You should definitely do more things like this with how programming works

This brings back a lot of memories. It was like 2000 or 2001 and I was learning C using books and a compiler written in the 80s! (Borland Turbo C/C++ 1.1) I still have a great sense of nostalgia for that blue background with chunky yellow text and seeing functions written in that glorious font with pointers that poke and peek directly into memory and occasionally prodding hardware registers brings back some fond memories. Thanks , Dave!

Your fluency with bit-shifting and boolean is mesmerizing; a master-class video from you would be solid gold.

Greetings from San Francisco. I thought there were no time machines, but you just brought me back to 1979. I loved it the first time around, and I'm (almost) ready to break out my Poly88 with a Cromemco Dazzler and write code along with you. Almost... but sanity prevailed. Dave, you are a BAD influence. I can't wait for your next stroll through my faded youth.

I remember implementing the Bresenham circle algorithm in assembly and also figuring out the math behind it when I was in 8th or 9th grade where I had just learnt the the Pythagorean theorem. It was so awesome :)

Loved this! Man, this takes me back. I still prefer to program in C (not C++) to this day, usually using a GNU compiler which supports the newer versions of C. I remember programming graphics in DOS on my old computer in the 1990s. I wrote my own graphics library much like you have here by accessing A000 etc... as I learned I added more functions to it for lines, some optimized functions for straight lines (I think that used memset commands to set larger amounts at once). I loved those days and the fact that it wasn't done for you. I created a free game called Deluxe Pacman 1 & 2 for DOS, older Windows and modern Windows (last tested on Windows 10) and it is coded entirely using C (no plusses), only it uses the Allegro library (I honestly wish I had done it entirely on my own and never used a library). Good times anyhow. Oh, and I used to use DJGPP for DOS back then, it handled the memory limitations for you, so no worries about things like long jumps and the like. I believe Quake was written with it. Very nice.

You can speed up that Bresenham's implementation considerably by avoiding calls to SETPIXEL. Instead, translate the x,y starting point to a byte address and a mask (as done within SETPIXEL), and within the loop, treat x moves as shifts of that mask (adding/subtracting one to the byte offset if the mask becomes 0), and treat y moves as adjustments (add/subtract BYTESPERROW) of the byte address. Back in the day (circa 1985 with an EGA/VGA adapter on a PC running MS-DOS) I had an assembly language Bresenham's that was nearly as fast as a NEC 7220 based board. Also, for a lot of applications (I was doing CAD work at the time), it is well worth the minimal effort to optimize horizontal and vertical lines.

More C programming please. Love it!

This reminds me so much of when I was a kid programming different early machines that did not have any built in graphics like the early Atari and TRS80. I love it, please make more videos like this one. Thank you very much.

That was awesome! I remember doing this in the early 80's. I have a lot of nostalgia for this and sometimes actually miss it, if you can believe that! More please!

A few years ago I wrote a graphics primitive library for Arduino driving a 20*10RGB led array. This was used in a series of digital art workshops as part of our National Arts Festival. The best of the art was later displayed on our huge Rgb periodic table display. Each element was about 6x6” . Since the pixels were wired in an odd order I created a translation table to translate x/y to pixel number. Fun times.

Dave, enjoy your podcast. Would like to see you interview the folks who made up the team that created the 6502.

Great video!! I never have to touch low-level programming in my line of work but as time goes on in deepening my appreciation for this technology and the people who both understand it and are willing to share it. Everything is built on top of this! Incredible!

This is amazing! It also shows up how in previous a programmer have to think twice before using a single byte otherwise they may run out of volatile memory. The code was clean and explanation wad on point. Really great work!

Thanks Dave, it really is quite nice to receive a master lesson on such simple graphics outputs. Reminds me of learning Fortran over a night shift so that I could modify a shift trivia quiz to include a graphical image, using ascii characters. Amazing what you learn when you need it! Writing Trev wins with an image of a winners cup, no matter who wins, was the result I famously added to the code! Take that A-shift! Hahaha 🤣

Happy memories of designing a tiny antialiased font to draw text in 256 color SuperVGA. It was for a simple GUI to acquire and show CCD camera data for use in an electrophysiology lab (looking at calcium transients in cells using calcium-sensitive fluorescent dye). Somehow there was enough room on the screen to display the image frame, a histogram and a control panel at the same time. The advantage of whatever mode I used was it had square pixels (so the image frame wasn't distorted) and there were enough colors to represent the range of intensity values coming in from the camera. If I remember right, it was a variable width font with maximum width 6 pixels and a height of 9 pixels. The manual 'antialiasing' was two-tone.

