commodore 8032 vga / ports to monitor

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commodore 8032 vga / ports to monitor

Didier Derny
I guess that for my vga board, all I need to monitor

is the write in CRTC  (to reconfigure the screen emulated in the propeller)

and the write in $FFF0 to detect when the screen or I/O area are
shadowed by the 64k extension ?


I've not seen anything else in PIA/VIA but I may have missed something

for me the 8032 it's quite old...


thanks





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Re: commodore 8032 vga / ports to monitor

MiaM
Den Sat, 24 Feb 2018 22:49:37 +0100 skrev didier derny
<[hidden email]>:

> I guess that for my vga board, all I need to monitor
>
> is the write in CRTC  (to reconfigure the screen emulated in the
> propeller)
>
> and the write in $FFF0 to detect when the screen or I/O area are
> shadowed by the 64k extension ?
>
>
> I've not seen anything else in PIA/VIA but I may have missed something
>
> for me the 8032 it's quite old...

There is the "killer poke" that turns the VSYNC detect input to an
output. On the oldest PETs the hardware did drive hard enough that this
didn't matter but it disabled the timing logic halting the cpu when
accessing video ram while video were displayed. On newer machines it
messes up VSYNC output.

Don't know if there is any use emulating that behavior.

P.S. if you want some ideas for feature creep you might want to have a
look at the various hires addons for PETs :)

--
(\_/) Copy the bunny to your mails to help
(O.o) him achieve world domination.
(> <) Come join the dark side.
/_|_\ We have cookies.

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Re: commodore 8032 vga / ports to monitor

Rhialto
On 25 February 2018 00:28:53 CET, Mia
>There is the "killer poke" that turns the VSYNC detect input to an
>output. On the oldest PETs the hardware did drive hard enough that this
>didn't matter but it disabled the timing logic halting the cpu when
>accessing video ram while video were displayed. On newer machines it
>messes up VSYNC output.

There was a loop in ROM that tested the bit and delayed until retrace. It was taken out later.


--
Sent from my Android device with K-9 . Please excuse my brevity.

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Re: commodore 8032 vga / ports to monitor

Didier Derny
In reply to this post by MiaM
thanks for the informations


I think I found a way to support from the original pet 2001 to the 8296

I'll configure initially for 40 columns (pet 2001)  mode   (color of the
screen / level with trim on the board)

then when I receive the crtc configuration I'll switch to the correct mode


Le 25/02/2018 à 00:28, Mia Magnusson a écrit :

> Den Sat, 24 Feb 2018 22:49:37 +0100 skrev didier derny
> <[hidden email]>:
>> I guess that for my vga board, all I need to monitor
>>
>> is the write in CRTC  (to reconfigure the screen emulated in the
>> propeller)
>>
>> and the write in $FFF0 to detect when the screen or I/O area are
>> shadowed by the 64k extension ?
>>
>>
>> I've not seen anything else in PIA/VIA but I may have missed something
>>
>> for me the 8032 it's quite old...
> There is the "killer poke" that turns the VSYNC detect input to an
> output. On the oldest PETs the hardware did drive hard enough that this
> didn't matter but it disabled the timing logic halting the cpu when
> accessing video ram while video were displayed. On newer machines it
> messes up VSYNC output.
>
> Don't know if there is any use emulating that behavior.
>
> P.S. if you want some ideas for feature creep you might want to have a
> look at the various hires addons for PETs :)
>


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Re: commodore 8032 vga / ports to monitor

Steve Gray
The problem with that is both 40 and 80 column screens are configured the same (as 40 column) since the 80-column circuitry does tricks to display 2 characters in the space of one.
You can identify european vs north american (50/60 hz power) by looking at the timing registers, but not 40 vs 80. You could monitor for writes to screen ram >1024 to indicate 80 column. this would be done at initialization to clear the screen.

Steve



From: didier derny <[hidden email]>
To: [hidden email]
Sent: Tuesday, February 27, 2018 6:30 AM
Subject: Re: commodore 8032 vga / ports to monitor

thanks for the informations


I think I found a way to support from the original pet 2001 to the 8296

I'll configure initially for 40 columns (pet 2001)  mode   (color of the
screen / level with trim on the board)

then when I receive the crtc configuration I'll switch to the correct mode


Le 25/02/2018 à 00:28, Mia Magnusson a écrit :
> Den Sat, 24 Feb 2018 22:49:37 +0100 skrev didier derny
>> I guess that for my vga board, all I need to monitor
>>
>> is the write in CRTC  (to reconfigure the screen emulated in the
>> propeller)
>>
>> and the write in $FFF0 to detect when the screen or I/O area are
>> shadowed by the 64k extension ?
>>
>>
>> I've not seen anything else in PIA/VIA but I may have missed something
>>
>> for me the 8032 it's quite old...
> There is the "killer poke" that turns the VSYNC detect input to an
> output. On the oldest PETs the hardware did drive hard enough that this
> didn't matter but it disabled the timing logic halting the cpu when
> accessing video ram while video were displayed. On newer machines it
> messes up VSYNC output.
>
> Don't know if there is any use emulating that behavior.
>
> P.S. if you want some ideas for feature creep you might want to have a
> look at the various hires addons for PETs :)
>


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Re: commodore 8032 vga / ports to monitor

Didier Derny

Hi Steve, 

thanks for the information

I guess I should plan some switches...

my main problem is the lack of pins on the propeller I'm almost using everything....

I also have a mechanical problem with the vga cable, it has a tendancy to remove the board out of the 6502 socket

for the next version I'll use a small connector with a small cable connected to the real vga plug

such a wat that if there is a traction the small connector disconnect without removing the board out of the 6502 socket






Le 27/02/2018 à 15:47, Steve Gray a écrit :
The problem with that is both 40 and 80 column screens are configured the same (as 40 column) since the 80-column circuitry does tricks to display 2 characters in the space of one.
You can identify european vs north american (50/60 hz power) by looking at the timing registers, but not 40 vs 80. You could monitor for writes to screen ram >1024 to indicate 80 column. this would be done at initialization to clear the screen.

Steve



From: didier derny [hidden email]
To: [hidden email]
Sent: Tuesday, February 27, 2018 6:30 AM
Subject: Re: commodore 8032 vga / ports to monitor

thanks for the informations


I think I found a way to support from the original pet 2001 to the 8296

I'll configure initially for 40 columns (pet 2001)  mode   (color of the
screen / level with trim on the board)

then when I receive the crtc configuration I'll switch to the correct mode


Le 25/02/2018 à 00:28, Mia Magnusson a écrit :
> Den Sat, 24 Feb 2018 22:49:37 +0100 skrev didier derny
>> I guess that for my vga board, all I need to monitor
>>
>> is the write in CRTC  (to reconfigure the screen emulated in the
>> propeller)
>>
>> and the write in $FFF0 to detect when the screen or I/O area are
>> shadowed by the 64k extension ?
>>
>>
>> I've not seen anything else in PIA/VIA but I may have missed something
>>
>> for me the 8032 it's quite old...
> There is the "killer poke" that turns the VSYNC detect input to an
> output. On the oldest PETs the hardware did drive hard enough that this
> didn't matter but it disabled the timing logic halting the cpu when
> accessing video ram while video were displayed. On newer machines it
> messes up VSYNC output.
>
> Don't know if there is any use emulating that behavior.
>
> P.S. if you want some ideas for feature creep you might want to have a
> look at the various hires addons for PETs :)
>


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