I thought I would share my opinion if it is worth getting or not.
jrIDE compatibility:
It does indeed work right along side a jrIDE. I have included a screenshot from the memory timings using the Quarterdeck Manifest utility. As you can see, the fast 512K is coming from the MCL86jr. The first 128K is from the memory onboard the PCjr and the last 96K is provided by the jrIDE. It's nice to know you can still use this with a jrIDE and have that level of compatibility.
PCjr sound:
The PCjr audio in all of the programs I have tried does not work when running in the MCL86jr in unlocked mode. The audio will work if you put it back to cycle accurate mode. This is really a shame however, but not unexpected.
General program compatibility:
Outside of the PCjr audio issue, most software does run as expected including MS-DOS 6.22. Notable exceptions are Cartridge BASIC, TOPBENCH and Landmark 6.0. None of these will run even in cycle accurate mode. Cartridge BASIC will not initialize. TOPBENCH will startup, but when attempting to run the benchmark, it just freezes. Landmark 6.0 will startup and then exit abruptly.There are surely more programs that will have issues, but this is what I have run into so far.
Is it worth getting an MCL86jr? The answer is no, due to the compatibility issues I have encountered. You are far better off with a NEC V20, better yet one in PC-Sprint. Now if you have a spare PCjr sitting around, this does make a great computer for doing development work or running productivity software. I have three PCjrs and the one I put this in was just sitting in my closet as a spare. There has been no development of the 8088 core on the MCL86jr since 2020. If that ever got updated and the compatibility issues fixed, then this would be a no brainer to put into a PCjr. Pending that happening you should look elsewhere.
jrIDE compatibility:
It does indeed work right along side a jrIDE. I have included a screenshot from the memory timings using the Quarterdeck Manifest utility. As you can see, the fast 512K is coming from the MCL86jr. The first 128K is from the memory onboard the PCjr and the last 96K is provided by the jrIDE. It's nice to know you can still use this with a jrIDE and have that level of compatibility.
PCjr sound:
The PCjr audio in all of the programs I have tried does not work when running in the MCL86jr in unlocked mode. The audio will work if you put it back to cycle accurate mode. This is really a shame however, but not unexpected.
General program compatibility:
Outside of the PCjr audio issue, most software does run as expected including MS-DOS 6.22. Notable exceptions are Cartridge BASIC, TOPBENCH and Landmark 6.0. None of these will run even in cycle accurate mode. Cartridge BASIC will not initialize. TOPBENCH will startup, but when attempting to run the benchmark, it just freezes. Landmark 6.0 will startup and then exit abruptly.There are surely more programs that will have issues, but this is what I have run into so far.
Is it worth getting an MCL86jr? The answer is no, due to the compatibility issues I have encountered. You are far better off with a NEC V20, better yet one in PC-Sprint. Now if you have a spare PCjr sitting around, this does make a great computer for doing development work or running productivity software. I have three PCjrs and the one I put this in was just sitting in my closet as a spare. There has been no development of the 8088 core on the MCL86jr since 2020. If that ever got updated and the compatibility issues fixed, then this would be a no brainer to put into a PCjr. Pending that happening you should look elsewhere.
