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Model 1, Level 2 - info required

D

Dustym

Experienced Member
Joined
Sep 2, 2009
Messages
220
Location
Lincolnshire U.K.
Please can anyone help - is it possible, from within L2 on a M1, to access the information on how normal alpha/numeric characters that appear on the screen are 'build-up' to display.
For example, the letter S seems to be made up of tiny dots within a 7x5 matrix. Is it possible to find out which of the tiny dots are used, each time that character is displayed.

Thanks
Dustym
 
Hi Dusty.

No, it is not possible to access any point of the character matrix.

The text that is shown on the screen is stored in the ram memory of the computer.
Here is the location where the image of your screen is available.

To show it to you a second system access this memory and is reading this memory, see it as a
window over the memory.

The binary values of the characters are send to a device, character generator named.
This generator built tv lines to show on your screen. This means that on scanline 1 the top row of each character is shown as
a row of dots.
In this way all the other lines are build. The character generator takes care of the space between the characters
and add empty lines below characters.

That means that a dot of a character cannot be accessed by you, but is controlled by the character generator.
Most times the cursor is generated by the generator too.

Hans.
 
Last edited:
Hans01 said:
Hi Dusty.

No, it is not possible to access any point of the character matrix.

The text that is shown on the screen is stored in the ram memory of the computer.
Here is the location where the image of your screen is available.

To show it to you a second system access this memory and is reading this memory, see it as a
window over the memory.

The binary values of the characters are send to a device, character generator named.
This generator built tv lines to show on your screen. This means that on scanline 1 the top row of each character is shown as
a row of dots.
In this way all the other lines are build. The character generator takes care of the space between the characters
and add empty lines below characters.

That means that a dot of a character cannot be accessed by you, but is controlled by the character generator.
Most times the cursor is generated by the generator too.

Hans.
Click to expand...

thanks Hans, we are way over my knowledge level here!!
 
Audronic said:
@Dustym

I have just been working on a Model 1 working with the Micro-80 Character generator Kit

A link below to the Data sheet for the MCM6670-74 Chips with the info you require

https://www.dropbox.com/s/m3mhnhibz0wahkb/Character Gen.pdf

Edit" I have a BIN file of the Micro-80 Eprom Plus other info :-

https://www.dropbox.com/s/cz02jnzcx87hexh/For Dustym.zip

Edit 2 More Info

http://www.vintagecomputer.net/fjkraan/comp/trs80/grafix80/80grafix.html

Ray
Click to expand...

Thanks Ray and everyone who's emailed me too, as I said, it's getting a bit to 'clever' for me!!
 
Audronic said:
@Dustym

I have just been working on a Model 1 working with the Micro-80 Character generator Kit
A link below to the Data sheet for the MCM6670-74 Chips with the info you require
https://www.dropbox.com/s/m3mhnhibz0wahkb/Character Gen.pdf
Edit" I have a BIN file of the Micro-80 Eprom Plus other info :-
https://www.dropbox.com/s/cz02jnzcx87hexh/For Dustym.zip
Edit 2 More Info
http://www.vintagecomputer.net/fjkraan/comp/trs80/grafix80/80grafix.html
Ray
Click to expand...

Updated link as i cannot edit the post ?

https://www.dropbox.com/s/m9sdfl9zt4jtn7y/TRS-80 Character Gen MCM6670.zip?dl=0

Ray
 
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