Subject: UPGRADE: Ramdisk LED
Author:  Guy Ferrante

                         The RAM-Disk LED Mod vl.0
                           by Guy Ferrante  1994


In 1989 I got my first MIO and was thrilled with all the power this box
had. One thing which caught my fancy was the LED. It was cool to see it
blink while accessing the Ramdisk. I decided to incorporate this feature
with my internal ramdisk and developed this mod.

This mod is for Atari 8bit computers with memory upgrades like the Rambo or
Newell 256k-4meg upgrades and may also work with XE types as well. This
upgrade should be done by users that know how to solder, read schematics,

Parts List:

 Quantity         Description
    1    510-ohm 5% 1/4 watt resistor
   20"            hookup wire
    1          LED (any colour)
    4        1" heat-shrink tubing

You can get all the parts at your local Radio Shack for a dollar or two.


   * Decide where you would like to mount a LED on your computer. I have
     mine right above the RESET under the clear plastic strip. Be creative!
     You will drill a hole somewhere so plan carefully.
   * Open your computer and locate the PIA - it's marked U23 in the 800xl.
     Now solder one end of the 510 ohm resistor to PIA pin 14. You may want
     to clip the resistor leg a bit so you can bend it over the PIA.
   * Cut the hookup wire in half.
   * Solder one wire from the 510 ohm to the short leg on the LED.
   * Solder another wire from the long leg of the LED to the right side of
     L25 - a Green resistor-like thing. This is 5-volts for power.
   * Now mount the LED!
   * Use the 4 pieces of shrink tubing on the resistor legs and LED legs.
     It should look like this :

      _ _
     | U |
     |   |
     |   |
 pin |   |                      LED
 14 -|---------------/\/\/------> <------  to 5V (L25)
     |   |          510-ohm
     |PIA|          resistor
     |   |

Now whenever you access your ramdisk this LED will blink like the LED on
your 1050 or Hard drive!

I would like feedback on this mod. Tell me where you mounted the LED. Did
you find a better 5-volt location than L25?

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Acknowledgements: My thanks to James King for providing this document for
Disclaimer: The contents of this document are Copyright  by the author.
This HTML presentation is Copyright  1995 by Michael Jewison. Any
rebroadcast or retransmission without the express written consent of
Michael Jewison and the Canwest Global Network is strictly prohibited.
This information is being presented for informational purposes only.
Neither the author nor the administrators of this site can be held
accountable for damage to your equipment as a result of installing this
Last updated: October 12, 1995
Comments are always welcome. Send them to

Craig Lisowski (