THE JETCO automatic teller machines (ATM) are an ubiquitous sight in Hongkong. Most people know that ATMs provide instant and easy access to their bank accounts. But few can have a clear idea of how JETCO does this in a matter of seconds. A quick look at JETCO reveals a special organisation which provides a high quality of service for account holders of 40 banks across Hongkong. About 10 years ago, five banks banded together to form the Joint Electronic Teller Services, or JETCO. The idea was to provide a few simple, but vital, services to account holders. These included withdrawal of cash, balance enquiry and transfer of cash between different accounts within the same bank. The success of JETCO in providing these simple services meant that it became increasingly popular, with more and more banks joining the fold. There are now more than 1,000 JETCO terminals. Project manager Ms Stella Cheung said: ''We are basically a switching centre for messages between member banks. ''Our member banks use different machines. While most of them use IBM machines, they also use NCR and other UNIX-based systems.'' To provide the link-up between different banks, the front-end processors used different protocols. JETCO used three kinds of protocols to link up member banks. SNA/LU6.2 provided peer-to-peer connection between JETCO and IBM and its compatibles. Bisync 2780 linked up those banks using NCR machines. ''And, finally, we also use the standard X.25 for the rest,'' Ms Cheung said. There were different levels of protocol between the host banks and their terminals, but these did not concern JETCO. The teller service company came into play only when JETCO card holders used ATMs of other member banks to gain access into their own accounts. Since all the ATMs were owned and run by the different host banks, these terminals were directly connected to the host bank's computers. ''If you have an account with, say Standard Chartered Bank, all the information relating to that is stored in Standard Chartered Bank's files,'' said Ms Cheung. ''So, if you try to access your account using the JETCO terminal at say, Chekiang First Bank, then the terminal will identify your card as our network card, accept it and then forward the transaction to Chekiang's host computer. ''The host computer will identify that the card is not issued by Chekiang and will accordinglgy route the transaction to JETCO, which, in turn, will forward the same to Standard Chartered Bank. ''Now, the host computer at Standard Chartered will check your files and - if you are trying to withdraw money from your account and you have enough balance - it will authorise the transaction and then update your file.'' Standard Chartered would then send a transaction authorisation to JETCO, which would forward the same response via the Chekiang host to its ATM terminal, she said. Ms Cheung added: ''A normal transaction will take less than two seconds for transmission of a request through JETCO and back.'' FACTFILE NAME OF ORGANISATION: Joint Electronic Teller Services (JETCO). NUMBER OF EMPLOYEES: 36 TYPE OF BUSINESS: Computerised banking service. HARDWARE: TANDEM Cyclone with five CPU, 160MB memory, 23.9 GB disk space. TANDEM CLX with four CPU, 64MB memory, 6.48 GBdisk space. SOFTWARE: In-house developed application software.