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 Pentium III Game Console 

When I complete this project, would you attempt to make it too?
Yes 0%  0%  [ 0 ]
Maybe 100%  100%  [ 2 ]
No 0%  0%  [ 0 ]
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 Pentium III Game Console 
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Joined: Tue Jan 15, 2013 5:43 am
Posts: 183
FloppidyDingo wrote:
the Pentium III data sheet says that the CPU may operate incorrectly with a clock input of anything other than 100 MHz. I don't see how underclocking could cause issues
One possible reason for sticking to 100 MHz is because an on-chip Phase-Locked Loop (PLL) is used to multiply the original 100 MHz to obtain 600 MHz (or whatever the internal frequency is). PLL's aren't trivial to design, so they've made the job easier by sticking to 100 MHz input -- otherwise there'd be one more variable the PLL design needs to accommodate.

How's your 68K computer coming?

-- Jeff

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Tue Dec 01, 2015 1:07 am
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Joined: Thu Oct 08, 2015 11:57 pm
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Dr Jefyll wrote:
One possible reason for sticking to 100 MHz is because an on-chip Phase-Locked Loop (PLL) is used to multiply the original 100 MHz to obtain 600 MHz (or whatever the internal frequency is). PLL's aren't trivial to design, so they've made the job easier by sticking to 100 MHz input -- otherwise there'd be one more variable the PLL design needs to accommodate.

How's your 68K computer coming?


Oh yeah, the PLL. I forgot about that. I'll just do circuit simulation before I order the board. Also, the chip I have is 800 MHz internally.

The 68K computer is almost finished. Hardware wise. I just need to spend a good session or four to finish the soldering job. For software, I've been getting lazy. I should probably start it. I'm going to set up my Raspberry Pi as a BIOS flasher, and I'm writing a rough draft on what I want my OS to look like. I'll post about it in the other thread so I don't mix it with this one too much. So far nothing exploded, so that's good.

But while I'm on the subject of circuit simulation, I found this site to help me: https://easyeda.com/
Along with being an online simulator, I can also order up to 6 layer boards from them. I'm still looking at it myself, but do you think it would be sufficient for my needs?


Tue Dec 01, 2015 1:19 am
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FloppidyDingo wrote:
I can also order up to 6 layer boards from them. I'm still looking at it myself, but do you think it would be sufficient for my needs?

I think this entire project will take on a startling, new aspect for you after you've gotten your 68K working.

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Tue Dec 01, 2015 1:49 am
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Dr Jefyll wrote:
I think this entire project will take on a startling, new aspect for you after you've gotten your 68K working.


I'm scared... It's been my life long dream to build this console, and I don't want it to end up as a flop. But you're right, 68K first, console later. I posted a brief about my planned OS.


Tue Dec 01, 2015 2:08 am
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Joined: Sat Jun 16, 2018 2:51 am
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Hi
If you haven't already come across these resources, here are some nice ones related to Game Console design.

The MiSTer Project
"MiSTer is an open project that aims to recreate various classic computers, game consoles and arcade machines, using modern hardware. It allows software and game images to run as they would on original hardware, using peripherals such as mice, keyboards, joysticks and other game controllers."

Game Console Architecture Series (by RTL Engineering)
"Series about emulating late 90s era game consoles using hardware instead of software."

Game Engine Black Book Series (by Fabien Sanglard)
The chapters at the end talk a bit about the architecture of the popular consoles of the time.


Tue Jun 16, 2020 8:52 pm
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Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1419
Quite a few good blogs too on Fabien's site, picking apart how games were implemented on various platforms:
https://fabiensanglard.net/


Tue Jun 16, 2020 9:08 pm
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To be honest I completely forgot about this project. And to be fair back when I first started this I had no idea what I was doing. Now I want to revisit this having a lot more experience in electronics. I can already tell this will still be interesting. DDR3 routing is hard enough as it is. These seem like goo links to take a look at though, thank you!


Tue Jun 16, 2020 9:17 pm
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Joined: Mon Oct 07, 2019 2:41 am
Posts: 112
Dr Jefyll wrote:
FloppidyDingo wrote:
the Pentium III data sheet says that the CPU may operate incorrectly with a clock input of anything other than 100 MHz. I don't see how underclocking could cause issues
One possible reason for sticking to 100 MHz is because an on-chip Phase-Locked Loop (PLL) is used to multiply the original 100 MHz to obtain 600 MHz (or whatever the internal frequency is). PLL's aren't trivial to design, so they've made the job easier by sticking to 100 MHz input -- otherwise there'd be one more variable the PLL design needs to accommodate.

How's your 68K computer coming?

-- Jeff

Several cpu designs don't use real latches and flip/flops but rather small capacitor
to hold information for a very small amount of time, say 1/4 of your of your master
clock. 100 Mhz clock is 10 ns, and your latch can just hold data for 2.5 ns. Longer than
that *poof* your computer stops working.My guess is that is why you can't under clock.
Ben.
PS: Don't forget the Japanese consoles.


Wed Jun 17, 2020 8:10 am
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