ATR statistics: TB2 - Global, deprecated

Article from the series "ATR statistics"

TB2 - Global, deprecated

The ISO 7816-3 specification is not public. So I can't copy/paste part of the text. I will use Wikipedia instead.

From Wikipedia https://en.wikipedia.org/wiki/Answer_to_reset#Interface_byte_TB2

TB₂, if present, is global. The usage of TB₂ is deprecated since the 2006 edition of the standard, which prescribes that cards should not include TB₂ in the ATR, and readers shall ignore TB₂ if present.

In the 1997 edition of the standard, TB₂ (8th to 1st bit) encode PI2, which when in range 50..250 (other values being RFU) encode V_PP in increments of 0.1 V, and subsumes the coarser indication given by PI1 of TB₁. Refer to that section for why modern Smart Cards have no use of V_PP, and thus of TB₂.

Historical note: Provision for TB₂ did not exist in ISO/IEC 7816-3:1989, and was introduced because V_PP = 12.5 V became a popular value in EEPROM technology, replacing 25 V and 21 V.

TB2	#	%
	2070	99.90 %
0x3F	1	0.05 %
0x45	1	0.05 %

Only 2 cards use a TB₂ value.

• 3B FF 00 FF 81 31 00 45 65 63 00 00 00 00 00 00 00 00 00 00 00 00 00 00
• TB₂= 0x45 Programming param PI2 (PI1 should be ignored): 69 (dV)
• This card also has TB₁ = 0xFF Programming Param P: 31 Volts, I: RFU 
• 3F FF 3F 3F 3F 3F 00 3F 3F FF 3F 3F 3F 3F 3F FF 3F FF 95 3F FF 95 3F FF
• TB₂ = 0x3F Programming param PI2 (PI1 should be ignored): 63 (dV)
• This card also has TB₁ = 0x3F Programming Param P: 31 Volts, I: 50 milliAmperes  

I agree these 2 ATRs are quiet unusual.