Operating System Concepts says:
Devices vary on many dimensions, as illustrated in Figure 13.7.
• Character-stream or block. A character-stream device transfers bytes one by one, whereas a block device transfers a block of bytes as a unit.
• Sequential or random access. A sequential device transfers data in a ﬁxed order determined by the device, whereas the user of a random-access device can instruct the device to seek to any of the available data storage locations
Does block device imply random access?
Does random access imply block device?
Does character device imply sequential access?
Does sequential access imply character device?