Apple II checkerboard

I remember years ago I wanted to see what would happen if I flipped the Apple II's hi-res pages as fast as I could.

So I did an HGR which would clear the first hi res screen, then an HGR2 to switch to the second hi res screen and filled the screen with white with a for loop. Something like HCOLOR=7:FOR I = 0 TO 191:HPLOT 0,I TO 279,I:NEXT.

Then I entered a little machine language program that would read $c053 and $c054 to flip the pages, then jump back to the top of the loop.

As I recall, it would make a neat checkerboard effect, alternating black and white down the screen. If you altered the timing of the loop, the pattern would change.

Of course, this would necessitate a reset to get out of this loop.

This is all from memory, as I haven't had a real apple II for ages.

Little puzzles

Recently, I've been fascinated with LCDs and how to drive them from a microcontroller. They're not simple like LEDs, you have to give them an AC signal. If you drive them with a DC signal, it will destroy the LCD.

So I read a bunch of pages about driving LCDs searching google on "driving lcd microcontroller".

In the pdf at http://www.atmel.com/Images/doc2569.pdf it describes how you can make the necessary voltages to swing from -vlcd to +vlcd using waveforms that runs from 0 to +vlcd and are out of phase with one another.

This totally baffled me, how could you make the negative voltage differences with only positive voltage?

I was stumped before I realized that the negative voltage difference wasn't from COM to ground or SEG to ground but instead from COM to SEG.

When COM is +vlcd and SEG is 0, you get +vlcd across COM-SEG.

When COM is 0 and SEG is +vlcd you get -vlcd across COM-SEG.


This page was pretty helpful to see this:

http://www.arduinoos.com/2014/08/lcd-direct-driving/

I think I figured out why I like the original Stellar 7

So I'm looking at these screenshots of Stellar 7 and its remakes/sequels and I think I can see why I like the original. The viewscreen is bigger and fills up more of the screen space. In all of the remakes, the viewport is about half the size due to all of the cockpit graphics.

It makes the low resolution screen seem even more low resolution.

They also run too fast, somehow the slow frame rate makes the graphics easier for the eye to track.

This would be a fun project, to remake Stellar 7 with nice hi-res graphics in Blitz Basic or something.

Another game that would be a great remake with modern technology is Rescue Raiders.


A couple of great webpages on Stellar 7 with all kinds of nice screenshots:

http://www.hardcoregaming101.net/stellar7/stellar7.htm

https://www.c64-wiki.com/index.php/Stellar_7

Trying to find things that you've seen long ago

I watched this foreign French movie on Bravo years ago. I forgot the name of the movie and so I went looking for it on imdb. I wasn't able to figure it out initially but I never gave up and kept looking every time it popped into my head. Finally, I figured out what it was. It was called "Le the au harem d'Archimede" or "Tea in the harem". You know, the Theorem of Archimedes.

I remember these things long ago and can't remember what they were exactly.

Like this music video that I think aired on the show "Rock'n America" back in the 80s where this gal in this yellow jumpsuit was in some kind of power plant pulling levers up and down. I'm still trying to figure out what that one was. I vaguely remember it being called Love lines or something like that.

And this Othello game that I played years ago on some really fancy computer back in the mid 80s. I don't know what computer it was, but that was practically the only game for it and I remember that the computer was really expensive. It was some really obscure desktop computer with a monochrome display. I don't remember it having color. Someday I'll figure out what it was. I keep searching google images for Othello or Reversi but nothing looks familiar.

The obscure things that you remember and you want to put a name with them.

Inkjet printers drive me crazy

If you leave an inkjet printer idle for a couple of weeks, the cartridges tend to dry up. Then you get all of this streaky printing with missing lines.

I don't print all that much so this happens to me a lot. So at the precise moment I actually need my printer for something important, it doesn't print properly.

Most infuriating.

Finnix for powerpc imac g4

A friend gave me an old imac g4 with an ailing hard drive. How to image it? I would normally use knoppix, my favorite linux. But the imac g4 is powerpc, and knoppix is x86.

What to do? Well, there's a nice distribution called Finnix which is very knoppix-like and works with powerpc.

It seems to be text only, but that isn't a problem for me, as the programs that I'm interested in are things like ddrescue, smartctl, and mount.cifs.

So far, it works great!

My knoppix flash drive install seems to get slower and slower

I like to run a knoppix system off of a flash drive, but it has tended to get slower and slower over time.

Perhaps I just don't have enough memory on this old notebook (it only has 2GB).

Maybe the iceweasel/firefox history files get too big. I like keeping my history though.

I see the flash drive flicker quite a bit at times and sometimes iceweasel will just take forever to load a page.

It does run though and will return to normal eventually.


edit: Maybe the flash drive is a little bit screwy. I had to fix some corruption in the persistent image with fsck.ext2. Also there was some corruption in the vfat partition where knoppix-data.img resides that fsck.vfat couldn't fix. It told me the fat table and the backup didn't match and presented me with options to take one or the other, but no matter which one I chose, it wouldn't make any modifications.