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Information about the Apollo CPU and FPU.

Is the 68080 Soft Core Available On Its Own?page  1 2 3 

Gunnar von Boehn
(Apollo Team Member)
Posts 4795
25 Apr 2020 10:18


Lets provide some information.

The previous 68K models did had different "pinouts".
This means 68000 and 68030 and 68040 are incompatible from "socket".
This means for each socket you need a different adapter platine.
The V500 is designed to be a chip-replacement for the 68000 socket.

The previous 68000 chips worked with different voltages.
This means on the replacement PCB you need level shifters to translate the voltage levels.

An FPGA can not be used "naked" but need circuit to create the needed voltages for it to operate, it needs a flash chip to hold the  image, it need an JTAG plug to be updateable, and you need driver chips data bits for the "socket".

This means there is NO naked options for this.

To make a CPU replacement you need a PCB with a lot of chips of parts on them. The V4 for example has over 100 Caps to maintain the power of the FPGA stable.

To make a "pure" CPU replacement PCB you need a lot of parts.
The PCB, the socket, the FPGA, the flash chip, 100 caps, the voltage circiuts, the levelshifters, the jtag

The FPGA used on the V4 alone has a list price of over $100



Stefan "Bebbo" Franke

Posts 136
25 Apr 2020 18:30


Gunnar von Boehn wrote:

Lets provide some information.
...
 
  The FPGA used on the V4 alone has a list price of over $100

Yeah, it's not for free.

What about upgrading to the cyclone 10 series?

/duck


Gunnar von Boehn
(Apollo Team Member)
Posts 4795
26 Apr 2020 05:28


Stefan "Bebbo" Franke wrote:

What about upgrading to the cyclone 10 series?

What Cyclone10 you mean? There are 2 series.
The LP and the GX.


Gsteemso Del Canuckistan

Posts 7
27 Apr 2020 17:22


Gunnar von Boehn wrote:

Lets provide some information.
 
  The previous 68K models did had different "pinouts".
  This means 68000 and 68030 and 68040 are incompatible from "socket".
  This means for each socket you need a different adapter platine.
  The V500 is designed to be a chip-replacement for the 68000 socket.
 
  The previous 68000 chips worked with different voltages.
  This means on the replacement PCB you need level shifters to translate the voltage levels.
 
  An FPGA can not be used "naked" but need circuit to create the needed voltages for it to operate, it needs a flash chip to hold the  image, it need an JTAG plug to be updateable, and you need driver chips data bits for the "socket".
 
  This means there is NO naked options for this.
 
  To make a CPU replacement you need a PCB with a lot of chips of parts on them. The V4 for example has over 100 Caps to maintain the power of the FPGA stable.
 
  To make a "pure" CPU replacement PCB you need a lot of parts.
  The PCB, the socket, the FPGA, the flash chip, 100 caps, the voltage circiuts, the levelshifters, the jtag
 
  The FPGA used on the V4 alone has a list price of over $100
 

As you present it here, I agree with your analysis in all respects; however, this assessment presupposes a requirement that a "pseud080", to coin a term, must function as a drop-in replacement for one of the earlier models in the 68k line. That makes perfect sense from the context you work in, and I quite agree that such a product would not be in any way economical.

The thing is, for an '080 to be properly useful as a raw component, it must be as flexible and generic as any other raw component. Designing only for similar assumptions as for any other simple microprocessor, the whole thing becomes much more straightforward.

Fundamentally, the entire purpose of the unit can be summed up as "hide the obnoxious complications that using an FPGA rather than a normal IC inflicts on someone's design". The whole thing is aimed at developers, be they hobbyists or otherwise; it's something one would buy when seeking to build any system using "a modern '080 CPU". Whether that would be a device for retrofitting vintage hardware or an entirely new system is outside the scope here, and should play no role in design decisions.

Among other things, new and modern designs for ICs do not presuppose legacy voltage levels. If most other components in a system can be expected to assume, as a generic and arbitrary example, 2.5V I/O -- which the Cyclone V is spec'd to accommodate -- then expensive and cumbersome level shifters and such would be redundant; conversely, if the purchaser wanted 5V (or 12V, or 600V, for all it matters here) I/O, that's their prerogative and they can work out the details to suit their specific purposes.


Gsteemso Del Canuckistan

Posts 7
27 Apr 2020 17:54


Ali B. wrote:

  I am sorry for being rude, but I am just suffering from curiosity:
  What is your experience or qualification in / for kicking off such an effort and what would be your share regarding the groupís work?

Not rude at all! I would be equally puzzled, in your shoes.

My motivation is straightforward; primarily, I want to be able to buy a 68080 to play with. As that's not actually possible right now, even though it could be with some effort (but much less so than the Apollo team has invested in designing the core itself), in the absence of anyone else acting I shall have to take it up myself.

I'm not sure I can claim "qualifications", exactly, as I have not formally earned any certification an employer might care about. I know enough electronics to comfortably understand what I'm designing. I do not have and will not pretend to have extensive hands-on experience, as the overwhelming majority of my efforts over the past 20 years have been design-only, but I know enough people locally who do have current and highly-relevant skills in this area that I am confident of producing a useable result.


Gsteemso Del Canuckistan

Posts 7
27 Apr 2020 18:08


To clarify, the reason my confidence is boosted by knowing knowledgeable and experienced people locally is that I can ask them about things like the subtle pitfalls of homebrew circuit-board design before making potentially catastrophic missteps. I am not going to be expecting random friends and acquaintances to do any of the actual work.

That said, once I have a design I'm reasonably satisfied with I'll be putting it up somewhere for public review. I feel it would largely defeat the purpose of this whole business unless my own part of it was freely available.

Ultimately, the hardware part is necessary but not sufficient; once that's out of the way is when I expect to be doing most of the interaction with Gunnar et al.

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