This can be quite expensive only one key is used and

this can be quite expensive, only one key is used and moreover, the data cannot be accessed
sequentially. All of the records that make up a sequential file are stored according to the control key
associated with it. With every organization, efficiency is key, this might be the reason that organizations
utilize sequential file access. When files are stored sequentially they are simple to understand, easier to
organize and maintain, economical, unlike direct access which utilize hard disks and any errors contained
in the file remain localized.
Explain in your own words the importance of the stored-program concept. Include the role of the
control unit in your explanation.
What is a blade server, and why have blade servers become important in the last few years?