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Forum Index : Microcontroller and PC projects : VGA _text_mode_ on pico
| Author | Message | ||||
| robert.rozee Guru  Joined: 31/12/2012 Location: New ZealandPosts: 2442 |
browsing around i happened upon the following: https://opencloudware.com/raspberry-pi-pico-retro-up-with-picovga/ showing the same picture of a pico displaying "Duck on a Pond" in 640x480 VGA that we've all seen before. supposedly just a nice demo, but not much use for anything else... but following the link to the author's website: http://www.breatharian.eu/hw/picovga/index_en.html and the key piece of information in revealed, "ScreenSegmAText(sSegm* segm, const void* data, const void* font, u16 fontheight, const void* pal, int wb) ... Attribute text (GF_ATEXT). In attribute text, each character is a pair of bytes. The first byte is the ASCII value of the character, the second byte is the color attribute. The higher 4 bits of the attribute represent the background color, the lower 4 bits of the attribute represent the foreground color. The colors are translated from a palette table of 16 colors." it looks awfully like this gentleman has figured out how to create a genuine text mode, where the frame buffer is a measly 2 x width x height bytes long. this opens up the opportunity to having a text mode that displays in high resolution on a wide-screen monitor without need for a graphics frame buffer. and with more than 80 columns/24 lines  his VGA library also seems to do mixed graphics and text on different areas of the screen (a la Apple II), but that part looks awfully complicated to drive.he also has a few quite interesting other projects on his website, including a ZX80 work-a-like running on an ATMEGA8 and driving a VGA monitor: http://www.breatharian.eu/hw/atx80/index_en.html with just 1k of RAM, the ATMEGA8 is most definitely displaying the video from a text buffer. cheers, rob :-) Edited 2022-02-08 22:58 by robert.rozee |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7937 |
I like his ZX80 board. Pity the ATmega 8 + crystal + ram chip will probably cost more than a Pico. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 5091 |
The zx81 needs a 168 or 328. PicomiteVGA PETSCII ROBOTS |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4044 |
The 40+MB download put me off!! John |
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