ERIC SHEFFERMAN <DOT> COM

Blog-o-Goodness

FREE Website Uptime Monitoring

There is a LOT that can be done with free online services — sometimes things that probably go way beyond what the service creators envisioned.

Read the rest of this entry »

Share

Pardon the 6502 Interrupt: PHA TXA PHA TYA PHA

Yes, I still think in 6502 code.

I was looking at a video of the Atari 7800 game Ikari Warriors — a game that I worked on back in the 1980’s.

I was the one who suggested to Mike a way to build a board to install our own development system operating system on the Atari 7800 — which we then later turned into a NES development system (which made it about $10,000 cheaper than the official Nintendo developer system).

And I wrote the interrupt-driven code for the development system so that we could debug WHILE the game was playing on the system. The 7800 was connected to an IBM PC (compatible) (and probably running something super-powerful like a 8086 or maybe a 286). We wrote the code and compiled it on the PC and then transferred it over to RAM we had installed on the 7800 to simulate a ROM cartridge. The PC could issue commands to the development system which were processed on the interrupts so that we could debug in real time.

Big lesson learned — there’s no point in trying to save every last CPU cycle.

PHA 
TXA 
PHA

Winds up functioning very differently from

PHA 
TXA  
PHA 
TYA 
PHA

as the start of your interrupt code. Especially after a few months when you forget what you wrote and add in some feature that uses the Y register.

Oh so many bizarro errors that caused that were impossible to track.

Lesson learned.

I was very pleased with myself at how I had designed the game engine to make the bad guys move in zones, thus allowing sprites to be reused in multiple zones and thus allowing there to be a ton of objects moving on the screen at any time. No big deal now, but BIG DEAL back then.

I didn’t get to work on the final gameplay stuff since we then used our ability to make development systems to move on to doing Nintendo programming rather than finishing the game. It doesn’t look to me like it plays as smoothly as it had potential to.

 

Share

Cartoon That Explains Space Invaders

I remember Space Invaders well. It was the beginning of a whole new era — right at the start of high school. Video games had arrived and lunchtime involved playing Space Invaders, Asteroids, and then Pac Man and so on.

But where did those Space Invaders come from? Why were they invading? What were their motivations? Nobody knew.

Until now…

Read this comic and find out:

http://elcomics.tumblr.com/

Share

Problem accessing secure pages and other web pages on amazon newegg and more

For a week or two (I’m pretty sure this started before Hurricane Irene) I’ve been having trouble accessing secure pages on amazon.com. I can’t see my past orders, reach my Amazon Cloud Drive, or now even place a new order. I discovered today that I can’t get the newegg.com site to work either — so I’ve got no way to order computer stuff I need.

At first I thought it was something corrupted on my main computer.

I’ve tried Internet Explorer, Firefox, and Safari browsers. Then I tried my older computer that’s running Linux. I’ve tried my laptop.

Nothing works. On amazon and newegg I can’t access any page that’s secure.

Read the rest of this entry »

Share

APC UPS Fails When The Battery Is Dead

Friday night I was getting ready to go out to see Marshall Tucker and Kansas at a free concert in Eisenhower Park. I was trying to figure out what to bring with me since it was supposed to be thunderstorms… and the lights all go out.

So now the only light in my room is the light from my monitor, thanks to my APC BX1300LCD. So I go over to my computer to hibernate it, since I was going out and wouldn’t be needing it on anyway.

I reach for the mouse and… the screen goes dark and I hear the computer fans whirring down.

So now I’m standing in darkness. My first thought is, I’d better go turn on the lights! Then I realized, the light switch probably wasn’t going to help.

Argh. So I searched for my flashlight, grabbed whatever seemed like it would be useful, and left.

Read the rest of this entry »

Share

OCR is super powerful now — and free

I found a printout of a webpage that is long since gone (and not archived at http://www.archive.org — that would have been too easy).

So what to do? Scan it in and use Optical Character Recognition (OCR) software.

Um, but I don’t have any software like that and I’d rather not buy any.

Read the rest of this entry »

Share

I have always depended on the kindness of strangers.

I stumbled across this site quite accidentally. It’s about an experiment with cute little robots that are fairly helpless and seeing what happened when they relied on the kindness of strangers to get where they were supposed to go.

The creator of the experiment made the robots as cheaply as possible — expecting them to meet their doom in the cruel, cruel world — but was pleased to find that even in New York city there were strangers who were willing to help a little defenseless robot.

Read the rest of this entry »

Share

Keep Up With
Eric Shefferman

Via RSS
    

Via Email Updates
Name:
Email:

Categories

Archives

The following link is not for people: I do not like it, Sam I Am.