the onboard EEPROM), but its not fixed – you could create your own OS if you wanted, or just have the V6Z80P+ boot straight into some arbitary Z80 app.  In addition there’s simple apps and utils for FLOS (such as a file manager, text editor, native assembler etc) and tools for the PC such as a serial file transfer program / graphics converters etc.

Sooo… The V6Z80P is essentially a modern standalone 8-bit computer system which harkens back to the days of “proper” programming (y’know, when you could hit the metal and not worry about APIs and abstraction layers and all that nonsense:)  Or.. you could use it as an FPGA trainer PCB which just happens to have a physical Z80 CPU onboard (but only a couple of free IO pins).  The “Webpack 10.1″ software used to design the architecture is available from Xilinx for free,  and allows designs to be entered via schematics or high level descriptive languages like Verilog or VHDL. You can upload these new configs via the JTAG pins or burn them to the onboard EEPROM (which can store multiple architectures). An online version of the V6Z80P+ documentation and links to the entire project archive can be found here. (There’s also an email-based discussion / support group for owners).

Misc PCB info:

• 1 x MMC/SD/SDHC card slot (OS supports FAT16 file system)
• 2 x Joystick ports (Atari-standard, the original Megadrive pads are compatible too)
• 1 x PS/2 Keyboard Port (PC standard)
• 1 x PS/2 Mouse Port (PC standard)
• 1 x Serial Comms Port (4 pin mini-DIN:  RX,TX,GND) - A PC compatible null modem adapter cable is supplied.
• 1 x RGB VGA video port (SCART RGB TV adapter cable supplied for TV-out)
• 1 x 3.5″ Stereo out socket
• 1 x 2.1mm DC power jack socket (7.5 or 9 volt mains adapter capable of supplying around 1 Amp is required)
• PCB dimensions: 116mm x 123mm.

The V6Z80P+ is supplied assembled and set up with OSCA and FLOS installed (plus Alessandro’s cycle-exact Spectrum 48 emulator and my own non-exact Spectrum 128 emulator as alternative configs). It comes with a null-modem style serial comms cable and RGB SCART TV cable. 

Availability:  [15th Dec 2011] The last of the current batch has been sold and I’m not sure if/when I’ll make any more.  Still, you can Email me at the address below if interested - I may be pursuaded (as long as the parts are still available / affordable).  Price for a complete board is £88 GBP (plus postage + 3.9% Paypal fee) – I can send worldwide.  Please bear in mind, I only make these as  a hobby - the price reflects the actual cost of the components, I hand solder everything and I don’t actually make much (if any) profit.