From C64 DTV Hacking Wiki
 Getting started
 Quick test
If you just want to have a quick look without any hardware modifications, you can go to a BASIC prompt using the built-in easter egg:
- In the blue "READY." screen wiggle the joystick left-right or up-down very quickly.
- Then, LOAD"$",8 instead of LOAD"*",8,1 will be run, giving a list of programs that can be run using the joystick, most notably the BASIC Prompt which features a keyboard emulation that can be accessed with the joystick.
 Connecting the DTV to the outside world
To get data on the DTV, you need to add at least :
- a keyboard port (see keyboard mod)
- a joystick connector OR a floppy/IEC connector (see joystick mod/floppy mod)
 Power supply
Make sure the keyboard gets 4.5 to 5 Volts DC. 6 Volts (4x1.5 Volts normal batteries) will probably fry it!
- Use a regulated/stabilized 5V DC power supply, 500mA or more
- USB chargers and some mobile phone chargers should be okay.
- Or rechargeable batteries (4x1.2V)
- Or a standard/non-regulated power supply (12V,...) with a extra regulator to 5V. Add a 1N4148 protection diode pointing from pin 3 to pin 1 (see here (German) why)
The DTV board is designed to work with a 3.3V voltage. The built-in red power LED works as voltage reference in the DTV's 3.3V regulator circuit - so don't remove or replace it with a different LED type (1.8V forward voltage needed - especially blue LEDs are not suitable). Replacing this regulation circuit with a linear regulator is possible but seems to reduce power consumption only by about 15% (from ~166mA to ~140mA - PETSCII forum thread).
The DTV power switch wiring is a bit unusual. It connects DTV ground ("E-") to battery ground in "On" position. In "Off" position, it connects the 3.3V DTV line to DTV ground via a 100 Ohms resistor ("Dis"), probably to discharge capacitors. Keep this in mind when attaching peripherals whose ground connection might bypass the power switch.
 Transferring data to the DTV
 DTV Hardware Mods
please add only 'best' links here - this is not intended as a 'complete' link collection
- Simple colorfix for DTV2/PAL. In a nutshell: Add three 220Ω SMD resistors (0603 packaging; 0805 also fits) in parallel to the existing R16, R20, and R24. Also, add one 330Ω resistor (a standard wired one works) from the point between R14 and R16 (the side of R16 pointing away from R20 is okay) to ground. Use a grounding point a bit away from the audio line to prevent noise. 166Ω can be measured on each of the additional resistors if soldering is okay. Reported to work even better than the 'true' colorfix as suggested by Mr. Latchup which requires replacement of 17 (!) SMD resistors. Good SMD soldering skills and equipment needed! Comparison of palettes. Note that for perfect colors the software palette needs to be changed, too (DTVSlimIntro can do this).
- S-Video output for clearer video (for Hummer. Remove C10 for DTV2)
- DTV2 PCB boards: Keyboard/Floppy/Joystick/Video/Audio/Userport solder points picture. If you want to change the casing: bottom side solder points are more accessible.
- Make sure you patch the kernal with kernal patcher before doing the userport mod since the standard kernal sets PAL/NTSC mode depending on the userport's wiring.
- Joystick connector pinout: JoyX0=Up=Pin1, JoyX1=Down=Pin2, JoyX2=Left=Pin3, JoyX3=Right=Pin4, JoyX4=Fire=Pin6, Gnd=Pin8, +5V=~Bat+=Pin7
- Bat+ is the batteries' positive pin so it's about 6 Volts with normal batteries (too much for a keyboard!) and about 4,8 Volts with rechargeable batteries
- IEC/PS2/S-Video/Joystick pinout
 Case Mods
- DTV64 Micro Tower: Case mod, with all the trimmings.
- DTV Keyboard Console: A slim keyboard casemod.
- Picodore 64: Miniature DTV laptop
- Various case mods
- Expansion bus mod
- DTV Yellow Box: DTV in a Box
 Additional hardware
- PS2 Mouse on the DTV: Adding a PS/2 Mouse to the DTV
also see Peripherals and Add-ons