Certain considerations about the Bluetooth connection of the light pen also apply. GW-BASIC allows use of joystick and light pen input devices. The XG-1 is a specialized light pen. This contains the VCOUNT value captured when the light pen/light gun trigger is pressed. Sample waveforms could be displayed on-screen and modified using a light pen. The PCjr also has a light pen port. The user drew on the screen with the recently invented light pen. The 6845 had support for a light pen, an alternative to a computer mouse. The Vectrex light pen was invented by John Ross. A light pen was also available with the system. Contestants write their wagers using a light pen on an electronic display on their lectern. The light pen itself had a small photoelectric cell in its tip. This contains the horizontal color clock position when the light pen/light gun trigger is pressed. For the MSX computers, Sanyo produced a light pen interface cartridge. A light pen can also allow users draw on the screen with great positional accuracy.