Re: PET Graphic, Font, 40/80, Composite and Audio Boards

From: Steve Gray <sjgray_at_rogers.com>
Date: Sat, 24 Mar 2018 00:21:39 +0000 (UTC)
Message-ID: <2044822350.105070.1521850899039@mail.yahoo.com>
No, the 8296 (and D) use exactly the same character rom. The 4000 and 8000 series machines can also do this 10-pixel tall character height thing. On all these PETs there is a little circuit that ensures that only the first 8 pixels are displayed and that the 2 extra lines (or more) are blank.
Steve

      From: Mia Magnusson <mia@plea.se>
 To: cbm-hackers@musoftware.de 
 Sent: Friday, March 23, 2018 8:16 PM
 Subject: Re: PET Graphic, Font, 40/80, Composite and Audio Boards
   
Den Fri, 23 Mar 2018 07:26:04 -0700 (MST) skrev vossi <vossi@ceffy.de>:
> I just checked my monitors. Before this I noticed only the light and
> dark green tubes!
> 
> You are right - the 8296D and the 7xx have the same monitor pcb (and
> the darkgreen tube).
> The 8096sk and the 8032sk have a different pcb and the light green
> tube. It's possible that the older monitor is not capable to display
> the 350 lines
> - I never tried it.
> 
> PS: with the hsg board installed I had to tune the picture-height in
> the sk to see the whole screen. On the 1702 external connected I have
> exactly a full screen pic with the hsg.

My 8296 (not D) uses 8 pixels high characters for upper case /
"graphics character" mode, and switches to insert some blank lines
between each character in lower case mode.

With 2 blank lines between each character row which itself is 8 video
lines, you get 25 rows of 10 video lines each, minus that you don't
need to show the two blank lines outside visible text, giving 248 lines
displayed on screen. With rather large borders it might be possible to
display 350 lines in that mode.

P.S. this must mean that 8296 has another ROM than the 8096 and 8032,
right?

I were so sure that all PETs used 15kHz monitors, and not the 18kHz
MDA/Hercules monitors. But my 8296 is suspiciously silent compared to
most 15kHz monitors, even smaller black and white, which usually
screams really annoyning at 15kHz.

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Received on 2018-03-24 02:04:30

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