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blitter-vhdl-6502

The "Blitter board" is a series of board for the Acorn 8-bit Microcomputers. These boards are used to replace the CPU in an Acorn 8-bit computer such as the BBC Micro, Electron or Master.

As well as replacing the CPU the boards provide a set of enhancements to the machine:

  • A blitter - a co-processor which can plot graphics to screen memory very quickly - roughly modelled on the Amiga's Blitter (Agnus)
  • A sound chip - an enhanced sound card which provides 4 or more 8 bit PCM channels - roughly modelled on the Amiga's Paula sound chip
  • A raster chaser - "Aeris" a co-processor which can update hardware registers at various points on the screen during screen scanning - analogous to but quite different to the Amiga's Copper
  • Memory expansion:
    • Full Sideways ROM/RAM in various configurations (Flash EEPROM, Fast RAM, Battery Backed RAM)
    • Page-Wide expansion
    • For 16/32 bit CPUs a linear address space
  • Soft or Hard CPUs with separate configurations
  • Alternative CPU's. The main CPU can be replaced with either an FPGA IPCore CPU (T65) or with a plug-in cpu

Further reading

Project Structure

doc						Documentation
src						Code
  hdl						VHDL/Verilog projects and libraries
    chipset					The Chipset (Blitter/Paula/Aeris/DMA etc) (used various revisions of board)
    library					Shared by many projects
      3rdparty					Code from other projects
      	I2C_minion				I2c peripheral from Peter Samarin
        HamsterWorks				Stuff from Mike Field for HDMI
        MikeStirling				Stuff from Mike Stirling/Hoglet from the BeebFPGA project
        Missing					Where to place missing 3rd party libraries with incompatible licences
          JohnKent				6800, 6809 cores
          P65816				65816 core	          
        T6502					The T65 core
        TG68					The TG68 core	        
      fishbone					The Fishbone Bus basic components and definitions	    
      simulation
    mk3 (or mk2)				Projects and files relevant to the Mk.3/2 board
      boards					contains individual builds
        cpu-04-min				MAX10 4000LE build with minimal options
      	cpu-16-max				MAX10 16000LE build with all options except HDMI
      	cpu-16-hdmi				MAX10 16000LE build with all options including HDMI
      shared					HDL shared between all mk.3 builds
      testing					Projects for board testing and production
        mk3-board-erc				A simple Project to perform board ERC  
        mk3-erc-68000				Perform ERC on a 68000 plug-in cpu board
      simulation				ModelSim testbenches and test assembler code
      	sim_asm					Assembler test code for various CPUs
      	sim_tb					VHDL testbenches and .qsf configurations
    shared					Blitter board specific files shared between mk2/3
    simulation_shared				TODO: move to library/simulation