there's four / five basic systems:
(1) wait staff "memorizes" the order table side, orally relays to the kitchen. works for small, not so good for big.
(2) wait staff takes/writes the order(s) tableside, then rips out the 'paper ticket' and hands off the paper ticket to the kitchen
(3) wait staff takes/writes the order(s) tableside, then goes to a 'station' and 'enters' the order(s)
(4) waitstaff has a wireless device, takes the order(s) table side, hits "Enter" - all done. no paper except for billing/receipt issues.
and exceptionally more limited use:
(5) "self-serve" order entry. pick a table, sit down, customers punches in their own order. dishes mystically appear from the kitchen delivered by someone they've never seen before. there is no service / wait staff, only 'delivery staff.' not suited for much past fast food "no options" other than one-from-Column-A-and-one-from-Column-B.
>>Do I understand correctly?
no. it is the difference between system 3 and system 4.
"old style" system 3 used mouse & keyboard, "new style" system 3 is touch screen - and how to enter "special instructions" is a thorny issue there.
system 4 totally bypasses the "go to station and enter order(s)" thing. instead of writing up a paper ticket / document to use / 're-enter' at a 'station' the information is directly entered real-time at the table. obviously needs to be a secured wireless network, otherwise the hackers will be ordering up triple thick, ultra rare, stegosauous steaks for table 4 - which is suddenly discovered to be empty.
>>Actually, I have seen in many restaurants (as a customer), that they don't use tablets for menu. My idea is to display the menu to the customers on a tablet (comes with pretty good advantages, but at a cost). But, I don't want to replace any existing hardwares/softwares of the system used by the restaurant. That is what I meant by saying I need to compliment the existing ordering system.
what I read this is simply moving away from a paper menu to an electronic menu presentation.
for a 20 table establishment, and a $200 electronic menu tablet, that's $4000 in capital investment, or more - one 'tablet' per table or per customer?
vs. $0.03-0.04 per laser printed daily menu. do the math, four cents per paper menu vs $200 per tablet per customer - takes 5000 customers to pay off. presuming no tablets break or get stolen.
it is simply not possible to go any further than 'electronic menu' vs 'paper menu' without replacing/expanding hardware/software already in use.
and in fact, the most rudimentary "menu tablet" will required daily / hourly / on-change 'up-dating' to avoid the customer seeing / being offered / ordering something that is out-of-stock. none of that hardware/software will currently exist. nor will any 'procedures' exist for 'management' to keep the 'updating routine' up-to-date.
I'm sure I don't understand your efforts; especially as you expect to release a test version shortly.
virtually nothing electronic - without change to existing hardware/software - will function in any fashion in a paper menu oriented eatery which writes paper tickets that are relayed, on paper or electronically, to the kitchen.
if the eatery has electronic communications/tickets to the kitchen, any 'supplemental' system - other than an electronically presented menu - will require an interface to the existing electronic system - that interface does not exist in the existing system and will require a custom interface in your software to work, and you'll need a lot of proprietary information from "the other system" to construct such an interface, along with quite likely major software modifications to 'the other software' and some kind of hardware integration to go to an open wireless from a closed user environment.
I wish you good luck with the project.