Is it a requirement to have a printer connected to the payment terminal?

The Cash Register System Regulation does not require the payment terminal to be able to print receipts.

According to Section 2-3 first paragraph of the Cash Register System Regulation, cash register systems must be equipped with a printer at each point of sale. Among other things, the printer must be able to produce sales receipts. In the case of integrated payment terminals, sales receipts must also state the transaction ID of the terminal; see Section 2-8-4 of the Cash Register System Regulation. However, the Regulation does not require it to be possible to produce printouts from payment terminals which are not integrated. If the payment terminal is able to produce a receipt for a payment, the receipt - whether paper-based or electronic - must comply with Section 2-8-8 of the Cash Register System Regulation:

Section 2-8-8          Receipt from payment terminal

Receipts from a payment terminal which is not integrated with the cash register system must be clearly marked ‘IKKJE KVITTERING FOR KJØP’ (‘NOT A PURCHASE RECEIPT’). The font of the marked text must be at least 50% larger than the text that shows the amount.