The Original SGM 1983

[Captain Cozmos]

I looked around but I have not found an answer so maybe one of you can answer this.

 

I get the idea of the new SGM and how it works.  Added memory and a sound chip.

However, you plug a cartridge in the top of the Colecovision that uses that extra mapped memory.

 

OK, makes sense.

With the original SGM you insert a wafer tape and hit reset.

How did that take over the system and boot from the tape?
 

Did the SGM have its own BIOS?
If this is the case was it just like the Atari Adapter that only used the CPU clock, power supply and the TV circuitry for the out.

 

I would think that it still uses the CPU.

Maybe shadow the BIOS with updates to it's built in ram like the Full version of the ADAM?

I want to look to the ADAM expansion module for the answers but I am not too keen on how that takes over the system.
As I understand it uses a series of chips as a buffer or some deal like that.

But what has priority in the boot process.  The Colecovision BIOS or whatever rom is connected to the expansion port.

Edited April 12, 2022 by CaptainCozmos20863

[TPR]

I'm going to assume the original design was probably not too far off on how the ADAM handles loading games from a DDP.  If you had the SGM connected, inserted a wafer tape, pressed the reset button, the load would happen off the wafer tape very similar to how the ADAM loads a game from the DDP.  That's at least my "educated guess." 

[Pixelboy]

Yeah, any expansion module plugged into the front expansion port of the ColecoVision has the ability to "take over" the machine and do whatever it wants, to the point where the native BIOS and whatever cartridge is inserted into the cartridge port are ignored. That's how the Expansion Module #1 works, it just suspends everything that normally happens at boot on the ColecoVision and takes over. The "original" Super Game Module would have worked in the same way.