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

[Lionel Peterson]

I imagine 370s used microcode, at least anything after, say, 1428 machines... I guarantee you anything after the 3090 series did.

The AS/400 used microcode as well, as well as the last 15 or so generations of Intel CPUs.

Does that mean that there are no 'real' processors anymore since everything uses microcode?

I think if a piece of silicon executes the op codes I feed it, it's a real CPU. If a program running outside the silicon does some sort of translation, it's emulation.

Microcode, being implemented on the wafer, is not emulation - it is what the chip is.

But that's just my opinion...

Ken

> On Sep 12, 2023, at 17:42, Joshua Boyd via rescue <rescue at sunhelp.org> 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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