Hi Dave, thanks for the great video! This takes me back to my C64 days. You're absolutely right about the bit pattern for the characters being right to left on a left to right ordered screen memory. Though I never even gave it a second thought at the time, it just made sense since it was writing a byte to memory and that's the order of the bits for a 6502/6510

Ah brings back memories getting into assembly on my 6502 atari 800 xl back in 1981 or something... Still up till this day, 40 years later one of the most satisfying periods in my life :P

Really love this Dave! It's so great to draw some wisdom from the older generation of programmers. I'm continually amazed at the kind of fundamentals you develop if you don't spend all your day debugging yaml templating

You're my hero 💙 and all I have been looking for. Finally now I have a tutorial guide for the idea behind how graphics were designed and implemented.

This is great. I recently wrote my own graphics API using similar algorithms. I will have to add Moire! Thank you for your channel.

I'm glad that i took hard copy of my gfx library back in mid 90's. After HDD crash it would have been gone otherwise. "beautiful" C and assembler code in actual paper made by bit over twenty years old Airjuri. :D It has filled polygon, bresenham line, -circle and some screen fading effects. Off course all optimized for 320x200 screen. I should probably finish that game project i started back then ;)

Great video, it's always great to take a stroll through low level land and look under the hood. We take a lot of modern libraries for granted!

I'm surprised how simple this code looks, despite the fact that it's so low-level. Very interesting!

This C stuff is so great to watch it was a simpler time, but at the same time more complicated (?)

I'm learning Spring Boot and Java, a real programming language as many people say, not like JavaScript. I found out Java was based on C. So many things worked thanks to C, it's incredible. I also just found out your channel, it looks very interesting. Keep it up. 👏👏👏

I love the fact that you are probably going to be the only human on this planet running this code, but you still have sanity checks to ensure that you're not going outside of screen memory. The force of habit from a person who has had to reflexively sanitize inputs his entire life.

I’ll absolutely take more of this. I’d like to see code for capturing mouse and keyboard input.

I’m a beginner but still so interested in low level programming. This is amazing! I feel like C is such an awesome first language

It brings me back to the good old days when the bar was low regarding customer expectations, and it was easy to impress people. Even yourself.

Dave, this was super-cool! Thank you so much for posting this video. Yes, would love to see more content like this. Cheers!

I used to love creating my own character graphics on bbc basic. I’d have loads of 8x8 graph paper doodles then calculate the byte for each line. I was 8.

I remember doing this kind of programming for the PC before windows came out. Sound drivers too… fun times. Blew up a monitor or two.

As someone with little programming knowledge this video is really good.

Yes, I remember my first challenger in programming when I was teenager and was to create a line function, no internet, no books. Then next challenger was a painting function, seriously very complex for me and more easy was to create a draw circle or ellipse function, only play with sines and cosines.

Taking in stuff that's over your head is the first step to raising your head so time well spent.

I started using C for direct screen graphics in the DOS days using interrupt 10 to set VESA video modes. There day I still enjoy writing directly to the screen using C++ and the frame buffer and more recently drm/kms on Linux.

Excellent. Please continue professor...

It's cool because I always knew how font code in terminals technically works and probably could write it myself but its just cool to see it. I never really knew where that code actually exists in Linux whether it's a library function or something in BASH. It's such a basic thing to draw ascii it just feels like one of those things that's so rudimentary yet important that i don't even know where to find it

That takes me back to programming on a VGA in assembler. I remember wishing I could do it in C.

That display is beautiful. I love old graphics

I gave this a thumbs up before I even skipped past the ad that preceded it Edit; And after watching, I wasn't wrong.

Really enjoyed this one. I am somewhat in the middle of working out how to render text to the C64 bitmap display, so this was a handy video.

Assembler gets my vote :) Thank you, Dave!

Hey Dave, Very cool! Love the KIM-1 drawing some cool stuff. Some ideas for next videos: - Since you now have the Commodore start screen, implement BASIC 🙂 - Let it draw the Mandelbrot set 🙂 - Port a C64 game to the KIM-1. Probably an "easy" one, without sprites... OR, implement you own game... e.g. Tetris 🙂 Keep up the cool videos, especially about Commodore stuff and the KIM-1. Greetings from Germany, Nils

Thank you sir. You are a living library.

Sounds like the beginning of a C only/CPU only 3d renderer from scratch series :)

Hi. Great video. Every video I've ever seen you make is a great video. I wrote a line-draw algorithm using Bresnahan's algorithm, which is faster than the most modern line-drawing algorithm. I used system functions to draw text. I might rewrite that to make the text code more portable. At 3:22, you said the 127 was for the leftmost pixel and 1 was the rightmost pixel. I think you meant 128 and 1, unless the pixel is set to zero, in which case a mask of 127 is correct for the left-most pixel, and a mask of 254 is needed for the rightmost pixel. I'm sure you know what, and that most people realized what you meant.

Please make MORE of videos like this.

