Back to Table of Contents 4.8 WHAT ARE THE DIFFERENCES BETWEEN THE 2-PORT AND 4-PORT MODELS? The 4-joystick-port model comes with an automated RF switch box that is not found in the 2-port machine. The 4-port unit has a unique power setup. The power supply plugs into the TV switchbox and the TV wire from the 5200 carries power to the system from the switchbox while also providing the video display to the TV. In addition, most 4-port 5200 systems cannot use the VCS cartridge adapter without modifications. Several other minor differences also exist between the two machines. -- (Taken from ANALOG Magazine) Later releases of the 5200 incorporate some minor hardware changes. Controller ports 3 and 4 have been eliminated, making POT7, TRIG2, TRIG3, and bit 1 of CONSOL useless. A few of the connector pins have been redefined. Pin 2 of the I/O expansion connector now carries POKEY's Audio Out signal. Three pins on the cartridge connector have changed to accommodate the new 2600 adapter. The system clock, 02, is output on pin 14, isolated through a diode. An alternate video input is taken from pin 24 and is also isolated through a diode. Pin 30 provides an alternate audio input. There is space on the newer boards for circuitry for a PAL (European TV standard) version of the 5200. Also, on power-up, the monitor program checks for the PAL version by examining the GTIA register PAL after step 2 of the initialization routine. It also checks the cartridge program for PAL compatibility. The byte at $BFE7 should read $02 if compatible, or $00 if not. This is the only important change to the monitor program. There are some additional hardware changes, but none affects the machine's operation from the programmer's view. Back to Table of Contents