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-   -   ACA500 plus? (http://eab.abime.net/showthread.php?t=79303)

Shadowfire 21 January 2017 20:16

"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 21 January 2017 21:08

Quote:

Originally Posted by Shadowfire (Post 1136395)
"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 21 January 2017 21:35

Quote:

Originally Posted by appiah4 (Post 1136404)
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 22 January 2017 12:05

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 22 January 2017 12:08

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 24 January 2017 09:35

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 24 January 2017 09:42

Quote:

Originally Posted by appiah4 (Post 1136828)
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 24 January 2017 09:48

Quote:

Originally Posted by demolition (Post 1136830)
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 24 January 2017 09:57

Quote:

Originally Posted by appiah4 (Post 1136832)
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 24 January 2017 10:10

Quote:

Originally Posted by demolition (Post 1136834)
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 24 January 2017 11:06

Quote:

Originally Posted by appiah4 (Post 1136832)
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 24 January 2017 11:49

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 24 January 2017 12:08

Quote:

Originally Posted by Schoenfeld (Post 1136853)
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 24 January 2017 14:07

1 Attachment(s)
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 24 January 2017 20:32

Quote:

Originally Posted by demolition (Post 1136830)
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 24 January 2017 22:46

Quote:

Originally Posted by demolition (Post 1136830)
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 25 January 2017 15:51

Quote:

Originally Posted by appiah4 (Post 1136856)
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 25 January 2017 16:16

Quote:

Originally Posted by idrougge (Post 1137107)
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 25 January 2017 16:41

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

michaelz 25 January 2017 18:55

Quote:

Originally Posted by appiah4 (Post 1137112)
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.


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