...then

1. the BASIC program gets natively written directly into FLASH (as an option, you can write it into RAM if you want, but there is a whopping 768Bytes of XRAM in P89V51RD2 and BASIC eats 512B of it for its internal purposes, so you are left with 256B for your program AND data... :-) )

2. there is a support for accessing a portion of FLASH (2kBytes) from BASIC programs byte-per-byte, as if you would access IRAM bytes - using DBY()

3. you always can write your own assembler program and call it from BASIC using either CALL or the extensions mechanism.

Well, maybe not EXACTLY what you'd call IAP, but, is there any more needed under BASIC?

There is only one minor flaw on this all, v1.4beta4 is unreleased yet... :-( But this all works on what's there on my website - the older v1.4beta3, too, although that's for T89C51RD2/AT89C51RD2/ED2 (and the DBY-cludge works for the EEPROM of ED2 only...)

JW