The first assignment series (DFD)

In the name of the Most High
The first series of SAD Course assignments :
1- Exercises number 10, 11, 13 and 14 from 9th chapter of the textbook (Modern
System Analysis and Design).
2- What are the differences between data flow diagrams and program flow charts?
3- Given the following narrative description, draw a physical context data flow
diagram and the next level of it:
The purpose of the Green Acres Real Estate Information System is to assist
agents as they sell houses. Sellers contact the agency and an agent is assigned to help
the seller complete a Sales Request Form.
Information about the houses and lot token from that form is stored on a computer
disk file. Personal information about the sellers is copied by the agent onto a Seller
Personal Info Sheet and store in a filing cabinet. When a buyer contacts the agency,
he or she fills out a Buyer request.
Every two weeks, the agency send prospective buyers a homes-for-sale magazine and
a key for the magazine containing street addresses. Periodically the agent will find a
particular house that satisfies most or all of a specific buyer’s requirements, as
indicated in the Buyers Requirements Reports distributed weekly to all agent. The
agent will occasionally photocopy a picture of the house along with vital data and
send the Multiple Listing Service Sheet to the potential buyer. When the buyer select
a house, she or he fills out a Purchase Agreement that is forwarded through the real
estate agency to the seller, who responds with an Offer Acceptance or a CounterOffer.
After a Purchase Agreement has been accepted, the agency sends an Appraisal
Request to an appraiser, who appraises the value of the houses and lot. The agency
also notifies its finance company with a Financial Request Form.