That reminds me of the first games I tried to make in high school. Going from amiga to a PC, playing with power basic and int 13h screen modes. How you could swap between 2 screen buffers to not see the screen flicker during updates. It was cool how drawing triangles, and fill routines worked. Reading code from dr.dobbs journal in asm.

Would love to see you make a program or game for the Commander x16. I've programmed C for 3-4 years, and I struggled to grasp this from the first second. If that is basic, I bow to your skills.

Nice idea of porting a C compiler, even if limited, to the KIM-1. Good stuff.

FINALLY someone who gets my goals c:

I am a big fan of your channel. Not much of a programmer, I hope you can one day start an x86 assembly tutorial for some of us who learn best by watching. It would be nice to see some practical x86 tutorials and its relevance to old hardware. I have some books but theory is not the same as practical.

Dave, would you be willing to do a programming series? I'm talking about all programming languages, from the ground up, at least the basics. I need that, and I'd bet others do too. You explain things better than most.

Hi dave, I made my own petscii font (C64) in python with hex codes in a list. I used it for the LED Matrix TEXT scroller I built from a leftover 2812b strip. It was fun to do.

You're very talented. This video is great

Thanks for the memories.

excellent, expect more things like this, thank you

3:22 *Correction:* 128 is the first left pixel. 127 would be the right 7 pixels of the first 8 pixels. The Apple 2 reverses the bits for HGR. LSB is left-most bit, MSB is a palette bit, and bit 6 is the right-most pixel.

Thank you Pal!!!! ESPECIALLY Thank you for Windows 95b OSR2 - my first "my" PC my dad bought me was a 133MHz Pentium w/MMX inside Packard Bell, i wish i still had it. I remember finding out that the Right-Mouse button did stuff 0.0 and then as i explore every little piece i could, i would check out the About... and find your name many times. before that my computers were the tandy color computer line, i remember creating my own operating system/client-user-interface/data-decoding-REencoder using an interfacer with my coco3 and two half height floppy drives. course at the time i didnt know any of those words, i was just trying to create a master program i could have perform multiple computation tasks while i was at school and then review the results on disk when i got home from time to time. but i was like 12 or something, soo... You though, you totally rock man!!! I love your videos and show them to people i know in my local area including a friend a few days about about your book, he told me he's going to check it out. and for the on-topic subject: yes i love your videos, every chance i get some free time, im checking them out. i especially love your style of C/C++ which is gnarly awesome!! I am in the process of working on my own (is it 'retro' the kids calling it these days??) anywho, my own 'computer' of sorts from scratch. I am hopeful i can get something that i can eventually mass produce and sell but we'll see

It would be interesting to see how LLVM-MOS compares to CC65 these days. There are some rather large projects using LLVM-MOS now, including CP/M for the 6502.

Love you explanations, so easy to understand.

Mode 0x13 Oh this bring back the good ole tutorials

Loved it... Just the episode for "weirdos" like me that think doing stuff like a console graphics library, console raycasting renderers and the like is "fun". A graphics "first principles" of sorts. If i may suggest, add a text renderer that won't wrap and only draws whatever is within the valid screen area. Scrolling text, floating text, moving text in general. Guess FloodFill is next :P

Will we ever see a new Tempest bath robe record run again? Loved the last record video and the atmosphere where you had a casual morning with your coffee and setting a new record. Highly enjoyed watching it during my morning routine as well. :)

Really great. thanks for the insight.

Nice tutorial short & to the point.

Why not reorder the ramfont instead of using translation tables for finding the right index?

When a grid misaligns with one that's behind, that's a Moire!

This reminds me times when I was seven years old with zx spectrum at home, some programs in basic and one book to look at and to learn from. For some reason my mother which knew something about programming (algol, prolog ,fortran ... not sure) from university helped me with writing programs drawing doilies. I guess it was some cycloids with use of trigonometric functions. But I'm sure basic had sin, cos, putpixel or similar command. It was nice to watch cause it took some time. I'm surprised that computer from that era has C.

With SVGA graphics, the SetPixel function must obviously be tweaked for what colour the pixel should be; obviously an int type will do, but care must be taken to ensure the proper ordering of alpha, blue, green, and red channels. And now I also know how my own homebrew library, for rendering NURBS contours, should be written.

You could save 256+ bytes from result just rearranging of font array. And even save some ticks of CPU. Precalculatable things should be precalculated.

Awesome explained

Man, it's been many decades since I've seen code this far down in the weeds, but I do remember the good old bit flipping days of C/ASM. Thanks for refreshing those brain (RAM) cells... should be good for another 30 years or I get unplugged.

