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We appreciate Ron Mitchell sharing this information with us. 

 
 
VRAMREADER 
 
by R.H. Mitchell 
 
This little program will enlighten and entertain...(I hope). IARTICLE BY RON MITCHELL, PRESIDENT OF AUFG (Adam User Friendly Group) of Ontario Canada. 
 
We appreciate Ron Mitchell sharing this information with us. 

 
 
VRAMREADER 
 
by R.H. Mitchell 
 
This little program will enlighten and entertain...(I hope). It's purpose is to show you the coding contained in ADAM's video ram (VRAM) and in doing so permit you to see exactly how the character set is formed. 

A couple of issues ago, you'll recall that we discussed the formation of one character using a grid of eight bytes. In fact the character itself used a 5 by 7 pixel grid with the rest providing spacing in between the characters. Well here's the entire set, and if you want to get highly ambitious, you can even use the information provided to re-write your own character set. 
 
The program will read the byte pattern in each of the 16384 VRAM addresses, and give you a choice of output. If you select the hex mode, you get a straight printout of the hex value at each VRAM address. Not too informative, I thought, so I decided to add a binary conversion routine, and do a little setting up on the screen. Selecting a binary readout will convert each of the VRAM bytes into binary and if you take them in groups of 8 over the first few pages, you'll see how each of the characters is formed. Aside each byte's binary printout is the ASCII character that byte is part of, the decimal equivalent of the binary value, and the VRAM address where it is stored. To read another byte, simply press return. To leave the program, press the escape key. 
 
Enjoy. Here's the printout. 
 
SEE VRREAD File. 
 
en the char
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