Quest used a serial network based on RS485. The Quest ECM50 was an intelligent controller that used ethernet to communicate with the Point of Sale host PC and RS485 (Questnet) to a network of Quest Terminals. I was responsible for the design and release to manufacturing of the ECM design and also writing and maintaining the Firmware it contained. The ECM design was very clever as the code development could take place on any production ECM and then be recompiled for ROM and downloaded via ethernet making development quick and easy.
