Wishing for mainboard with new component layout for A1200

[AJCopland]

Part of the issue with USB are that you need a CPU side USB stack/driver to control the peripherals that you plug into it and that it actually takes a bit of processing power to do run that. There are already USB stacks for the Amiga though so it must be workable.

For building a "power minimig" or "MiniMigV2" etc the 68060 makes more sense from a simplicity point of view. This is because the 060 is a 3.3v part whilst the 020, 030 and 040s are all 5v parts. The rest of the MiniMig (FPGA, RAM et al) is all 3.3v so attaching them will require voltage level shifting and different power planes for the two voltage regions on the board which makes it all more complicated and a lengthier process to build.

Of course the 68060 is harder to get hold of and more expensive...

Andy

[alexh]

arnljot wrote:
as a user I must disagree on this one. Just a mouse and keyboard alone almost justifies this one to me

But they dont work!!

Workbench yes... Games No. (Well mainly no)

You see the games hit the hardware registers of the custom chips. They do not go via the OS and so (AFAIK) do not work with USB keyboard and mice.

Most USB mice and keyboards support legacy PS/2 over USB so with an adapter you can use them directly with MiniMig via the PS/2 ports which are wired to the hardware of the custom chips.

arnljot wrote:
and then add mass storage and it´s perfectly clear to me that this is a very important feature.

You get mass storage via IDE, replicate the GAYLE registers and you have a 100% compatible interface AND drivers.

arnljot wrote:
slightly off topic:
It seems that the 68040 are abundant, in speeds 25mhz, 33mhz and 40mhz. Would it be a suitable choice for a "power minimig"? Which one of the 68 series is most common, except for the 68000?

It has to be 3.3v I/O to interface to the FPGA. This limits which 68k you can use. You cannot use any 040 from the Amiga days. Not without extra electronics to convert the I/O levels. You cannot even use a regular 68000 out of an A500! (MiniMig uses a special 3.3v I/O 68000)

As I have said before the 68060 is NOT 3.3v I/O (unless the specs at Freescale are wrong). It is 3.3v core, 5v I/O.

[arnljot]

@alexh
Yup, I know about PS2 and USB and that most peripherals include chips that operate on both.

And perhaps it's over engineering to map usb->ps2->amiga inside the minimig. And also allow a usb stack to access the usb ports... But:

Yes, it takes CPU to run a USB stack, but it can be done on the Amiga1000, and on OS classic with Poseidon. So it should be doable on the Minimig, but certainly hardly usable with a 7mhz 68000.

And yes, IDE will give us mass storage. But how cool would it not be to be able to boot of a memstick which you also use at work with WinUAE? Hmm...

Any way, if the SD card could be used as a IDE drive, I'd be happy as a clam

When it comes to form factor and the A1200 plastics, I'm sure a 17x17cm Minimig will fit

[AJCopland]

alexh wrote:
As I have said before the 68060 is NOT 3.3v I/O (unless the specs at Freescale are wrong). It is 3.3v core, 5v I/O.

Ah bugger, I must have missed that, sorry.

Andy

[alexh]

I'm unsure... some of the Freescale documentation says 5v I/O in some places and 3.3v I/O in other places.

I'm wondering if it does both?

[alexh]

arnljot wrote:
But how cool would it not be to be able to boot of a memstick which you also use at work with WinUAE? Hmm...

I already do it now using A4000 and a CF card (which is IDE).

[bloodline]

alexh wrote:
I'm unsure... some of the Freescale documentation says 5v I/O in some places and 3.3v I/O in other places.

I'm wondering if it does both?

If the 060 doesn't drive the I/O at 5v, the 68k support devices that it needs to interface with wouldn't work!?

[alexh]

Not if it is just digital. You should look up TTL thresholds. 3.3v is still a HIGH.

[bloodline]

alexh wrote:
Not if it is just digital. You should look up TTL thresholds. 3.3v is still a HIGH.

So the the 060 could happily run at 3.3v and simply tolerate 5v inputs...

[alexh]

bloodline wrote:
So the the 060 could happily run at 3.3v and simply tolerate 5v inputs...

Maybe, I think it is more complicated than that. It probably requires voltages on certain pins at certain times...

[uncharted]

I can't believe that this has hit two pages, and no-one has mentioned ColdFire yet :-D

[AJCopland]

It's like the amiga communities variant of Godwin's Law :-o

Andy

EDIT: damned non-html links blah blah blah .. nazis

[AJCopland]

I suppose an obvious question would be how do the Blizzard card handle it? You can swap out the 040 for an 060 and you change the voltage regulator. Does that regulator change the voltage going just to the core or to the IO as well via level changers?

Andy

[arnljot]

Maybe Dimlow of EAB will donate his Apollo1240/60 regulator design to the Minimig?

Could it be done with out too much redesign to theMinimig hardware and firmware?

[alexh]

Eh?? That is just a remake of a standard voltage regulator board for an Apollo card. An ultra simple board which has been on sale for years, that PG has been selling to people on this board for years.

All the "good bits" (if there are any) are actually in the 1240/1260 board design itself, not this addon.

The MiniMig PCB would require a full re-design to use an 060 CPU. MiniMig is a two layer PCB which would almost certainly not be possible for an 060 design due to the number of power and ground pins there are compared to a 68000

Not to mention that MiniMig is a 16-bit design and the 68000 is a 32-bit processor, there are not enough pins on the FPGA that MiniMig uses for a 32-bit processor so you'd have to change to a different FPGA too.

And 1.5Mbytes of RAM is not enough ;-)

[arnljot]

@alexh
Just goes to show how little I understand about hardware

MiniMig is twolayer, so much I've caught on. But are you saying that BLizzard, Cyberstorm and Apollo 060 cards are singlelayer, or much more (4++)?

What would these "good bits" of such a card be? The basic good bits that is, baring the interfacing with the Amiga side.