System disk 004. Working with the video

Dinkit 004 (System disk 004) now has IO (input/output)!  Called “VID_BIOS”, will OK, that is just output only.  Fine! Dinkit 004 now just has two outs only ! Sound and video. A new tool (subroutines) was added to the kernels basic core called "Vid_bios". This is a not so standard “video-bios” subroutines that provides the display of all 255 chars. and all 16 bit color any where on a 25X80 display. However You will not be to happy with this bios call in that you will have to input the chars. one at a time and backwards and you are limited to 255 chars max!  You can intermix " S_wait" with "Vid_bios" to slow it way down to see just how the back ward display works.

Where is the key board?  Coming  later.  There much to do before we get to the key board. There are a few more tools to be added that are more important than the key board.

What you will learn

The main lesson is learning three new lines of code (video out). It takes the 3 lines of code to display 1 char. You use the 3 lines over and over for each char. to be displayed. The lines of code are almost the same  except for the char. and the count. Most newbies find it hard to understand why it is necessary to type in the char (S) backwards. You will find a great demo in system disk 5

 Use  for “System disk 4”

Make a bootable disk the will display a line of text that is under 255 car.(s) The OS system is about 750 byte plus the 255 bytes for text. A little over 1k in size. So 2K of memory will do the job. So this disk will run on any PC type computer. The first IBM PC bare bones came with 16k of memory

Download “System Disk 4”

Go to the download page and click on the “System disk 004” link