Check the listing for details. RAINBOW TOS 1.4 Atari ST/STF/STFM & Mega ST NEW 6 Chip EPROM. Listed at 49.95 USD. Rainbow TOS 1.4 for Atari ST/STF/STFM & Mega ST computers. New in 6 chip version. Note : 2 chip versions available on request or on Ebay: Rainbow TOS 1.4 Atari ST/STF/STFM & Mega ST New 2 Chip http://www.ebay.com/itm/140953378159 Picture is of a typical set. We have some sets from Atari that have different labels and or chip types that are from different production runs. No soldering required if you replace with the same version(2 chip or 6 chip that your old TOS is). Picture shows both sets but this auction is for the 6 chip set only. You can get the 2 chip by requesting it. The installation instructions are provided at links below. You can switch from 2 to 6 or 6 to 2 by changing the solder jumpers and installing sockets IF they were not installed originally. Read Instructions and check your ST. Take computer apart, remove old TOS, insert new TOS and just put it back together. Many improvements and bug fixes. Sorry Atari was no very consistent about where they put the chips or how they were orientated. Only requires phillips screw driver, needle nose pliers plus a tool to remove the old TOS(I use a flat blade screwdriver). Open and check your computer TOS set and let us know which set you need(2 chip or 6 chip). Shipping weight is estimated to be 1 pounds. Click here to review my terms & conditions. "If you do not understand something about an auction then PLEASE contact us and get an answer you understand before purchasing. EBAY NOW CHARGES FEES ON SHIPPING AND HANDLING. WHEN YOU BUY MULTIPLE ITEMS AND PAY BEFORE WE SEND A COMBINED INVOICE YOU MAY PAY A LOT OF EXTRA SHIPPING."