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GNU LD the linker from hell

30th July 2008 @ 00:55:15 GMT

A fellow OS developer got in contact with me because he was having issues with his first OS.

So, this is a small setup just the basic multiboot structure and some simple C code that would call a C version of memset to fill the video memory with some letters. So a simple functionality and boot test.

I know your thinking, hmm not much that can go wrong. Wrong
But this just reinstates the quote

"Exercise caution in your programming;
for the OS is full of weirdness"

It took about an hours worth of debugging to find out that all the code was correct all the build files such as linker script and makefile are all pretty much correct, nothing wrong that would cause this problem. Analysis of the GCC output object files for the C code shows the compliation was perfect. Analysis of the final binary showed that LD just seemed to want to add 0x18 to every call displacement for no apparent reason.. It turn's out that the problem was conflicting packages downloaded from the DJGPP FTP site.

So please people, if you decide to start OS development please use a preprepared install of DJGPP. For those of you who want one you can find it: http://www.blackcore.co.uk/resources/djgpp.zip.

Napalm

Homemade Games Console

28th July 2008 @ 13:55:21 GMT

So, it's been a little while since I updated my blog so I hope this might make up for it. A couple of days ago I put the final touches to my games console.

Some of its features follow:

• The unit is 5V DC regulated.
• Its running a Parallax SX-28 Micro-processor @ 80MHz which has 128x 8bit of RAM and 2048x 12bit FLASH memory and 20 I/O pins.
• These I/O pins are separated in to 3 registers/ports 1x 4bit Port-A, 2x 8bit Port-B and Port-C.
• Port-A is connected up to 4 LEDs and a 7-segment LED display.
• Five pins of Port-B are connected up to 5 push buttons arranged in up/down/left/right and fire arrangement, which leaves 3 pins free for expansion. Port-B is also attached to the DB9 connector at the front for connection to a Atari style joystick.
• Each 4pins of Port-C connect to a R2R Ladder network of resistors to create a DAC(Digital to Analog Converter) with fine tuning potentiometers(variable resistors) attached to the output. These two DACs drive the audio and video RTA/Phono connectors.
• There is also and expansion header with 5V, Ground and Port-B attached to it.
• Finally we have a 4pin external serial programming connector and switches to control the power/programming/mpu-reset.

Click to enlarge.

Top right is small camera shot of one of my monitors showing a small test program which generates a composite PAL signal. At the moment I only have monochrome output but I am working on generating a colour PAL-B or PAL-I signal. I will keep you up to date with my progress.

Napalm

RCE Domain Names

2nd July 2008 @ 14:43:38 GMT

OK. I was thinking of getting another domain-name.. but I think I have too many as it is. I never end up renewing the ones I have so this list is pointless for myself.

So if anyone is looking for a RCE(Reverse Code Engineering) related domain-name these are available as of writing this.

(* means all TLDs including .*.uk)
• reverse-engineer.org.uk
• reverser.co.uk
• x86reversing.*
• x86.org.uk
• x86.me.uk
• x86rce.*
• codereverser.*
• rce1.co.uk
• opcode.org.uk
• opcode.me.uk
• opcodes.co.uk
• revcoding.com
• revcodes.co.uk

Napalm