V6Z80P

Click here for the v6z80p project website

The V6Z80P is a standalone computer PCB I designed based on a Spartan II 150K FPGA with a Z80 CPU running at 16MHz. By default the FPGA is configured with my own system architecture but it can 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 MMC/SD card connector.

The default architecture (called OSCA – Old Skool Computer Architecture) offers 256 colour bitmap / tilemap video modes, allows 55 hardware sprites per scanline, hardware scroll and line draw, a simple blitter and 4 channels of 8-bit sampled audio. OSCA outputs RGB TV and 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 Debug, allowing files to be run, memory to be examined, files to be downloaded etc. FLOS loads up on boot from an SD card (or from the 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.

Sooo… It’s essentially an 8-bit retro computer (but faster and with much better graphics:) which harkens back to “proper” machine code programming 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 (though only a couple of free IO pins). Incidentally, the “Webpack” software used to design the architecture is provide by 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 – which is constantly being updated – can be found here. (There’s also an email-based discussion / support group for owners).

Misc PCB info:

• 1 x MMC/SD card slot (OS supports standard 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 RS232 Serial Comms Port (PC compatible null modem cable supplied)
• 1 x RGB video out port (VGA signals, SCART TV cable supplied if required)
• 1 x 3.5″ Stereo out socket
• 1 x 2.1mm DC power jack socket (7.5v or 9volt mains adapter required around @ 1Amp)
• PCB dimensions: 116mm x 123mm.

The V6Z80P is supplied assembled and set up with OSCA as the default architecture (plus a Spectrum 48/128 emulator as an alternative config). It is supplied with a null-modem serial comms cable and RGB SCART TV cable (if required).

Availability: 05-09-2010:  The original V6Z80P has been superceded by the V6Z80P+, which is essentially the same thing with a few small changes (the video port is now a standard DB15 VGA socket, a few components have been changed etc). I currently have one V6Z80P+ board left for sale – drop me a line at the address below if interested. (It’s possible I may make more in future if there’s interest and the parts are still available)

Price: £85 GBP (plus postage + 3.9% paypal fee) – I can send the boards worldwide and will use whichever Royal Mail service you require. Please note: the price reflects the actual cost of the parts – this is only a hobby for me and I dont actually make much (if any) profit.