This is so beautiful

I'm doing the same thing today, on MCU ;p (started on Apple 2 in 81, 8Bits, Official Atari dev, Next, BeOS, Mac, PC, Dreamcast, GC, Wii, PSP, PS2 3 4 5, Xbox etc.. And now back to the roots on MCU, and back to 2D, Threads, Memory, Filesystem, bootstrap and void main(void) ;p

Actually, adding another comment has become my trade mark. So I would add that we should explore the layers of programming onions to see if we can create a screen function, similar to screen 1,1; or screen 2 altering the mode to graphics mode, just like the PET. Be interested to see if you could add this to the simple graphics card in some fashion! 😊

I think I would have needed 3x more lines. Great job.

I’ve always had this misunderstanding of how to use bit shifting and utilizing bitwise operands, a video on that would be very nice !

I did almost the same thing about 20 years ago on an 80286 PC. As I remember very clear about the address 0xa000. It is the begining address of 13h VGA mode, which is a 320 x 200 screen. After Microsoft Windows 95, you can't draw graphics by writing data to screen memory.

Could you show how cpu instructions set implement to programing language and vice versa?

Takes me wayyyy back to the 80s/90s when I was teaching myself graphics programming. Turned out it was a passing phase and sysadmin/programming then database work was where my future lay, but fun nonetheless.

I once had to do something similar in TRS-80 basic to render a working analog clock. The "pixel" drawing was quite interesting in that machine since the character set contained 64 characters consisting of 2x3 black&white (black&green) blocks (one character for each possible combination of those 6 "pixels"). The way of walking a line to draw each pixel was pretty much the same as in your case, Dave. The "mathematics" (missing most of the C bit manipulation options) of setting/clearing specific pixels was a bit of brain teaser though. And needles to say that it was slow enough to make a real-time seconds hand unthinkable. On the other hand, clearing/filling the screen (when done in machine code) was fast enough to create a stroboscope thanks to the mere 1K of video memory and the mighty handy LDIR or LDDR instructions (those of you with any Z80 experience can probably code that in under a minute). Anyway, thanks for an entertaining trip back in time to those early times where problems had to be solved by pure brain-power rather than processor-power. :)

Very nice. Always interesting to see how tasks like this get done with different languages. I'm currently working on a collaboration for a game engine written in Windows Batch. It's amazing what the language is capable of when you know how to use it to full effect.

Bring almost bare-bone to live never tires me, that's why I became a BIOS engineer, so much fun.

Very nice!

Really neat stuff. Not as low level but I remember doing the turtle graphics in Pascal. There was a lot of advanced stuff with assembly I found from a really talented Dutch programmer I had befriended at that time that did really remarkable stuff with animation and fonts and all sorts of stuff I wish I kept. I’m sure it’s on a random 3½” floppy in a box at my parents house that if exists probably wouldn’t work it is virus-laden.

Hi Dave … would you consider to create an Assembler and C-Language Beginner tutorial series? I know there are a lot of tutorials here on YT, but not in that type of quality 👌🏻

I would love to see this on each of the current major platforms too, because this is how I started coding on every machine: Apple II, TRS-80 Model 1, ZX Spectrum, Amiga, DOS & older Windows. Usually first in the native BASIC and then moving to machine code, assembly, C, C++. But on modern Windows, Mac, Linux (and maybe the phone OSes) I would love to do the same, but man it's hard to impossible to find some example or tutorial like: - Use the "native" language of the device/OS: C, C++, C#, Swift, Kotlin - Don't use any frameworks or libraries or SDKs other than the most basic ones the OS comes with or its official community/free dev tools come with - Use the lowest level supported techniques of the device/OS - Open a window, or preferably a screen or a full-screen borderless window - Be able to draw either by some equivalent lowest level graphics primitives equivalent to plot() and line() - OR to have access to bitmap memory where I'd need to implement my own plot() and line() primitives - Handle window resizing, screen resolution changes, etc (in other words no hardcoded window dimensions) I realize most and probably all systems now go through a 3D pipeline even for 2D graphics and may not offer any direct way to the native hardware bitmap since that belongs to the graphics card. But a full and thorough discussion of this would be one of the major parts of the basic intro at the start. Then old fart programmers could have fun like the old days on their fast new systems! Someone start a git repo (-:

Dave you are a badass.

look at this fancy guy with his framebuffer for doing bitmap graphics. Not even having to make a pretend one with character memory.

Really nice👍

Good stuff. There is a DirectBitmap class on stack overflow that'll give you C# for drawing pixels at speed in winforms using a pinned memory array. What graphics functions could leverage parallelized linq? That's probably an unexplored niche.

This is my morning drug

Brings back happy memories of coding on a DOS box and having to implement all of that functionality myself. How quickly could it render to a screen buffer and then flip it to the display? Or is there not enough main memory for a buffer?

Hey I just started learning C yesterday!

Hi, Dave. nice c video. do you have some videos about your IDE and plugins/extensions you used in the video? nice piece eye catching is the mouse-over tooltip showing variables/functions call info. that's nice to have

jurassic park Dave, rock on!

Could also use xxd -i to generate the font array.