[Coco] VCC and HDBDOS

[Kip Koon]

Hi Robert,
Thank you for that explanation and thank you for all the contributions you have done for the CoCo Community!  I really appreciate it very much.  I now have an RGBDOS.ROM image file for my copy of VCC 2.00.  Thank you.  Take care my friend.

Kip Koon
computerdoc at sc.rr.com
http://www.cocopedia.com/wiki/index.php/Kip_Koon



> -----Original Message-----
> From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of Robert Gault
> Sent: Tuesday, September 01, 2015 9:38 AM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] VCC and HDBDOS
> 
> Kip Koon wrote:
> > Hi Robert,
> > I perused your web site a few days ago and found that I was confused as to which version of RGBDOS I need for VCC 2.00.  Of all the
> RGBDOS rom files I saw, I could not find one for VCC.  Maybe I missed something in my search.  Thanks for any help you can give.
> >
> > Kip Koon
> > computerdoc at sc.rr.com
> > http://www.cocopedia.com/wiki/index.php/Kip_Koon
> >
> Kip,
> 
>   There are very few differences amongst the "versions" of RGBDOS. The primary one is that some emulators require a ROM header
> indicating where the ROM should load into memory. All of the JVC emulators require a two byte prefix in Intel format equal to the
> load address. For example, a disk.rom must start with $00C0.
>   All the other emulators Keil, MESS, VCC expect an exact copy of the ROMS without any prefix.
> 
>   There are some other differences in how closely an emulator matches a floppy drive. On a real Coco, if you change the drive table
> from $1,$2,$4,$40 to
> $1,$2,$41,$42 you change from four single sided drives to two double sided drives.
>   When Joseph incorporated RGBDOS into VCC, he used a RGBDOS version that was set for double sided drives and had to change back
> to the original single sided table.
> 
>   There is a difference between VCC and the JVC, MESS emulators in that VCC mounts a single .vhd hard drive while JVC and MESS can
> mount two. There are different versions of RGBDOS for handle that.
> 
>   One final problem occurs if you want to use VCC with Drivewire. For that, VCC must be set to use hdbdw3bc3.rom rather than
> rgbdos.rom.
> 
>   Some of these issues occur when using RGBDOS/HDBDOS on real Coco hardware and get more complex when adding a CocoSDC or
> similar hardware.
> 
>   As far as VCC 2.xx goes, you want a version for a single .vhd hard drive with an offset of $5A000 at $D938. It won't hurt to have the
> two .vhd drive version as you are not likely to use the command to switch .vhd drives.
>   The ROM image should NOT have the two byte header. It should start with the typical DK.
> 
> ==========
> If you can't get a version to work or you have problems, contact me directly and I'll try to send you something that does work.
> If you just enjoy tinkering :) you can extract RGBDOS from the older versions of fd502.dll where the ROM starts at byte $12030
> through $14030.
> 
> Robert
> 
> 
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