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DanBoris' Tech Blog

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Procedure Calls 1

Posted by DanBoris, 26 November 2009 · 83 views

Action

Let's take a break from looking at Action! math and take a look at procedure calls. We will start up with something that is trivially simple:

Proc test()
Return

Proc main()
   Test()
Return

[code]0E61: 4C 64 0E JMP $0E64

0E64: 60 RTS

0E65: 4C 68 0E JMP $0E68

0E68: 20 61 0E ...

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CARD Math Part 2

Posted by DanBoris, 17 November 2009 · 66 views

Action

In my last post I showed how the Action! compiler produces some pretty optimized code for CARD math under certain circumstances. This time I will show the more general case which should be pretty familiar to anyone who has done 6502 programming.

Here is the Action! program and it’s dis-assembly:

[code]
CARD I

PROC...

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CARD Math Part 1

Posted by DanBoris, 15 November 2009 · 47 views

Action

I can’t believe it’s been over a year since my last blog post, time sure does fly! I thought it was about time to get back to some posts and continue my Action! language topic.

Last time I talked about BYTE math, this time we will start looking at CARDinal math. In Action the CARD data type is a two byte unsigned value. Here is the first...

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7800 Sprites

Posted by DanBoris, 11 November 2008 · 79 views

One of the trickier parts of the 7800’s MARIA graphics chip is understanding how to setup the display lists and display list list (DL and DLL). Even trying to put a single sprite on the screen can be tricky. In this article I will explain how to setup these data structures to get a simple sprite on the screen.

In this example we will take a very...

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