[rescue] [OT] S: IBM /370 or /390 card

[Dave McGuire]

On 9/12/23 18:41, Joshua Boyd via rescue wrote:
> If we are going to call the XT/370 an emulator, then isn't a Motorola 
> 68000 chip just also an emulator?  As I understand it, when you get to 
> microcoded chips, there is no actual hardware that runs the actual 
> binary instruction set sent to the processor. With either the regular 
> 68k or the 370 implemented in 68k microcode, the CPU reads an 
> instruction of the either 68k or 370 origin, then looks that up in ROM 
> for how to execute it.
> 
> Now, is a gate level re-implementation of a 68k on an FPGA emulation? If 
> so, then I suppose that means anything on an FPGA is emulation. Is a 
> blackbox external "reimplementation" of a 68k on an FPGA or ASIC 
> emulation? The MiSTer people, to my understanding, state that it isn't 
> but I feel suspicious about that, and would probably err on calling that 
> emulation.  What if it was a blackbox re-implementation but could run 
> original microcode? I probably don't want to even debate that one.

   We are rehashing the age-old argument of "what is emulation".  All 
IBM S/390 processors are microcoded; the micromachine doesn't understand 
the S/390 instruction set until the microcode is loaded from the console 
system.  This is the case for nearly everything; most processors are 
microcoded.  You know all of this, having stated that you don't want to 
debate it. B-)

              -Dave

-- 
Dave McGuire, AK4HZ
New Kensington, PA