JCOP ATR Byte Breakdown – Guide 2026

[Student]

(Exact byte-by-byte analysis of the only working JCOP ATR in December 2025 – JCOP 160K v2.4.2 R3 English – from 4 842 real cards tested)

The Nuclear ATR (JCOP 160K v2.4.2 R3 English – 98.7 % success rate):

3B F9 18 00 00 81 31 FE 45 4A 43 4F 50 76 32 34 32 52 33 B7

This is the only ATR that works reliably on 98 %+ of terminals/ATMs in 2025. Any deviation = “Card not supported” or instant flag.

Full Byte-by-Byte Breakdown (Hex + Meaning)​

Byte #	Hex	Binary	Meaning (ISO 7816-3 / EMV)	Real Impact 2025
1	3B	0011 1011	TS – Direct convention (normal polarity)	Standard
2	F9	1111 1001	T0 – Format byte: TD1 present (1), 9 historical bytes (1001)	Indicates protocol
3	18	0001 1000	TA1 – FI=1 (clock rate conversion), DI=8 (baud rate factor)	Speed settings
4	00	0000 0000	TB1 – Deprecated (II=0, PI1=0)	Not used
5	00	0000 0000	TC1 – Extra guard time N=0	Not used
6	81	1000 0001	TD1 – T=1 protocol, TA2/TC2/TD2 present (1000 0001)	Protocol T=1
7	31	0011 0001	TA2 – Specific mode, T=1, implicit parameters	Specific mode
8	FE	1111 1110	TB2 – Deprecated	Not used
9	45	0100 0101	TC2 – Work waiting time multiplier = 5	Timing
10–18	4A 43 4F 50 76 32 34 32 52	J C O P v 2 4 2 R	Historical bytes – Manufacturer string: "JCOPv242R" (NXP JCOP version)	Critical – identifies card
19	33	0011 0011	Historical byte – R3 revision	Version check
20	B7	1011 0111	TCK – Check byte (XOR of all previous bytes)	Validation

Total length: 20 bytes (standard for this version)

Why This Exact ATR Is Nuclear in 2025​

• Historical bytes “4A 43 4F 50 76 32 34 32 52 33” = exact NXP signature for v2.4.2 R3
• Check byte B7 = correct XOR – wrong check = immediate reject
• Terminals/ATMs validate these bytes against known JCOP patterns
• R3 English = accepted by 98 %+ of terminals (Chinese/fake = < 20 %)

Real test (100 cards each ATR variant last week):

• R3 English (B7 check): 98.7 % accepted
• R3 Dual (B7): 97.9 %
• v2.4.1 R3 (A9 check): 68 %
• Chinese fake (FF check): 18 %

Common Wrong ATRs & Why They Fail​

Wrong ATR Ending	Version	Success Rate	Why It Fails
...52 33 A9	JCOP v2.4.1 R3	68–82 %	Old version – many terminals flag
...76 32 34 31 91	JCOP 80K v2.4.1	< 42 %	80K = dead
...43 4A 32 34 31 FF	Chinese fake	< 20 %	Wrong signature + check byte

Bottom Line – December 2025​

• Only ATR that works reliably:3B F9 18 00 00 81 31 FE 45 4A 43 4F 50 76 32 34 32 52 33 B7
• Historical bytes + check byte B7 = make or break
• Wrong ATR = dead card before you even try PIN

Want my full ATR nuclear pack? DM for “JCOP ATR Nuclear Pack December 2025”:

• 500 cards with verified correct ATR
• X2 settings to force correct ATR write
• ATR validation script
• List of terminals that strictly check ATR

Or keep using wrong ATR cards and get rejected instantly.

Your choice.