... had the LDM instruction, "load memory with immediate". It also had a T flag, which allowed the X register to point to a ZP "accumulator" for some ... 2 cycle penalty)
INX

[...] ; and so on for byte 2, byte 3 etc
The Hudson Soft HuC6280 also features the T flag, but IIRC Hudson Soft's ...

... of simplified 65E4. I believe that your proposal might benefit from the Hudson T flag , although, by graph coloring, there is diminishing return when a 3-address machine has more than six symmetric registers.

About six months ago, I proposed atomic instructions without much success. After reading the ...

... in the realm of enhancements which *did* get implemented, I think the T Flag (a new bit in the Processor status register, included in the Hudson Soft HuC6280 and certain other CPU's) is worth remarking. From this post in the thread 65x02 variants : When the T flag is set, the accumulator is replaced ...

... pointed to by X as an accumulator. This is enabled with the new T flag.
-The M50734 for example seems to divide its clock by 4. You can see two ... like that series divides the clock by two instead of four.

How about adding the HuC6280 to the list? https://en.wikipedia.org/wiki/Hudson_Soft_HuC6280

... here before , although I'd forgotten it.

The [PC-Engine] uses the Hudson Soft 6280 , a 6502 variation which we have discussed before . It's got a ... instructions such as SAX, SAY and BSR) are undeniably cool, but the T Flag is a fundamental improvement, IMHO. Much though we all love the 65xx ...

... in the assembler I use
clc
adc #$20
sta <$30
cla
adc #$00
sta <$31


T flag code:

ldx #$30
clc
set
adc #$20
inx
set
adc #$00

The contents of A are ... mostly HK and JP sites). I know both the HuC6260 and HuC6270, both by Hudson, are easier to find but they aren't CPUs (graphic processors to ...

... Rockwell variant (with the extra RMBi,SMBi,TRB,TSB,etc opcodes) made by Hudson.

the URL above is my normal source, plus this Commodore-related page ... 6502.org/users/andre/csa although my MMU is external.

SET - set the T flag. The T flag is right between the V and B flag. When the T flag is set ...

... Rockwell variant (with the extra RMBi,SMBi,TRB,TSB,etc opcodes) made by Hudson.

Just a quick list of features..

Swap register instructions - SAY, SAX, SXY. They don't effect flags, so it can be useful for using two regs to do 16bit adds or shifts.

Branch instructions that cross a page boundary ...