Differences between JLink V8 and Jlink v9:
Speeds: V8 supports up to 10M (JTAG debugging mode)/4M (SDW debugging mode), while Jlink V9 supports up to 20M (JTAG debugging mode)/15M (SDW debugging mode).
Stability: V9's drive IC has the ability of voltage adaptation, which can automatically adapt to the cpu voltage of the target board when the wiring is correct. Both 1.8-5.5V CPUs can be debugged, while V8 can only debug 3.3V CPUs, and the stability of debugging 5v cpu is poor.
Jlink V8 is easy to lose its firmware. Many V8s have hung up, and need to rewrite the firmware. Ordinary users can only let it be, while V9 does not.
V8 no longer support some of the latest CPU , while V9 supports almost all ARM CPU.

Features of JLINK V9:
The main control chip is STM32F205, without losing the firmware, and the hardware has been upgraded to the latest version of V9.4
It can provide 3.3V voltage 0.8A current for the development board (The second pin)
Support standard JTAG interface and 2-wire SWD debugging interface. The speed can reach 20M (JTAG)/15M (SWD) per second.
It supports debugging of all ARM chips, MDK or IAR, and compilation environment IDE supported by other standard JLinks.
Original firmware, full automatic firmware upgrade.

J-Link ARM Features:
IAR EWARM integrated development environment seamlessly connected JTAG Emulator
Support all ARM7 / ARM9 core chips, as well as cortex M3, including Thumb mode
Support for ADS, IAR, KEIL, WINARM, REALVIEW almost all of the development environment
Download speeds of up to ARM7: 600kB / s, ARM9: 550kB / s, through the DCC up to 800 kB / s
The maximum JTAG speed 12 MHz
Target board voltage range 1.2V-3.3V, 5V compatible
Auto speed recognition
Monitoring all JTAG signals and target board voltage Fully plug and play
Use the USB power supply (but not the target board power supply)
With a USB cable and 20-core flat cable
Support multi-device JTAG serial connection
Standard 20-core JTAG emulation connector
Optional 14-core JTAG emulation connector
Optional adapter for 5V targets board
J-Link Support for ARM Kernel:
ARM7TDMI (Rev 1)
ARM7TDMI (Rev 3)
ARM7TDMI-S (Rev 4)
ARM720T * ARM920T
RM926EJ-S
ARM946E-S
ARM966E-S
ARM11
Cortex-M3


Packing List:
1x Jlink V9.0 Emulator
1x 20P Line of a Standard JTAG
1x USB cable