INTRODUCING THE SARUMAN-64... A BETTER WAY TO REPLACE RAM updates and corrections 9-29-2021 One of my least favorite jobs as a repair tech is extracting and replacing RAM chips in a C64, SX64 and Plus/4. If the C64 or Plus/4 board has been damaged by a faulty "brick" power supply or the offending chips are the MT brand which are all known to be bad, I always replace all eight because experience has shown I'll see that computer again sooner or later to replace other RAM that might work fine now but will likely fail as well. An original Commodore C64 or Plus/4 "brick" PS that fails via overvoltage on the 5 volt output can instantly cause one or more RAM chips to short out inside. Those IC's have an absolute maximum rating of 5.5 volts which makes them most vulnerable, and a failing brick can push nearly 12 volts down that line. RAM is the first to be damaged but there might be other failed chips as well. Over the years I've done my share of extracting chips, cleaning the holes and installing sockets for new RAM. It's hateful work which takes several hours to complete, and my cost for the parts alone is over $20. I had taken to swapping out some motherboards and relegating damaged "dead" boards to the shelf to use for parts simply because the standard repair is so time consuming. Also, I have an allergy to solder fumes which makes that work even more unpleasant for me. Enter the SaRuMan-64 a small module sold in Canada by Francois Leveille that is designed to replace all RAM at one time. It's SRAM based and so draws less current than CMOS dynamic RAM chips. These modules can only be used on Commodore 8 bit computer motherboards C64, SX-64, and Plus/4 to replace all existing RAM. They are -not- designed to upgrade earlier computers such as the VIC20, C16 or PET, nor the RAM in an REU. The new components run cool and should therefore outlive the computer. INSTALLATION ON TWO-CHIP (4464) RAM MOTHERBOARDS The SuRuMan-64 module is a "drop-in" replacement for the two 4464 RAM chips in later C64 250466 and 250469 motherboards. No jumpers or other modifications are needed for those boards but of course the original RAM chips must be removed first. It's easiest to just snip all pins, remove the stubs and clean the holes. Sockets are not necessary but can be installed if desired. Earlier boards with eight RAM chips require a different configuration with a few jumpers to complete the install. Note: It's best to mount the module close to the motherboard on boards 250425 and later so the metal shield can be put back. That shield is used in later boards as a heat sink for some of the chips, especially the VIC, PLA and SID. The VIC chip will overheat quickly without it! The latest 250469 short board uses a different family of chips that don't get as hot in use. Still, replacing the shield is a good idea. INSTALLATION ON EIGHT-CHIP (4164) RAM MOTHERBOARDS Rather than trying to extract eight RAM chips intact, the easiest method is to snip all the pins close to the body of the IC's, extract the pin stubs and clean the holes over the area of the module. The first SaRuMan-64 board I installed on a C64 motherboard 250407 only took about 15 minutes to complete the upgrade from snipping out the old chips to wiring in the new board. This requires 21 solder points, 14 of which go directly down from the module to board chip locations (see photo) and the remaining seven connected with short jumper wires. I'll use the 250407 as an example for the installation but it will be similar for the other early C64 boards (326298 and 250425) since their general RAM chip layout is the same. As shown in the photo, the module is placed over IC locations U22 and U23 after all eight original RAM have been extracted or snipped out and the stubs removed. Headers of the new module directly connect all eight address lines, /CAS, /RAS/, /WE, two data lines and +5V VCC. The six remaining data lines to the module are then connected with short jumper wires to the other empty motherboard locations at pins 2 or 14 and the ground connection to the module connected to pin 16 of any of the empty motherboard locations. If you get your SaRuMan-64 module with headers, some of them will have to be cut or broken off if you want to install the module in an 8-RAM C64 board. These include the two headers (2 pin and 3 pin) in the center of the module (flex back and forth to break them), two at the upper right side of the module and one at the upper left side (cut plastic, then break off the pins). See photo. Depending on which C64 board you are upgrading, the remaining header pins may have to be bent inward or outward to match the board holes as each board is different with regards chip spacing. This problem is why I prefer to buy my replacement modules with no header pins, and I solder wires that can more easily be bent to match the board chip spacing, and it allows me to mount the module closer to the mobo. I first solder wires to the motherboard to match the four corners of the module, then solder those to the module after adjusting it's spacing off the board. Then I insert the remaining wires and solder them to the module, then flip the board over and solder them.