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PET 8032-SK space between character lines

C

CurtisN

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Dec 21, 2017
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Location
Netherlands
Hi all,

New to the forum. I'm based in the Netherlands and I'm a bit of a Commodore enthusiast. One of my prized posessions is a 8032-SK. I have owned it for almost 8 years, but never really had the room to properly set it up and use it. I do now! And I'm trying to get more familiar with this wonderful machine.

I understand that the 80 column display is not the best option when it comes to available games for the PET, but I don't really mind that much. What did bug me though was when I was playing around with PETSCII graphic characters. I quickly noticed there's a margin of maybe one or two pixels between each line of the display. If I print out reversed spaces on the C64 I can fill the whole screen, but with the 8032-SK I get black lines between every line. I guess it's best to illustrate with a photo:

IMG_0182.jpg

Is there any way to change the display so that each line is connected to the line above and below it or is this just the way that the display works on 80 column machines? Thanks in advance!
 
CurtisN said:
Is there any way to change the display so that each line is connected to the line above and below it or is this just the way that the display works on 80 column machines? Thanks in advance!
Click to expand...

I think it is that way in 40 or 80 column PETs. If each line were connected, would not the text look awful?

There is a program called something like 'CBM4032' that if run before a game is loaded into an 8032, will use the middle 40 columns so games display correctly. Games must be for BASIC 4.

Steve Gray has a way to create a custom ROM image to burn into a modified EDIT ROM which, among many other features, will allow a soft switch between 40 and 80 column screen output.
See: http://www.6502.org/users/sjgray/projects/editrom/
 
My 40 column does not do this (nor do Vic20s with that font IIRC). I'm wondering if my B128 does this.

I don't know how the graphic characters could possibly work right with that space. I wonder if this is a difference between machines with graphics on the keyboard or not.

Also I wonder if this space is in the character ROM or in the display generator.
 
80 column machines start in “text” mode with each line being 10 pixels (scanlines) tall. It is supposed to make text easier to read by adding 2 blank scanlines so that descenders do not touch the text below.
You can switch to “graphic mode” to eliminate the spacing. Basically you print chr$(14) or chr$(142) to switch between modes.

If you want to build a custom editor rom using my project you could have it start in graphic mode. It is very customizable ;-)

Steve
 
KC9UDX said:
My 40 column does not do this (nor do Vic20s with that font IIRC). I'm wondering if my B128 does this.

I don't know how the graphic characters could possibly work right with that space. I wonder if this is a difference between machines with graphics on the keyboard or not.

Also I wonder if this space is in the character ROM or in the display generator.
Click to expand...

Its in the CRTC controller settings. You can program it to display up to 32 scan lines per text line. However, in the PET there is built-in circuitry to make sure only the first 8 scanlines appear.

Steve
 
Hallo,

Hartelijk welkom hier!

FYI, on every third Saturday of the even month there is a Commodore user group meeting in Maarssen, Kerkweg 17. Next one is 17 februari.
If interested, you are welcome!

Kind regards/met vriendelijke groet, Ruud Baltissen
www.baltissen.org
 
sjgray said:
You can switch to “graphic mode” to eliminate the spacing. Basically you print chr$(14) or chr$(142) to switch between modes.
Steve
Click to expand...

Wow! Thank you, Steve! That did the trick. I was doing POKE 59468,12 and POKE 59468,14 to switch between modes, but that left the extra 2 scanlines in between. Being able to switch between these combinations is the best of both worlds! Thanks again.
 
Hartelijk dank voor dit. Kennen jullie ook hoe je de graphics mode aan / uit via ?chr$(142) / ?chr$(14) kan bereiken via poke commands?

Thanks for this information. Do you also know how to achieve the graphics mode effect on / off via ?chr$(142) / ?chr$(14), but through poke commands?

I own a commodore 8032 PET (the round one).
 
Easiest way is using a disk emulator, problem is they are inevitably made to fit the GPIB the edge connector rather than the SK's actual GPIB connector and while the edge connector is actually there inside the case, there isn't enough room to fit standard 8032 solutions.

I use my own unit based on an Arduino mega.

One of the PetSD's would be perfect for the SK as they came with the right connector, but they are no longer sold I believe.

Of course a Tapuino should work.
 
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Thinking outside of the box (literally) there are disk emulators for the Tektronix 405x that have been developed.

These have a 'real' GPIB connector on them.

I wonder if the firmware could be re-jigged for the PET? I know it can of course. The question is whether anyone would want to take the project on...

Dave
 
CurtisN said:
Hi all,

New to the forum. I'm based in the Netherlands and I'm a bit of a Commodore enthusiast. One of my prized posessions is a 8032-SK. I have owned it for almost 8 years, but never really had the room to properly set it up and use it. I do now! And I'm trying to get more familiar with this wonderful machine.

I understand that the 80 column display is not the best option when it comes to available games for the PET, but I don't really mind that much. What did bug me though was when I was playing around with PETSCII graphic characters. I quickly noticed there's a margin of maybe one or two pixels between each line of the display. If I print out reversed spaces on the C64 I can fill the whole screen, but with the 8032-SK I get black lines between every line. I guess it's best to illustrate with a photo:

View attachment 1059152

Is there any way to change the display so that each line is connected to the line above and below it or is this just the way that the display works on 80 column machines? Thanks in advance!
Click to expand...

I've had had the same issue and the question posted here was not answered completely.
One cannot simply adjust the display with a simple poke, as the CRTC needs to be adjusted as well.
And using chrout kernal api is cumbersome ...

I've been checking the disassembly of the BASIC 4.0 ROM and I think I found a more lean way to do this.
Just by typing sys 57474 (jsr $E082) the CRTC is set to work with 8 lines per character line.

Typing sys 57466 (jsr $E07A) resets the CRTC, inserting 2 scan lines between each character line, thus 10 scan lines in total.

Hope this helped!
 
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