The Dragon Font and lowercase characters

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jedie
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The Dragon Font and lowercase characters

Post by jedie »

In the XRoar sources I found these font files:

font-6847.png
Image
https://github.com/jedie/XRoar/blob/mas ... t-6847.png

font-6847t1.png
Image
https://github.com/jedie/XRoar/blob/mas ... 6847t1.png

I think font-6847.png is the Dragon 32 Font, isn't it?
But why are there lowercase characters? Does the ROM of the MC6847 chip really contains the two bottom character lines and the Dragon 32 ROM simply doesn't use it?
Exit there a way to output these characters?

I have created http://archive.worldofdragon.org/index. ... le=CharMap in the past.

I created the followed screenshot with this simple BASIC test code:

Code: Select all

10 CLS
20 FOR I = 0 TO 255:
30 POKE 1024+(I*2),I
40 NEXT I
50 I$ = INKEY$:IF I$="" THEN 50
Image

Next Questions: Where are the colored semigraphic charactes stored?
... too many ideas and too little time ... Related stuff written in Python:
Dragon 32 emulator / PyDC - Python Dragon 32 converter: https://github.com/jedie/DragonPy
DWLOAD server / Dragon-Lib and other stuff: https://github.com/6809
sixxie
Posts: 1129
Joined: Fri Jul 18, 2008 8:36 am
Location: Hertfordshire
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Re: The Dragon Font and lowercase characters

Post by sixxie »

jedie wrote: I think font-6847.png is the Dragon 32 Font, isn't it?
But why are there lowercase characters? Does the ROM of the MC6847 chip really contains the two bottom character lines and the Dragon 32 ROM simply doesn't use it?
Those are invented characters - they're not accessible to the emulated VDG. They're just there in case someone wants a quick tile based font... e.g., the GP32 & NDS interfaces both used that set of characters.
Next Questions: Where are the colored semigraphic charactes stored?
They're not stored, they're generated on the fly.

..ciaran
jedie
Posts: 632
Joined: Wed Aug 14, 2013 12:23 pm
Location: germany
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Re: The Dragon Font and lowercase characters

Post by jedie »

I found https://en.wikipedia.org/wiki/TRS-80_Color_Computer and the related text:
The final significant change in the life of the CoCo 2 was made for the models 26-3134B, 26-3136B, and 26-3127B (16 kB standard, 16 kB extended, and 64 kB extended respectively). Internally this model was redesigned to use the enhanced VDG, the MC6847T1. This enhanced VDG allowed the use of lower case characters and the ability to change the text screen border color. For compatibility reasons neither of these features were used and were not enabled in BASIC, however the resourceful user could enable them by setting certain memory registers.
So, only the t1 VDG has lowercase letters in ROM, isn't it?
sixxie wrote:
Next Questions: Where are the colored semigraphic charactes stored?
They're not stored, they're generated on the fly.
Interesting, i will take a look...
... too many ideas and too little time ... Related stuff written in Python:
Dragon 32 emulator / PyDC - Python Dragon 32 converter: https://github.com/jedie/DragonPy
DWLOAD server / Dragon-Lib and other stuff: https://github.com/6809
jedie
Posts: 632
Joined: Wed Aug 14, 2013 12:23 pm
Location: germany
Contact:

Re: The Dragon Font and lowercase characters

Post by jedie »

I have now add the Block Charachters by hand:
Image

:mrgreen:
... too many ideas and too little time ... Related stuff written in Python:
Dragon 32 emulator / PyDC - Python Dragon 32 converter: https://github.com/jedie/DragonPy
DWLOAD server / Dragon-Lib and other stuff: https://github.com/6809
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