Rev.A ⇒ Rev.B

Rev.B was released to solve the JTAG communication error that occurred in Rev.A.
Please see the information below for the conditions under which the error occurs when using Rev.A.

https://www.altera.com/support/support-resources/knowledge-base/solutions/rd05122004_8687.html

• difference in appearance
• Change from flat cable to flexible cable
• Change of Rev seal or marking (no seal, Rev.A ⇒ Rev.B)

Rev.B ⇒ Rev.C

Implemented further noise countermeasures from Rev.B.
Please see the information below for the conditions under which the error occurs when using Rev.B.

https://www.altera.co.jp/support/support-resources/knowledge-base/solutions/rd06292006_529.html

• RoHS compliant
• Changes to the electrical characteristics of the JTAG interface (See the USB-Blaster™ Download Cable User Guide and search for DC Operating Conditions or Operating Conditions for information on the changes in characteristics.)

https://www.altera.com/en_US/pdfs/literature/ug/ug_usb_blstr.pdf (English)
https://www.altera.co.jp/ja_JP/pdfs/literature/ug/ug_usb_blstr_j.pdf (Japanese)

There is also a description about Revision in the User's Guide, so please refer to it as well.