Installation of recent CollapseOS releases ; HOW ?

[eprive]

Hello,

I built a Z80-MBC2 board a few years ago, and I'm now trying to make something that works with CollapseOS.
The operating system works, and I also see that the version that is in the archive is several years old. In s220718-r240620_sd_v1 see the creation date of cos.bin : June 23, 2020.
I would like to upgrade to a recent version, so I also checked the Collapse website : www.collapseos.org
There I find a whole series of newer releases, but no clear explanation how to install them. The description I see on Github, namely : https://github.com/hsoft/collapseos/blob/master/doc/hw/z80/z80mbc2.txt
no longer seems complete.

The designer (Virgil Dupras) has informed me that CollapseOS is "self-hosting". But that still doesn't clarify the mthod that cos.bin was generated. Can you give me some insight on how you handled that?

Concrete questions :

1. Which CollapseOS edition / revision is distributed for the Z80-MBC2 in the above archive file ?

2. Is there a source file with Z80 code used to create cos.bin ? Where do I find it?

3. Which compiler, and on what kind of development machine was used?

The Z80-MBC2 has unique hardware to perform character I/O to the terminal and access files on the SD card.
4) Have any adjustments been made specifically for the connection with IOS on the Z80-MBC2? If so, how?

5. The CollapseOS POSIX scripts create a file called : blk.fs
   That is as I understood the disk contents for CollapseOS. How was this converted to DS4N00.DSK ?