[Coco] replacing main rom

jdaggett at gate.net jdaggett at gate.net
Thu May 12 16:54:08 EDT 2005


Thanks for the input and yes I am familiar with that part of the code. 

When this came up about a rom change and the GIME interrupts it 
spurred one of my lingering problems with the GIME FPAG project 
that I am working on. The timer. No where in the basic code is it 
used and even with the hardware character blick I anm not so 
certain that it is used for that. It maybe however that the blink timer 
and 12 bit timer at $FF94/$FF95 share the same frequency source 
and prescalar. 

Oh well even with the enhancements, I am postive that there is still 
some backward compatibility.


On 11 May 2005 at 21:06, William Astle wrote:

Date sent:      	Wed, 11 May 2005 21:06:44 -0600
From:           	William Astle <lost at l-w.ca>
To:             	CoCoList for Color Computer Enthusiasts 
<coco at maltedmedia.com>
Subject:        	Re: [Coco] replacing main rom
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> Someone else already pointed out that you can demonstrate that the
> character blink rate is determined by the timer. The timer itself has
> two possible input frequencies which correspond to the vertical and
> horizontal syncs (IIRC).
> The cursor blink is done in the "console in" routine which is
> "patched" by Super Extended basic to handle blinking the cursor on the
> hires text screen. It doesn't do anything so clever as count
> interrupts or anything like that to blink the cursor. IIRC it's merely
> Y times through the "wait for a keypress" loop then flip the cursor.
> Lather, rinse, repeat. Just like on the 32 column screen, just with
> only 2 states. You can demonstrate that it doesn't count interrupts or
> anything so clever by switching to high speed mode and you'll see the
> cursor blink rate doubles.

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