[Coco] DECB DOS Command

[jdaggett at gate.net]

Gene 

>From what I have been able to determine there are three OS9 modules that are 
stored in track 34. REL, BOOT and OS9p1. 

DECB loads track 34 into ram and executes. IF it sucsessfully loads in the right 
4608 bytes then the OS9 boot process can begin. Otherwise it fails and ends in an 
endless loop. REL is the relocator code that eventially calls OS9p1. BOOT is called 
from OS9p1 and contains the init table and loads the rest of the files needed into 
ram. OS9p1 passes control over to OS9p2 and then to CLock and then to CC3go.  
Then OS9 is ready to rock and roll. 

The module BOOT is system specific. It can be tailored to for floppy, IDE or SCSI 
drives. Probalby even a multimeadia card or flash. 

I am wondering if all the necessary code be loaded into a rom, have the Rom COde 
create a ram drive and move all necessary code into the ramdrive and then 
deactivate the internal rom. Then OS9 boots from a ram drive as default. 

I was looking at some of the OS9 source code and it seems as if the boot process is 
somewhat flexible and tailorable.


james

On 13 Dec 2003 at 6:27, Gene Heskett wrote:

> On Saturday 13 December 2003 03:09, tim lindner wrote:
> >I was just reading the Disk BASIC unravelled book and came away with
> > the following question:
> >
> >Why does the 'DOS' command first issue a SWI3 instruction?
> >
> >Disk BASIC sets up the SWI3 vector to do nothing. It just returns to
> > the caller.
> >
> >Also there is a bug noted in the DOS command: It will read track 34
> > from the last drive used. It is documented to only read track 34
> > from drive zero. But drive zero is just what DECB defaults to.
> >
> Yes, thats true.  But, when track 34 is loaded and exec'd, that code
> will then access the drive its been hard coded for, usually /d0.  So
> the only thing you would need on that disk is a valid track 34.
> 
> -- 
> Cheers, Gene
> AMD K6-III at 500mhz 320M
> Athlon1600XP at 1400mhz  512M
> 99.22% setiathome rank, not too shabby for a WV hillbilly
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> by Gene Heskett are:
> Copyright 2003 by Maurice Eugene Heskett, all rights reserved.
> 
> 
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