Casio Sk-1 with a Video Out

Casio SK-1 Video Out

Gijs of Geiskes.nl has just sent me some information on their recent experiments with patching signals from an Casio SK-1’s ROM chip to a video monitor. The circuit is simply a diode to prevent the back flow of current and a resistor to drop the +5 Volt logic gate to a +2 Volt required for generating a video signal. The color of the pixel is determined by the voltage in between 0 ( Black ) and 2 ( White ), so if multiple points on the ROM chip were mixed with various resistor values color images will occur. Gijs’ result is a series of lines that appear on a monitor in a scrolling fashion. The resulting image is neat and in sync with the sounds generated, however it is out of sync with the screen. The NTSC and PAL video standards require a sync pulse to be sent every so often, without it the image will scroll. Very nice work and I am sure that this technique will work with other circuit bent devices.
Video on of the bend is on YouTube.

Casio SK-1 Video Out Circuit Bent

11 thoughts on “Casio Sk-1 with a Video Out”

  1. Interesting. He’s sending the data lines to video? But, the logic pulses are all just on/off voltage, so each one would only give you one color? In order to get multiple colors, you’d need to use multiple data lines with different resistors? What would be needed to sync the screen?

  2. A microcontrollier like PIC can be used to generate the sync signals and buffer the data outputs. There are some analog ICs that I believe will also do the same thing without all the nasty programming.

  3. In gijs’ case, i think the time base corrector inside the panasonic ave-7 does the trick. I recently made a small info page on cheap video mixers with inside tbc. maybe useful when you like to try this with a video projecotr: http://www.karlklomp.nl/inf/faq.html

  4. ladies anf gentlmen i just stumbled on to this site!!

    am i hearing this right the SK-1 sampling keybourd had video output? of some kind ?

    Now i know for sure that one of the older Vantage (1995) Roland Sampling keyboard Workstations had a 9 pin D-SUB connecter that carried RGB Video witha 15.7khz Horizontal / 60 hz vertical out timing that was suitible for the atari ST 103 Monitor and some others & Composite monitors.

    but am i to understand that the SK-1 had some sort of similare Video output with some sort of Gui?

    or was this just a digital out put artsy farty kinda thing to display some quazi artistic digital noise on a screen.

  5. cool well i did somthing very simialer in 1982 with malfuntioning motorola 6802 based GDC 1200 bps modem that wqas going flaky. By using the 8 data lines of the 6802 to form a passive randm cpu noise maker. the R2/R ladder was used to form a binary waited 8bit 256 step D/A wavform used to generate “bizzar random sound crashed CPU” noises” fed to an audio amp for noise & video display for ohh lala while the Random d/a wavform would randomly cuase the cpu to reset thus restarting the rcpu for random..

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