High Risk Credit Card Processor

I’m looking for answers to a question as to how point of sale (POS) software works.?

There are several hardware interface standards for point of sale (POS) systems – OPOS, JavaPOS, UnifiedPOS. However, I’m wondering whether when a credit/debit card scanner runs a card it connects to the credit card processor itself or whether it sends information on the card back to the main POS system, which then connects to the processor to process the card?

The POS system would need to connect to a banking service to verify the cards.

You can either run the credit card reader through your PC or via a stand-alone credit card terminal.

There are positives and negatives of running credit cards through your PC.
Positive: Your POS system should keep a record of all transactions and tie them back to your credit card transactions.
Negative: If your PC crashes, you won’t be able to accept credit cards at all (as opposed to writing down sales manually and then processing them through the stand alone credit card terminal.)

Intuit QuickBooks Point of Sale: Integration with Intuit Merchant Services