Is there a list somewhere of the boards that are now coming with the PKOB4 (which is a pickit4 "on board")?
 
There are two obvious advantages.
the PKOB3 has always been well.. awful. (other words come to mind though), supposedly the PKOB4 will have more or less the same hardware and firmware as the PK4, with all the improvements in programming and debugging speed.
Also, the PKOB4 enumerates a companion virtual com port too that may come in handy.
 
Yes, one can (almost) always connect an external debugger but i believe one cable instead of three is usually better. (why three? 1)power 2)debugger 3)com port))
 
Known Devboards with PKOB4
DM164136 - Curiosity High Pin Count (HPC) Development Board
DM164137 - Curiosity Development Board (recent version)
DM320209 - Curiosity PIC32MZ EF 2.0 Development Board
DM330030 - dsPIC33CK Curiosity Development Board

I think the new Curiosity High Pin Count (HPC).
Read #7 in this thread: https://www.microchip.com/forums/m1121979.aspx
 

Yes, it seems that the new curiosity boards come with the PKOB4 (i was pondering on buying a new 16 or 32bit devboard to experiment with uC/OS now that os and related tools and books have become free)

uC/OS as in Micrium?  Which Version?
 

The Curiosity Low Pin count board supporting 20 pins and below also has the PKOB4

NKurzman
uC/OS as in Micrium?  Which Version?

2,3, whichever (but i'm reading the book on 3). i have to do manual work anyway as the few examples from microchip are from 6 years ago. no RTOS support for PIC32 in harmony 3 either :(

I do not think uC/OS-II or uC/OS-III is free for Commercial Use.  Harmony V1,2  supported  uC/OS ( Not sure about 3), and FreeRTOS.  I heard that Harmony 3 Defaults to FreeRTOS.  The Default for Harmony 1 and 2 was No RTOS.

so you didn't hear the news :) https://www.micrium.com/buy/licensing/
it was in the latest Embedded Muse
 
In any case, whichever RTOS support harmony 3 may support, not for PIC32 is supported, yet. (there are two repositories, one for CMSIS-FreeRTOS so ATSAM only and one for uC/OS-III which is currently only ATSAM)

Known Devboards with PKOB4
DM164136 - Curiosity High Pin Count (HPC) Development Board (recent version)
DM164137 - Curiosity Low Pin Count (LPC) Development Board (recent version)
DM320209 - Curiosity PIC32MZ EF 2.0 Development Board
DM330030 - dsPIC33CK Curiosity Development Board
 

RISC
DM164136 - Curiosity High Pin Count (HPC) Development Board (recent version)
DM164137 - Curiosity Development Board (recent version)

I guess there's not way of knowing when you order which you're going to get? Coincidentally I ordered a backup HPC board a week or so ago as the one I currently have has been seeing a lot of use. After reading this thread I note that the new one does indeed have the PKOB4.
 
All of the Nano boards I have use a "PKOB Nano" debugger, seemingly from the Xplained series as far as a cursory view tells me, but ISTBC. Perhaps that's still PKOB4, but the behavior under the hood seems a little different as far as I can tell.