Microsoft Access attempts to display binary, varbinary, and timestamp fields as ASCII characters. If the data in one of these field types coincidentally corresponds to an ASCII character you may see strange letters or numbers. If there is no ASCII equivalent, the field will appear to be blank. This is discussed in Knowledge Base article Q121834 ACC, "Linked SQL Server Binary Data Displayed Incorrectly."
The SQL Server timestamp data type has no counterpart in Microsoft Access. In spite of its name, it is neither a time nor a date, nor is it some encoded representation of a time or date. When the Upsizing Wizard adds timestamp fields to a table it names them upsize_ts. If you query "SELECT upsize_ts FROM tablename" from an upsized table, a value similar to 0x0000000100002057 is returned. This is a hexadecimal representation of a number, so it often contains the letters a, b, c, d, and e. A timestamp is a number that increases each time it is used. The timestamp column on a table gets a new value each time it is updated. This permits the client program to confirm whether values have changed since it last checked the record.
The timestamp field indicates only that a record was changed, not when it was changed. You cannot set the timestamp column to any specific value. Because this data type does not have a corresponding Microsoft Access data type, it cannot be displayed in the Microsoft Access user interface.