A facility for detecting writing errors in some magnetic tape systems consisting of using a second head adjacent to the writing head to read data immediately after it is written and to compare it with the original data as held in a buffer.

• 一种检测某些磁带系统写入错误的设施，这些磁带系统使用写入磁头旁边的第二个磁头在数据写入以后立即将其读出，并将它们与在缓冲器中的原始数据相比较。