[Coco] OS-9 Level1 Version 02.00.00 FYI

[Dave Philipsen]

Could be. But I can tell you that the way the interrupts are serviced is different between L1 and L2. L2 receives the interrupt from the GIME while L1 receives it from the PIA.  The source of the interrupts is the same; vertical interval. But I’m not into emulators so I have no real desire to try to figure out what the problem is. The only time I ever ran an emulator was probably 7-8 years ago when I tried VCC. But it never impressed me that much.

Dave

> On Apr 17, 2020, at 10:42 AM, Bill Pierce via Coco <coco at maltedmedia.com> wrote:
> 
> Dave, it seems it's something involving what OS9 L1 does immediately after a key is pressed. Programs seem to run fine up to a key press. L1 v2.0 must do something different right after the key press as opposed to L2. This difference is triggering VCC to freeze. I assume some reg is being reset and VCC is not responding properly. The object would be to trace down what happens after a keypress, step by step, in both L1 & L2. This should tell us what L1 is stomping in VCC and then we could fix VCC.
> 
> 
> -----Original Message-----
> From: Dave Philipsen <dave at davebiz.com>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Sent: Fri, Apr 17, 2020 11:10 am
> Subject: Re: [Coco] OS-9 Level1 Version 02.00.00 FYI
> 
> Actually keyboard interrupts are not used in OS9. The keyboard is scanned at a regular interval determined by the interrupt routine but it’s actually the video system which is generating the interrupts which OS9 also uses for multitasking.
> 
> Dave
> 
> 
> 
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