zik@bruce.cs.monash.OZ.AU (Michael Saleeba) (01/03/91)
I'm in the process of developing a new operating system on my 2000, and I'd
really like to make the most of my Amiga's hardware to do this. What I'd
really like is to be able to run AmigaOS on the 68000, but set the 68020
running also. My approach would be to run my new OS in the 4Mb of 32 bit RAM
local to the A2620, and try to communicate with the 68k using message
passing and semaphores.
The advantage of this to me is that I would have a fully-fledged OS to
develop my own OS on, and I'd be able to test it without continually
crashing the system and having to reboot. Also, I'd be able to use the
existing features of AmigaOS like windowing and so on as I/O devices
without having to write my own, and without having to waste `020 CPU
time!
Sounds neat, but will it work? What I'd really like is for someone to tell
me that all I need to do to set both processors running concurrently is
to manipulate autoconfig device x or location y. I'm not a registered
developer, although not for lack of trying (Commodore Australia doesn't
believe that there are any _real_ developers in Australia!). Can anyone
help me with this hack?
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Michael Saleeba - sortof postgraduate student - Monash University - Australia
"Why is it that the people who like fast computers also like fast cars?"daveh@cbmvax.commodore.com (Dave Haynie) (01/04/91)
In article <3528@bruce.cs.monash.OZ.AU> zik@bruce.cs.monash.OZ.AU (Michael Saleeba) writes: >What I'd >really like is to be able to run AmigaOS on the 68000, but set the 68020 >running also. My approach would be to run my new OS in the 4Mb of 32 bit RAM >local to the A2620, and try to communicate with the 68k using message >passing and semaphores. [...] >Sounds neat, but will it work? What I'd really like is for someone to tell >me that all I need to do to set both processors running concurrently is >to manipulate autoconfig device x or location y. Unfortunately, that won't work, at least not without hacking the A2620. The A2620 grabs the A2000 bus when the machine first powers up. If you select 68000 mode via the A2620 ROM menu, what really happens is that a bit in a special configuration register gets set. This bit gets the 68020 out of the way by forcing the whole A2620 board into reset. It certainly could have been done in a way that would have allowed both CPUs to run at once. However, the guy who was originally working on the A2620 never considered that, or never considered it useful. When I took over, I put in the "get the 68000 back" mechanism, but it was too late in the project to go mucking much with the design. We were far more concerned with making the A2620 work, period, than adding any features. It just turned out that the 68000 mode, the way I did it, was practically for free, and took only a few minutes to come up with. > Michael Saleeba - sortof postgraduate student - Monash University - Australia > "Why is it that the people who like fast computers also like fast cars?" And coffee. Speed is addictive, in its many forms... -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy "Don't worry, 'bout a thing. 'Cause every little thing, gonna be alright" -Bob Marley