Day: November 6, 2014

Historic memories: how to create a DOS executable in the EDIT.COM

This is an old trick I used to do in the EDIT.COM of DOS to impress my friends. I discovery that some binary instructions could be represented in the text editor.

This is the sequence to create an executable that prints the ALAN name:

ALT 180 // 180 = B4h = mov AH
ALT 02  // 2
ALT 178 // 178 = B2h = mov DL
A       // C
ALT 205 // 205 = CDh = INT
!       // ! = 33 = 21h
ALT 178 ...
ALT 205
ALT 178
ALT 205
ALT 178
ALT 205
ALT 180 // mov AH
L       // L = 4Ch 
ALT 205 // INT 21 => exit to DOS

This will generate this binary file sequence:

B4 02 B2 43 CD 21 B2 4C CD 21 B2 41 CD 21 B2 55
CD 21 B2 44 CD 21 B2 49 CD 21 B2 41 CD 21 B4 4C
CD 21

This assembly instructions are equivalent to assembly instruction:

MOV AH,02 ; To select subfunction 2, move the appropriate number, 2, to AH.
MOV DL,”A” ; In the interrupt list, it says that the character to output should be
INT 21h ; in register DL. So we move the character to DL.
; Finally when all the registers are set as required, we call the interrupt.

MOV AH,4Ch ; Select the subfunction
INT 21h ; Select a return value (optional but recommended)
; Call the DOS interrupt.


Using Blender to develop for 3D Printer

I’m developing a new project with more complex shapes and I need tight control over all meshes as accurate as possible. Initially I was planing to use FreeCAD, but my FreeCAD’s skill is limited.

Then I decide to test Blender to 3D printing. Fortunately since version 2.67 Blender has a native 3D Printing Toolbox. The Blender toolbox is useful to analyze your object before sending it to printer, this way you will save time and money.

I started reading this tutorial:

First thing you need to do is enable the 3D Print toolbox addon. It is not enabled by default, but it is just a preference checkbox. Easy, en?

A useful tutorial is this from Shapeways:

I still learning about using Blender for 3D Printing, but I decided to post these links here to help other people willing to use Blender.

Another good video tutorial: