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From: lnewman@emdeng.Dayton.NCR.COM (Lee.A.Newman)
Newsgroups: comp.os.os9,comp.sys.m6809
Subject: Re: Adapting coco OS9 to other systems
Keywords: OS9, coco III, uniboard
Message-ID: <651@emdeng.Dayton.NCR.COM>
Date: 28 Mar 89 17:41:16 GMT
References: <386@aucis.UUCP>
Reply-To: lnewman@emdeng.Dayton.NCR.COM (Lee.A.Newman)
Organization: E&M Dayton, NCR Corporation, Dayton, Ohio
Lines: 36

In article <386@aucis.UUCP> easton@aucis.UUCP (Jeff Easton) writes:
>Okay, level 2 is out.  I could use it later after I build that 2 Meg
>bank switching RAM disk I'm thinking about :>
        If all you want the extra memory for is a ramdisk, yes, I agree
        with you that level 2 is out.  The advantage af level 2 is that
        you can have more than one process running in its own 64K process
        space.

Here's my guess at a scenario for porting it. [Coco OS9 to Jeff's system]
> 
>	1> Buy the OS9 level I & the assembler package

         OS9 level 1 comes with the assembler. (No extra charge!)
>	2> Rewrite the 6551 ACIA drivers for the deluxe RS232 pak
>	    for my 6551 at a different address.  sounds easy
         No need to rewrite, unless you don't like the driver.  With
         OS9, all you have to do is change the address in the descriptor.
>	3> Rewrite the disk drivers for my WD 1793 disk controller
>	    what chip does the coco use? a WD 17xx I think
         I'm not sure, but I do know it is a WD 179x. (1797 maybe???)
>	4> Write a boot strap loader for OS9
>	5> At this point I should be able to boot OS9 with a 
>	    terminal connected to my serial port.  I then
>	    can write the drivers for my video (MC6845 based) and
>	    keyboard (7 bit ASCII w/strobe).
          If you can find someone with the OS9 drivers for a Coco
          WORDPAK or WORDPAK II, this addon board for the coco uses
          a 6845.  I beleive it was manufactured by PBJ.
> 
>Does OS9 require a timer for switching processes?  I have a 6522 VIA
>with 2 8 bit timers.  Is this sufficent?

        The coco uses a 60 Hz timer interrupt.  It only has one timer.

Lee Newman
lnewman@emdeng.dayton.NCR.com