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

[Mike Katz]

The problem is that most modern microprocessors are microcoded, 
including the 68000, LSI-11, etc.



On 9/12/2023 5:41 PM, Joshua Boyd via rescue wrote:
> On 9/12/23 18:08, Lionel Peterson via rescue wrote:
>> Emulating a 68000 to emulate a 370?
>>
>> At some point it starts to resemble the light 'hack' in an early 
>> big-bang theory episode:
>>
>> https://youtu.be/onZ4KMM94yI?si=AZGAKQr5QvL3yZrD
>>
>> I mean I get it, but...
>
>
> 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.
>
>
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