From: already5chosen@yahoo.com   
      
   On Sat, 08 Nov 2025 18:25:18 GMT   
   anton@mips.complang.tuwien.ac.at (Anton Ertl) wrote:   
      
   > EricP  writes:   
   > >What architecture cannot do an indirect branch, which I assume   
   > >means a branch/jump to a variable location in a register?   
   >   
   > Or, in case of the 6502, in memory.   
   >   
   > I don't know of any architecture (except maybe some one-instruction   
   > proof-of-concepts) that does not have indirect branches in one form or   
   > another, but I am not that familiar with architectures from the 1950s   
   > or some of the extremely deprived embedded-control processors.   
   >   
   > Maybe the thing about self-modifying code was thrown in to taint the   
   > assigned goto through guilt-by-association.   
   >   
   > >Even if an ISA did not have a JMP reg instruction one can create it   
   > >using CALL to copy the IP to the stack where you modify it and   
   > >RET to pop the new IP value.   
   >   
   > In most cases that is possible (even if the return address is stored   
   > in a register and not on the stack), but the return addresses might   
   > live on a separate stack (IIRC the Intel 8008 or the 8080 has such a   
   > stack), and the call might be the only thing that pushes on that   
   > stack.  But yes, in most cases, it's a good argument that even very   
   > deprived processors usually have some form of indirect branching.   
   >   
   > - anton   
      
   I would imagine that in old times return iinstruction was less common   
   than indirect addressing itself.   
      
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