ACA500 plus?

[Shadowfire]

"VBR" stands for Vector Base Register. The 68000 originally had its exception address vector pointers hard coded in zero-page memory ($0000xxxx) [If an IRQ came in, the 68000 would change to supervisor mode, dump P and PC on the stack, then fetch the address from these pointers and load it into the PC]. Changing the VBR, changes the location in memory that the 680x0 fetches these pointers from. On the Amiga, this was primarily used to move the pointers out of Chip memory into fast memory, as accessing Chip memory on a faster clocked or 32-bit wide accelerator imposed performance penalties.

[appiah4]

Originally Posted by Shadowfire

"VBR" stands for Vector Base Register. The 68000 originally had its exception address vector pointers hard coded in zero-page memory ($0000xxxx) [If an IRQ came in, the 68000 would change to supervisor mode, dump P and PC on the stack, then fetch the address from these pointers and load it into the PC]. Changing the VBR, changes the location in memory that the 680x0 fetches these pointers from. On the Amiga, this was primarily used to move the pointers out of Chip memory into fast memory, as accessing Chip memory on a faster clocked or 32-bit wide accelerator imposed performance penalties.

Not sure I get it, but I guess it means you can use Fast Mem as Chip Mem?

[Schoenfeld]

Originally Posted by appiah4

Not sure I get it, but I guess it means you can use Fast Mem as Chip Mem?

No, you can never use Fastmem as Chipmem. However, the VBRmove feature lets you move the 68000 vectors from Chipmem to Fastmem, speeding up IRQ handling.

The other positive influence is that software won't be aware of the new location of the vectors. This can be used to slip in your own software, which is what WHDload does: If you press any key, the hardware will trigger an IRQ. The running game will "think" that it sets it's own vector, but in reality, WHDload did it, so WHDload has control over keyboard-IRQs. It can check if it's the quit-key, and react accordingly, without doing too much patching work on the game itself.

Jens

[StingerHU]

Guys, are you using any case for ACA500 Plus? Without any protection it's a bit risky to use. I didn't found any compatible case on the market, yet. Can we expect a case for this great hw?

[demolition]

Not using any case so far. Just being careful and I don't put my coffee cup on it.
There aren't really any components on the top side so not too worried about it being exposed.

[appiah4]

Would the 68000@14Mhz be fast enough to run Linux/m68k? I believe the kernel normally requires at least an 68020 but not sure if that's because of instruction sets or speed..

[demolition]

Originally Posted by appiah4

Would the 68000@14Mhz be fast enough to run Linux/m68k? I believe the kernel normally requires at least an 68020 but not sure if that's because of instruction sets or speed..

The Linux kernel requires MMU which the 68000 does not have and neither does the 020 for that matter. A2500 which was running Amiga Unix had an 68851 MMU besides the 020.

Regarding clock speed, my ACA500p seems to run completely stable @42MHz so it feels quite snappy. Have had it running tests for >4 hours without a hitch.

[appiah4]

Originally Posted by demolition

The Linux kernel requires MMU which the 68000 does not have and neither does the 020 for that matter. A2500 which was running Amiga Unix had an 68851 MMU besides the 020.

Regarding clock speed, my ACA500p seems to run completely stable @42MHz so it feels quite snappy. Have had it running tests for >4 hours without a hitch.

Oh, I see. Bummer. I gues an ACA12xx card would solve that issue I suppose.

As for 42Mhz, wow, I wonder whether you just hit a lucky bin or that's actually what it can usually do.. I'd probably not need more than 14MHz anyway (it'll be mostly a whdload machine for me) but it's good to know

[demolition]

Originally Posted by appiah4

Oh, I see. Bummer. I gues an ACA12xx card would solve that issue I suppose.

I don't think any ACA122x cards have MMUs on them and only some ACA123x models have full 030s with MMU. But even if it does have an MMU, that doesn't mean you can run Unix on it unless it is built specifically for that MMU model.

[appiah4]

Originally Posted by demolition

I don't think any ACA122x cards have MMUs on them and only some ACA123x models have full 030s with MMU. But even if it does have an MMU, that doesn't mean you can run Unix on it unless it is built specifically for that MMU model.

There goes that idea

[liviux76]

Originally Posted by appiah4

As for 42Mhz, wow, I wonder whether you just hit a lucky bin or that's actually what it can usually do.. I'd probably not need more than 14MHz anyway (it'll be mostly a whdload machine for me) but it's good to know

I haven't used it for more than a few consecutive hours but it seems to me very stable as well.

[Schoenfeld]

There's M68k Linux and BSD for the Amiga, both support the 68030 MMU. However, any Unix-like OS is pretty useless without network, and that's still on the agenda for the ACA500 and ACA500plus. I have no idea when I can start with that.

Jens

[appiah4]

Originally Posted by Schoenfeld

There's M68k Linux and BSD for the Amiga, both support the 68030 MMU. However, any Unix-like OS is pretty useless without network, and that's still on the agenda for the ACA500 and ACA500plus. I have no idea when I can start with that.

Jens

I for one would love to see development on this front An expansion to the ACA500plus that would let me install linux on it and join a tcp/ip home network would be super awesome.

[E-Penguin]

The plipbox is perfectly usable, if slow. There aren't the drivers for it in linux though.

Speaking of networking, I got my A500 + ACA500plus + plipbox online last night. A small victory, perhaps, but something I've been wanting to do for years.

[nogginthenog]

Originally Posted by demolition

The Linux kernel requires MMU which the 68000 does not have and neither does the 020 for that matter.

Technically it doesn't. There's uClinux. I think the changes were merged with the base kernel but I could be wrong.

[remowilliams]

Originally Posted by demolition

Regarding clock speed, my ACA500p seems to run completely stable @42MHz so it feels quite snappy. Have had it running tests for >4 hours without a hitch.

Mine seems to get on well with 42Mhz so far too

Attaching the ACA1233 is causing some weird intermittent shenanigans though like odd crashes, memory going suddenly missing (like 128M of it), slow CF disk speeds and needing hard power resets.

Also noticed this weirdness too - WHDLoad doesn't seem to 'run' the first time it's started... ?

http://www.a1k.org/forum/showpost.ph...&postcount=577

I'm using a custom heavy duty Carlsen C128/Amiga power supply by the way, and Menu system V0.79, WHDLoad 18.3

[idrougge]

Originally Posted by appiah4

I for one would love to see development on this front An expansion to the ACA500plus that would let me install linux on it and join a tcp/ip home network would be super awesome.

You certainly don't need Linux to join a TCP/IP network.

[appiah4]

Originally Posted by idrougge

You certainly don't need Linux to join a TCP/IP network.

No but I know linux and wouldnt mind using it because it has MUCH better networking than AOS.

[idrougge]

AmigaOS's networking is basically the BSD network stack. You'll feel right at home with AmiTCP.

[michaelz]

Originally Posted by appiah4

No but I know linux and wouldnt mind using it because it has MUCH better networking than AOS.

Just curious; why "bother" with amiga's at all? I love them, with workbench and all. I use Linux and Windows on my x86's, but see no added value on an Amiga for Linux.