This document contains definitions for:

1x is the 894 KHz CPU Clock rate equal to the native rate of the CoCo 2.

2x is the 1.788 MHz CPU Clock rate equal to the native rate of the CoCo 3.

3x is the 2.682 MHz CPU Clock rate equal to the clock rate of a GINEx equipped  CoCo 3.

4x is the 3.576 MHz CPU Clock rate equal to the clock rate of Sock Masters double speed  CoCo 3.

8x is the 7.152 CPU Clock rate equal to the maximum rate of the Matchbox CoCo.


CoCo 3
The Tandy Color Computer 3 was sold by Radio Shack between 1986 and 1991.
Backwards compatability with this computer is a Major goal for both CoCo 4 and CoCo 5 projects.

CoCo 4

  Many attempts have been made to create a "CoCo4" but from my point of view at a minimum a CoCo 4 must
  include:

CoCo 4 Plus

Additional new features such as support for:

CoCo 4 Plus Plus

Additional new features beyond the CoCo 4+ such as support for:

MMU

An MMU is a Memory Management Unit the MMU in a computer allows a CPU to use more memory than it's natural address space.
For example in the case of a CoCo3's the 6X09 CPU has a natural address space of 64K but the GIME - MMU unit allows it to address
up to 2 MB or RAM. In the case of the CoCo5 each of four virtual CPU's can address 2 MB of RAM in Standard Mode, one of these 
virtual CPU's ( CPU#0) can address up to 8 MB of RAM in eXecutive Mode another of these virtual CPU's ( CPU#1) can address up to
4 MB of RAM in Hardware allocation Mode and Four other CPU's #4 --> #7 may have there base address set anywhere above the low
8 MB of the 32MB of RAM GIMMEx32 accessible RAM but will get no direct MMU services beyond this direct address translation from
the GIMMEx32 these CPU's

MMU-A
MMU-A is the standard memory management scheme that the Tandy Color Computer 3 used.
It works by selecting eight , eight killobyte blocks ( pages ) , which are mapped into the 8 ( page frames ) accessible by a 6X09 processor.
This setup allows each CPU to use up to 2 MB of memory.
One Difference in the CoCo 5 implementation of MMUA is that the numbering of the memory pages is relative to each CPU and  the actual addresses come from not necessarily overlapping parts of the GIMMEx32's 32MB address space.
Click here for a detailed example.
MMU-X
Is the memory management scheme that CPU #0 uses to allow it access to up to 8 MB of the GIMMEx32's 32MB address space. It is one of two MMU modes that CPU#0 can access the other being MMU-A.
Click here for a detailed example.
MMU-H
MMU-H is the memory management scheme that CPU #1 uses to allow it access to up to 4MB of of the GIMMEx32's 32MB address space.
Click here for a detailed example.

CoCo RED Is a virtual color computer 3 ++ runing on virtual CPU #3 that may be assigned anywhere from 128KB to 2MB of RAM and be clocked from 1x to 8x.


CoCo GREEN Is a virtual color computer 2 ++ runing on virtual CPU #2 that may be assigned anywhere from 64KB to 2MB of RAM and be clocked from 1x to 8x.

CoCo Blue Is a virtual color computer 3 ++ runing on virtual CPU #1 it is only available when the system is in Tri-CoCo Mode and has 512K of RAM and be clocked from 1x to 8x.

Virtual CPU The CoCo 5 FPGA emulates a system where Four 6309 CPU's share resources primarily through a system of hardware and memory management coordinated by a custom 32 Bit GPU chip the GIMMEx32.

GIMMEx32
       Screen Layers

    TL TOP Layer covers up all other layers may be assigned a transparency to allow all of another layer to partial show through and may
          also have an assigned transparent color which allows the layers below that "color" it to completely show through.
    ML MID Layer covers up the two layers below it may be assigned a transparency to allow all of another layer to partialy show through
    and may also have an assigned transparent color which allows it to completely show through.
    BL BASE Layer covers up the layer below it may be assigned a transparency to allow all of another layer to partialy show through.
    and may also have an assigned transparent color which allows the layer below that "color" it to completely show through.
    BG SYSTEM BACKGROUND LAYER is a 10 bit layer using one of three color sets Red, Green or Virtual or a 7 bit Grayscale set.

     Sprite Layers

    There are Seven Sprite Layers there location with respect  to the Screen Layers is illustrated in the following diagram.

GIMMEx32  Color Sets

    Red Set      10 bit Color set four bits red three bits green and three bits blue RRRRGGGBBB for Background Screen Only.
    Green Set   10 bit Color set three bits four bits green and three bits blue RRRGGGGBBB for Background Screen Only.
    Virtual Set  10 bit Color set colors produced via a more complex method to mimic grandfathered color sets.
    Grayscale     5 bit gray scale set actually a subset of the Virtual Set.