Building a pixel-perfect C64 terminal emulator required research into the VIC-II chip's specifications and accurate color reproduction.
The Commodore 64, released in 1982, was one of the most popular home computers of all time. To create an authentic terminal emulator, we needed to match two critical specifications: the exact screen dimensions and the scientifically accurate color palette.
The C64's VIC-II video chip displayed text in a fixed grid of 40 columns by 25 rows, with each character occupying an 8×8 pixel block. This gave a total screen resolution of 320×200 pixels.
Implementation: We use CSS calc() to dynamically scale the font size
based on viewport width, ensuring exactly 40 characters fit across the screen:
/* Calculate font size for 40-column display */
font-size: calc((100vw - padding) / (40 * 0.6));
/* 0.6 = monospace character width-to-height ratio */The C64's color palette has been a subject of debate for decades. The VIC-II chip output colors in YUV color space for PAL/NTSC television systems, and converting this to RGB for modern displays is not straightforward.
The most scientifically accurate palette is the Pepto palette, created by Philip "Pepto" Timmermann through detailed analysis of the VIC-II chip's color generation, including proper gamma correction for modern displays.
Our C64 terminal uses the classic blue background (#352879) with light blue text
(#6C5EB5), matching the default C64 boot screen that millions of users remember.
Additional visual authenticity comes from proper line spacing, matching the original boot sequence text, and implementing the characteristic C64 cursor as a solid block.
Pepto's C64 Color Analysis
Comprehensive article on calculating the VIC-II color palette with gamma correction.
C64-Wiki: Color
Documentation of the Commodore 64's 16-color palette.
C64-Wiki: Standard Character Mode
Technical details on the 40×25 character display mode.