OK, Done.

The program works as far as I tested it. It reads and writes into the FT-1900R (i.e., memory content).

The details:

The memory record (structure) is 2-bytes longer, seems that it include the tone also, maybe other stuff, I did not check.

Memory location: 76Eh

Memory status: 6EEh

All the rest seems to be exactly like the 1802.

The program, and some dumps are attached.

Some observations:

When changed from VFO to MEM, 0EAh changed from 01h to 02h, 0168h changed from 73h to 74h, 16Ah: 01h->02h, 01E8: 73h->74h.

After Adding memory content M1 (145625K), 0EBh: 01h->02h, 0168h changed from 74h to 75h, 16Bh: 02h->01h, 01E8: 74h->75h.

In addition, it replaces 144000K with 145625K at 3B0h, 144000K was the initial VFO freq after factory reset. (in addition, it stored the frequency in place, i.e., at 0784h, and updating mem index in 06eFh – from 03h to 33h.)

Adding 148715K into M2 changed memory holding (or vfo) at 03B0h (3bytes of channel in bbcd), as well as changed the required memory record (at 0798h) and mem index (06EEh: 00->03h).

Changing the channel/memory name of M2 simply changed the 6-bytes name at 079Ch.

Last, I added 145325K into M3, while for some reason changing into this frequency turned duplex on with – shift (I did not change anything from factory reset regarding this, so maybe it got it from old memory content). This had several changes, apart from the memory record/structure. First, as usual, 03B0h changed into the new frequency. Second, 03EEh changed from 00 to 01 (duplex?). Then, mem index changed (06EEh: 03h->33h) and the mem freq changes (at 07ACh). Additionally, the byte before the frequency, i.e., flags, changed from 01h into 0Ch (like when I added M1 and M2).

Saving M3 again (after setting up tone into 91.5 (was 100 by default), changed 14Bh: 00->33h, 168h: DE00 0202 0000 0000 ->  AB00 FFFF FFFF FFFF, and approximately the same at 1CBh and 1E8h. This is, of course, in addition to handle the M3 record: after the freq shift value (006000), it changes the flags at 7B8h: 0Ch->09h, and again the unknown flags at the extension 07BDh: 0Ch->09h.

Best, Ran