Re: [Ql-Users] QL MODE 8 Flash Bit

[Jan Bredenbeek via Ql-Users]

On 27 October 2017 at 21:51, Peter Graf  wrote:

> I just noticed the work was in vain, because SMSQ/E does not seem to
> support FLASH in MODE 8. At least not if I test with SBASIC.
>

Indeed SMSQ/E on a QL with Gold Card doesn't flash :(.
It also seems to work only when PRINTing something, not with graphics
commands (even not with BLOCK and CIRCLE).
It should be fairly easy to implement when PRINTing text since only the
flash bit of the first and last pixel of the printed pattern in each line
has to be set.

I've written it myself back in the '80s in a Videotex terminal program.
Since this uses block graphics which use the full 6x10 character matrix I
couldn't use the QL's screen driver and had to write one myself. One of the
challenges indeed was to implement flash when there was no 'spare' pixel
available for the background colour (which could occur in 'graphics hold'
mode) - in that case the only option was to clear the leftmost pixel which
was a slight deviation from the standard, but fortunately very rarely
visible.

Jan.

-- 
*Jan Bredenbeek* | Hilversum, NL | j...@bredenbeek.net
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Re: [Ql-Users] QL MODE 8 Flash Bit

[Dave Park via Ql-Users]

The flash bit acts as half a toggle for latching of the BGCOLOR in the
8301, ANDed with the other component, the 1Hz clock.

On Fri, Oct 27, 2017 at 2:42 PM, Jan Bredenbeek via Ql-Users <
ql-users@lists.q-v-d.com> wrote:

> On 27 October 2017 at 21:03, Peter Graf  wrote:
>
> > > E.g. when a pixel has red colour with flash on, the rest of the pixels
> > > on the line will flash between the original pixel colour and red until
> > > the next set flash bit.
> >
> > The "until" is ambiguous. When that next pixel occurs, does it still use
> > the background colour of the previous pixels, or already the colour in
> > it's own colour bits?
> >
>
> The flashing is up to and including the pixel which has the flash bit on to
> turn flash off.
> This can be seen when PRINTing something with flash on. Each character is 6
> bits wide, but only the least significant ('rightmost') 5 bits are used as
> the leftmost bit is always 0. This is the bit used to turn flash on, and
> when flash is on the flash bit of the LSB (rightmost) bit is also on so
> flash is turned off after each character (even when you print multiple
> characters on the same line).
>
>
> > Also, is there any exact info about the blink frequency?
>
>
> I've tested this on a real QL and it looks like the blink frequency is
> 16/50th of a second which is a bit slower than the software-generated
> blinking of the window's cursor (12/50th second). So a complete blink cycle
> will be 32/50th second.
>
> Jan.
>
> --
> *Jan Bredenbeek* | Hilversum, NL | j...@bredenbeek.net
> ___
> QL-Users Mailing List
>



-- 
Dave Park
d...@sinclairql.com
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Re: [Ql-Users] QL MODE 8 Flash Bit

[Peter Graf via Ql-Users]

Hi Jan,

> The flashing is up to and including the pixel which has the flash bit on
> to turn flash off.

Thanks for this precise info!

> I've tested this on a real QL and it looks like the blink frequency is
> 16/50th of a second which is a bit slower than the software-generated
> blinking of the window's cursor (12/50th second). So a complete blink
> cycle will be 32/50th second.

Thanks. I just measured exactly the same with a stop watch.

I alread have a hardware implementation now. Not just as easy when a
pixel really consists of 12 pixels...

I just noticed the work was in vain, because SMSQ/E does not seem to
support FLASH in MODE 8. At least not if I test with SBASIC.

All the best
Peter
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Re: [Ql-Users] QL MODE 8 Flash Bit

[Jan Bredenbeek via Ql-Users]

On 27 October 2017 at 21:03, Peter Graf  wrote:

> > E.g. when a pixel has red colour with flash on, the rest of the pixels
> > on the line will flash between the original pixel colour and red until
> > the next set flash bit.
>
> The "until" is ambiguous. When that next pixel occurs, does it still use
> the background colour of the previous pixels, or already the colour in
> it's own colour bits?
>

The flashing is up to and including the pixel which has the flash bit on to
turn flash off.
This can be seen when PRINTing something with flash on. Each character is 6
bits wide, but only the least significant ('rightmost') 5 bits are used as
the leftmost bit is always 0. This is the bit used to turn flash on, and
when flash is on the flash bit of the LSB (rightmost) bit is also on so
flash is turned off after each character (even when you print multiple
characters on the same line).


> Also, is there any exact info about the blink frequency?


I've tested this on a real QL and it looks like the blink frequency is
16/50th of a second which is a bit slower than the software-generated
blinking of the window's cursor (12/50th second). So a complete blink cycle
will be 32/50th second.

Jan.

-- 
*Jan Bredenbeek* | Hilversum, NL | j...@bredenbeek.net
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Re: [Ql-Users] QL MODE 8 Flash Bit

[Peter Graf via Ql-Users]

Hi Jan,

> It works in a serial fashion, much like the old Videotex/Prestel standard.
> When you set the flash bit on a pixel, the colour of that pixel is used
> as background flash colour for the rest of the line until another flash
> bit on the same line is encountered.
> E.g. when a pixel has red colour with flash on, the rest of the pixels
> on the line will flash between the original pixel colour and red until
> the next set flash bit.

The "until" is ambiguous. When that next pixel occurs, does it still use
the background colour of the previous pixels, or already the colour in
it's own colour bits?

Also, is there any exact info about the blink frequency?

> Hope you'll find this useful.

It is useful, thanks! But not yet sufficient for the implementation.

Peter
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Re: [Ql-Users] QL MODE 8 Flash Bit

[Jan Bredenbeek via Ql-Users]

On 27 October 2017 at 19:01, Peter Graf via Ql-Users <
ql-users@lists.q-v-d.com> wrote:

> Hi,
>
> today I noticed that my MODE 8 Flash Bit implementation in the Q68 was
> never completed. It is 11 years ago that I designed the video
> controller, and now I don't even remember how exactly the QL hardware
> used that bit at all. Especially, I don't know how the background colour
> for the flashing area is determined!
>
> Could anyone enlighten me? Quick reply would be nice, release date
> nearing quickly...
>
> It works in a serial fashion, much like the old Videotex/Prestel standard.
When you set the flash bit on a pixel, the colour of that pixel is used as
background flash colour for the rest of the line until another flash bit on
the same line is encountered.
E.g. when a pixel has red colour with flash on, the rest of the pixels on
the line will flash between the original pixel colour and red until the
next set flash bit.
It does not propagate across pixel lines so at the beginning of a pixel
line flash is always off.

Hope you'll find this useful.

Regards, Jan.

-- 
*Jan Bredenbeek* | Hilversum, NL | j...@bredenbeek.net
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[Ql-Users] QL MODE 8 Flash Bit

[Peter Graf via Ql-Users]

Hi,

today I noticed that my MODE 8 Flash Bit implementation in the Q68 was
never completed. It is 11 years ago that I designed the video
controller, and now I don't even remember how exactly the QL hardware
used that bit at all. Especially, I don't know how the background colour
for the flashing area is determined!

Could anyone enlighten me? Quick reply would be nice, release date
nearing quickly...

All the best, Peter
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