[Coco] Re: Important Announcement: NitrOS-9 & 1986 GIME

[Charlie]

Day 3 and I'm booting Nitros9 just fine using the white 80 column window.
I could write down the model numbers on the chips in this Performance 
Peripherals upgrade if anyone cares.
I know this system did not boot with the standard 128K or the chips in my 
old PP 512K upgrade.

Charlie


"Robert Gault" <robert.gault at worldnet.att.net> wrote 
in message news:41628E16.5050803 at worldnet.att.net...
> This is a message for everyone who is unable to run NitrOS-9 on a Coco3 
> with a 1986 GIME chip.
>
> As background, there are two versions of the GIME, 1986 & 1987. The '86 
> chip was the cause for many articles on "sparklies" that plagued early 
> adopters of the Coco3. There were also problems with the verticle and 
> horizontal scroll registers. I just found out that it is next to 
> impossible to boot NitrOS-9 (any version) on an '86 GIME Coco3.
>
> There are several theories that try to explain this problem and present 
> ways to correct it. To date, none have been successful during my testing 
> of the problem. The short story is that there are mistakes in the circuits 
> of the '86 GIME that can't handle the stress of NitrOS-9 code. The strange 
> aspect of this problem is that occasionally the boot process completes and 
> NitrOS-9 then runs without problems.
>
> I have found a workaround that seems to give 100% success at booting 
> NitrOS-9 on an '86 GIME Coco3. Change the boot screen from 40 or 80 
> character width to 32. You can still boot to an 80 character wide /term as 
> this has no effect on stability. The boot screen is still in a Coco3 video 
> mode rather than Coco1, so why this works is still a mystery.
>
>                         !!!HOW TO DO IT!!!
> It is only necessary to change one byte in sector 1 of track 34 to get a 
> successful boot. This changes the module REL. Once booted, you can os9gen 
> a fresh boot disk from the current NitrOS-9 release using the rel_32 
> module if desired. Using the new module will then have the NITROS9 BOOT
>   (FAILED)
> message in the correct location on the screen. The one byte patch will 
> prevent the message from printing, although the diagnostics will still be 
> readable.
>
> Using either a PC disk editor, an OS-9 disk editor (dEd), or one for Disk 
> Basic, locate in T34S1 the bytes $6C 00 00 00 09 00 00 00 '0B or 03' and 
> '34 or 24'. It is the last byte in this sequence, $34 or $24, that needs 
> to be changed to $20. You don't need to bother with the crc bytes and once 
> booted you ought to create a new boot disk with a proper rel_32 module.
>
> If you don't have a disk editor for Disk Basic, you can manage the same 
> thing with DSKI$ and DSKO$
>
>
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