Following a suggestion by Alan Cox I looked at the 8085 undocumented instructions. They actually make the 8085 a halfway decent target for stack argument passing, as well as handling subtraction and right shifts of 16-bits. So I added support to those instructions in sdasz80 but with Z80 style mnemonics as the first step.

If I ever target the 8085 I'm inclined to start the code generator from scratch as the hack of the Z80 code generator for 8080 could be unmaintainable even if I get the right shift working. Many of the library routines require reentrancy so it will be necessary at some point to turn back on stack argument passing and suffer the horrible inefficiency and wake up latent bugs. ☹️