PPC / 680x0 development help!

[Oli_hd]

Hi

Does anyone have any idea how Phase5 connected the PPC chips to the 68000 bus on the PPC accelerators?

I havent really looked at the board design much or PPC chips for that matter but the bus has probably just been updated like all modern chips, Iints replace IPL's on the chip, berr and halt removed, fc0-2 changed and such like, just like the Motorla Coldfire.

was it with a custom "south bridge" chip?

Nope, it would have a chip to mate it up to the 68K bus, probably one of the CPLD's between the SIMM slots on the Cyberstorm. On the bottom of the cyberstorm, almost below the PPC is what looks like the chip I am using to turn the Ints back to IPL's.
Dont know about AVEC and things like that though.

You should look around Motorola's website for the pinouts of the chip and compair it to the 68K bus.
Motorola have some nice gateway designs for the Coldfire which should help you with any PPC design.

603e page

basicly i'm trying to figure out how to create a PPC only accelerator card, with other ideas like a miniture PPC card that drops in a 68040/060 socket and pretends to be a stupidly quick 680x0.

Well your going to need a low level PPC emulator (Not like whats included in OS4.0, something that works with just the PPC and some memory) so how good are you at programming?

mainly so you can use your existing accelerators,

Have you seen the Phase5 PPC prototype? A PPC drop in for a standard 68K CPU card.
Its really not the best way to do it though as your going to want an SD-Ram interface and ideally some form of expansion connector to make use of the higher bus speed the PPC can run at.

On a side note to make a PPC only Amiga upgrade you will need to do a few things:

Isolate the PPC from the actual Amiga, normally through transceivers, so you can get the PPC side set up and ready before trying to load the kickstart

you will need memory, you cant access the motherboards memory until you have the 68K emulator online, you cant load the emulator without memory. (The Phase 5 board does it another way, sticking the PPC on the side and using a driver to access the PPC once everything is set up on the Amiga side)

Good luck with any card design.

he 68k bus is not good for running a PPC.. Imagine having a G3 plugged (via an adptor) into a 68K socket... Even if you had a huge amount of L2 SRAM cache on the adaptor it would still be wading through syrup...

Yep, whats the average bus speed of a modern PPC?
its going to be really bogged down accessing the motherboard.
The 603 and 604 chips were slow so a 50mhz bus speed was not really a problem however a modern PPC chip is different.

[Oli_hd]

Hi,

my basic idea was a PPC chip, firmware, northbridge, couple of SODIMM slots, 68k interface logic, and onboard flash ram, or if using G3/4 chip, loading the 680x0 emulation into a protected area of L2 Cache, or onboard flash ram. i'll see if i can get some more info on the amijoe project.

Yep, looks OK to me, the Phase5 card doesnt have a north bridge though, it just has a seperate memory controller (72 pin SIMM as I am sure you know) and it may be an idea to do a similar idea on your card, you can pick up SD-Ram controller chips for the PPC (And 68040-060) supporting up to two Gig of ram (only 75mhz though) which would be very cool.

As for the Amijoe dont forget the Phase5 G3, its what they were working on when they went south, a 68K-less PPC upgrade, you could pre-order it and everything, worth looking up, see if you can get some pictures and attempt to clone it.

but i see where you are comming from with mainboard access... hmmm....

Its not a  big problem, jsut something you have to note.

however, this is more of a hobby project than a "i'm going to go into production and make loadsa money" thing.

Good  ;-)

i'm not looking at using 603/4s, as these just can't cut it running a command emulator as well as their own tasks.

Darn man,  think of all the Cyberstorm owners waiting for OS4  :-D

ok sure you can run your amithlon stuff to kick a 68k's a55, but can you run heretic2? quake2?

Where are those people running Quake 2 on a 68K when you need em hu?

alot of effort has gone into getting these ported, and it'd be a shame to have that wasted... plus there is this OS4 thing....

OS4? whats that then?  ;-)

my main thought is that the cyberstorm/blizzardPPC boards almost seemed to be computers in their own right.

Welcome to the world of computer upgrades, how far can you upgrade a computer before its no longer the original computer?
Your right (Apart from that PCI thing, I see no PCI controller on any PPC card although I know lots of people say the A1200 version has PCI and I could be wrong but....) its been like that for ages though, even some A2000 (030?) CPU cards had graphics card addons, SCSI, expansion ports and memory.

(hail coldfusion! woowoo!   )

lol

i'm not hot on programming, so i'm going to have to see if i can taylor a PPC - 68k interpreter from somewhere.

Why not have a look at Mimic 68K which is a 68K interpreter for the PPC CPU, it only emulates a 68000-68020 from what I can see but you do get the source code so you could just add the extra's if wanted and it only needs 100K of ram.

It looks suitable....

Mimic/68K is a program which allows software written for a 68000, 68010 or 68020 processor to run unchanged on PowerPC and other RISC processors.

Anyway if you get stuck feel free to e-mail me.  :-D

 

Hey Oli, any more news of the Coldfusion project?

Hi, errr, not really, I have to put an order in for some more parts and am going to leave it till after Christmas so I have been doing some more designs based on the current prototype, an A2000 design is done bar the final check, the A1200 design is about 90% done (although it has no upgrades, just the Coldfire and an SO-Dimm) and about 10% in to a CD32 design, sorry. :-(