The Tiny-99/4A v2 reacts as the original TI-99/4A, so it can receive a TIM device or a SAMS card.
For SAMS installation, I added a jumper to disable the onboard 32Kb expansion. At a time, I considered the integration of the SAMS device on the PCB but I made the choice a tiny PCB and there is already a very concentrated population of ICs on it (It's the reason why the PCB has 4 layers). Adding the SAMS would have increase the size of the board. But as the computer has 3 expansion slots, I said to myself that it was always possible to install the SAMS board if necessery. This is why I added the jumper to disable the onboard 32K RAM.
The computer integrates a extented 32 Kb ROM, it's a user ROM, so it can contains what one wants. (Currently, the v2 that I use contains Editor/Assembler II r2). This extra ROM is automaticly disable when a cartridge is plugged to prevent conflics.
There is a special case: To be compatible with the FinalGROM, I had to add jumpers that disable the extra ROM. This is not a real limitation because if someone has the FinalGROM, this 32Kb extra ROM has less interest.
The Tiny-99/4A v2 integrates a RTC based on the MM58167. So it will conflicts with the clock feature of the PGRAM. I haven't considered to disable the RTC on my computer, so there's no jumper. It's not a choice but a forgetting (whoops!) , But the traces of the control lines of the MM58167 are on the top and bottom layers of the 4 layers PCB. So, it's easy to disable the onboard RTC.