The only difference between the CTM640 and CTM644 models is the additional 12V power supply for the CPC664/CPC6128's disk drive in the later model.
With the arrival of the CPC664 and CPC6128 models, the existing stock of CTM640 monitors was sold out and later only CTM644 monitors were sold, even with the CPC464. For that reason, the 12V power outlet was designed as a socket for a cable coming from the CPC, while all other connections were made with cables coming from the monitor.
== Technical Specs. ==