channelmaniac: TIP: Installing a Combo BIOS Parts needed: 1. Colecovision BIOS and No Title Delay BIOS ROM images. These are available on the internet from various ROM download sites. 2. A 27128 EPROM 3. SPDT switch 4. Small gauge stranded wire 5. 2x 220 ohm 1/4 watt resistors The standard BIOS has a 12 second title screen delay before allowing you to select and play a game. This is irritating but someone has created a custom BIOS to get around this problem. This BIOS can be installed by itself or a Combo BIOS using a larger ROM chip that has multiple images of the Colecovision BIOS code can be installed. A switch is used to flip between the versions of code to run to allow the system to run games that aren't compatible with the No Title Delay BIOS. To install a combination BIOS on the Coleco the board has to be modified to support a 2764 EPROM version of the BIOS. Do this first. The code for both versions of the BIOS ROM must be combined into one file. The easiest way to do this is by using the MS-DOS Command Prompt in Windows. (These commands were all tested under Windows XP, your mileage may vary) Rename the files to "OldBIOS.rom" and "NewBIOS.rom" then save the files in the C:\Temp directory. Click Start > Run, type in CMD, and click OK. Switch to the C:\Temp directory by typing: cd c:\temp (In other words, press the Enter key!) Type in DIR and you will see the 2 files in the directory, each with a size of 8,192 To combine them type in: copy OldBIOS.rom /B + NewBIOS.rom /B ComboBIOS.rom Type in DIR and you will see the 2 files in the directory, each with a size of 8,192 AND you'll see the ComboBIOS.rom file with a size of 16,384. Now write that file into a 27128 EPROM with your EPROM programmer, plug it in, and give it a test. With a game cartridge installed it should immedately jump to the select screen. The EPROM has the lower half programmed with the standard BIOS and the upper half programmed with the No Title Delay BIOS. The upper address line on the EPROM is tied high when it is in the socket. This is why the No Title Delay BIOS is being run when the EPROM is inserted. The next step is to wire up a switch to select between the high and low banks. Drill a hole in the rear case of the Colecovision to mount the switch. Be careful on this step! Test fit the switch with the shield to ensure it will fit where you want to locate it. Also ensure you can put the board back! If it's a tight fit you can trim the solder lugs on the switch or trim the RF shield. Fold back the edges on the shield if you cut it to keep the sharp edges from cutting the wires. Remove the 27128 EPROM from its socket and bend pin 26 up enough to stick straight out to the side of the chip. Cut the narrow part of the pin off of the chip then reinsert it into the socket. Run a wire from this pin to the center pin of the SPDT switch. Connect a wire from the upper pin of the switch to ground through a 220 ohm resistor then connect a wire from the lower pin to +5v through the other 220 ohm resistor. Try not to use any existing grounds for other mods such as Audio/Video to avoid noise. The front facing pin C7 is ground, rear facing is +5v and is a good one to use for this mod. Reconnect the system and test. With the switch up the No Title Delay BIOS will run and with it in the down position the regular Colecovision BIOS will run. Congrats! Keep in mind the system may crash if the switch is flipped while power is on. Simply press the reset button to recover.