Typing inverse characters

ChrisF · Post by **ChrisF** » Thu Oct 30, 2008 1:13 pm

Hello world,
I'm new to the VIC20. Back in the day it was a but before my time (my first computer was a Spectrum+2). Anyway, I bought a VIC to see how Jetpac compared to the Spectrum version, and then I found it was rather nice to type on so I decided to try some typeins I found on the net. Unfortunately, most of them contain inverse characters and I can't work out how to type them (my computer is in perfect working condition as far as I can tell, but it didn't come with any manuals, so forgive me if I'm asking something really basic and silly). Can somebody out there put me out of my misery please?
cheers
Chris

ral-clan · Post by **ral-clan** » Thu Oct 30, 2008 8:30 pm

The inverse characters are special control characters that tell the VIC to do something like move a cursor in a specific direction, or change the colour of the output in a print statement when the program is RUN.

Most are obtained by pressing either SHIFT or the Commodore key at the same time you press a colour key (numbers 1 to 9?) or one of the cursor directional keys. Revers Video control characters can also be obtained this way (on the right side, top row, a little past the number characters....can't remember exactly which keys now).

Most of them will only show up after you have typed the first quotation marks in a PRINT or INPUT statement. Play around with them this way and you will so be able to tell which is which. In fact, COMPUTE! magazine always had a page telling you which was which....so if you can find a COMPUTE! magazine archive online, I'm sure you'll be able to find this page.

orion70 · Post by **orion70** » Fri Oct 31, 2008 1:28 am

Post by **Jeff-20** » Fri Oct 31, 2008 1:58 am

I really wish we had a scan of that page somewhere on the wiki. I have it. I know. I'll have to find it.

Post by **Jeff-20** » Fri Oct 31, 2008 1:59 am

beat me by seconds.

ral-clan · Post by **ral-clan** » Fri Oct 31, 2008 8:26 am

Jeff-20 wrote:I really wish we had a scan of that page somewhere on the wiki.

Done.

http://sleepingelephant.com/denial/wiki ... characters

Boray · Post by **Boray** » Fri Oct 31, 2008 8:35 am

But the commodore + 1 to 8 combinations doesn't work on vic-20... That's for c64 etc...

ral-clan · Post by **ral-clan** » Fri Oct 31, 2008 8:47 am

Boray wrote:But the commodore + 1 to 8 combinations doesn't work on vic-20... That's for c64 etc...

Thanks for that info....added to Wiki article.

ChrisF · Post by **ChrisF** » Fri Oct 31, 2008 11:21 am

Thanks, that was what I needed to know.
cheers
Chris

carlsson · Post by **carlsson** » Fri Oct 31, 2008 12:46 pm

As a side note, on the C64 you can hold CTRL and press any letter except M to get that one inversed within quotes. Those extra control codes work on a VIC-20 too, just that it doesn't allow you to type them in that way. I suppose that difference lays within the Kernel, not Basic ROM?

An alternative way to get control codes:
1. PRINT""
2. Delete the last quote character
3. Press CTRL+9 (RVS ON)
4. Type the desired control code character
5. Press CTRL+0 (RVS OFF)
6. If you want to stay in quote mode, make one " and go on
7. If you want to end the PRINT statement, make two "" and delete one

Perhaps it sounds more complicated than it is.

Now you may ask what nice little secrets you can obtain. Here is a possibly incomplete list, where CTRL is used to clarify it is a control code:

CTRL+E : White text (duh)
CTRL+H : Locks switching upper/lower case (C= + SHIFT)
CTRL+I : Unlocks case switching
CTRL+M : Carriage return, will be converted to a such in listings
CTRL+N : Switch to lower case
CTRL+Q : Cursor down (duh)
CTRL+R : RVS ON (duh)
CTRL+S : Home cursor (duh)
CTRL+SHIFT+N : Switch to upper case
CTRL+SHIFT+P : Black text
CTRL+SHIFT+Q : Cursor up
CTRL+SHIFT+R : RVS OFF
CTRL+SHIFT+S : Clear screen

All those can of course be obtained with CHR$ codes too, but it may look more cool to include them as control codes in a PRINT statement. It can also save a few bytes in tight cases. In particular CTRL+H and CTRL+N may be nice in a program where you use Upper + Lower case and don't want the user to switch to the graphics character set.

ral-clan · Post by **ral-clan** » Fri Oct 31, 2008 12:59 pm

Thanks Carlsson, that info has been added to the Wiki article.

Post by **Jeff-20** » Fri Oct 31, 2008 2:25 pm

Is there a CTRL code to insert large spaces, something equivalent to a TAB(X)? I remember looking at the LISTing of Blue Meanies from Outer Space once. They inserted huge spaces for fewer bytes than a SPC or TAB command.

carlsson · Post by **carlsson** » Fri Oct 31, 2008 3:19 pm

I can't think of anything like that. I downloaded Blue Meanies and I believe it is this line you refer to:

4 PRINT:PRINT:PRINT"{4 SPC}{RVS ON}{14 SPC}{RVS OFF}":PRINT"{4 SPC}{RVS ON} BLUE MEANIES {RVS OFF}":PRINT"{4 SPC}{RVS ON}{14 SPC}{RVS OFF}"

That line expands to 97 characters, or almost 4.5 rows. The trick to fit it all in one line is of course to use ? for PRINT when you enter it, only 77 characters out of a maximum of 88.

On the C64 there were small hacks that lets you enter a Basic line up to 255 characters. I believe those exist for the VIC too, or at least would be easy to convert if desired. I remember the topic has been up to discussion before.

Duane Later has squeezed several lines > 88 characters into Blue Meanies, probably by using plenty of abbreviated keywords. The drawback is that a such line is much harder to edit if you need to fix something.