The CoCo 4 case is almost identical to a Color Computer 3 case to the degree that one option is to reuse a standard Color Computer 3 case. The following set of slides will help to visualize various aspects of the CoCo 4 design.

Slide Show.

Standard version.
VGA Exits via the bottom where RGB would exit on a standard Color Computer 3
A 3-D printed mounting block is attached to the origional case with glue.
Serial Cable is taken inside the case to attach to a strain relief directly on the motherboard and exits via the former RF output port.

Version with Backside Coutout for High Speed DB-9 Serial Port.
This version involves modifying the case or getting a clone case top 3-D printed.

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If the ROM select set to 3 with no cartrige pluged in the CoCo 4 boots to Extended Color Basic 2.1
If the ROM select set to 4 the CoCo 4 boots to either:

00 - Basic 4, 01 - Basic4 Drive Wire Auto Boot 10 - Start Menu 11 - Custom ROM (Which user must supply) If The Start Menu Option is not selected them hold down S on power up. Holding B or D on power up starts Basic or Drive Wire Boot respectively.

There should be at least 1 Meg of memory.
Preferably built in.
There also should be at least 8K of battery backed static memory to store settings and keyboard macros.

Compareing the CoCo4+ with the CoCo 4 we see that the memory has been upgraded to 4Meg.
This requires an alternative MMU mode where there are 4 8K banks for the low 32K and 2 16K banks for the high 32K.
The alternate mode would require special software so is only used with special software that is triggered by an interupt.

The main difference between the CoCo4+ and the CoCo4++ is that there is an aditional virtual 6309 and an additional 512K RAM.
The origional CPU we call CPU#1 and the additional CPU we call CPU#2.
CPU#2 uses standard MMU mode only so there is access a maximum of 2Meg.
The aditional three 512K blocks available to CPU#2 are assigned at POWER ON STARTUP.

CPU#2 has exclusive access to the additional 512K "Superblock G".
It also has shared access to 3 Other Superblocks by default these are:
"512K-Superblock F" to allow for 1M RAM if not used by CPU#1
"256K-Superblock M" for Shared Buffer Access.
"256K-Superblock T" for virtual casettes.
and the Top 512K of "Superblock U" for 2 160K volatile drives and the shared 160K "Drive 8".

CPU#1 has access to the non-volatile 160K drive U0: and a virtual 720K OS9 /ud1.

This switch determines if the computer will boot in CoCo3 or CoCo4 mode
on the next power up or equivalent.

Just the same as Composite out on a Coco 3.

For a VGA or SVGA monitor up to 1280x800.
(1280x720 maximum displayed resolution)

3.5 mm Sterio Out Jack
Attanced to the "Mixer." component.

USB 1.1 Port on underside attached comes out at the back and can be cliped here for strain relief.

Two supported functions:

1. Firmware update cable
2. USB Mouse

Just the same as Composite out on a Coco 3 except

• Handeled by CPU #0
• Soft Resets only the CoCo in Focus.
• Special functions defined by CPU #0

Two Stacked Standard Coco Cartridge Ports
are located on the Right Side.

The Stacked Coco Cartridge Slots and an
Internal Coco Cartridge Slot can be assigned to specific CPU's
or assigned to a "Virtual Multipack" which can then be assigned to a CPU.

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