Minimig Review completed!

[TheDaddy]

When you say that all the Kickstarts work, do you mean 2.04,3.0 and 3.1 by renaming them to KICK.ROM?

Also have you tried the failing games with other versions of Kickstart other than 1.3? For example 2.04?

 :-)

[freqmax]

I do not have access to any Minimig. So it's a compilation of what's available from other sources.
Minimig will load whatever is in the file 'KICK.ROM' and expect it to be of 512 kByte size no matter what. And use it as kickstart.

I don't know which kickstart that was used to run the games.

[CD32Freak]

My personal opinion is that the power supply part should have an onboard +5V regulator.

@freqmax
Illuwatar has implemented an internal, switched regulator on his mini-ITX Minimig. We could also use the other great improvements he made like S-Video and Composite video outputs, buffered audio and a larger PIC :-D

[freqmax]

An onboard linear regulator is easy to accomplish. A switched solution is more complicated and costly.
S-Video/Composite will complicate and add cost.
Unless the current MCU is too small for floppy write capability and HDD emulation. I don't see the need.

Designing a new board, a switch solution can be tricky due EMI interference.

[ptek]

Be carefull with the static electricity of your hands! Don't touch the board components and get a case as soon as possible... You've been lucky.

[amazing]

it doesnt matter what kickrom u use as long as u rename it into kick.rom

[HenryCase]

freqmax wrote:
The FPGA can't turn itself off in the current design. But it would be possible to snoop the keyboard. And make the MCU forcefully reload the FPGA and let the FPGA clear the memory on boot.

Doesn't the PIC load before the FPGA does? If it does, you could have a 'standby' mode when the power supply is plugged in, right? Don't know if it would do much to protect the circuitry, but it might have some benefit.

freqmax wrote:
The MCU (PIC18) could be updated by makeing a small circuit board that stack an ICSP connector + MCU socket. And then use that to wire to a programmer. The next minimig board maybe should have an onboard ICSP connector.
(ICSP - In circuit connector for programming)

Are the pins used to program the PIC connected to the FPGA? If so, wouldn't it be possible to use a customised FPGA core to reprogram the PIC?

[TheDaddy]

Well...I have tried renaming kickstart 2.04 and 3.0 to KICK.ROM and all I get is a red screen and nothing else.

It seems only to work with 1.3 (512K).

I was going to test the failing games with 2.04 but it won't boot (just red screen). :-?

[Protek]

TheDaddy wrote:
Well...I have tried renaming kickstart 2.04 and 3.0 to KICK.ROM and all I get is a red screen and nothing else.

It seems only to work with 1.3 (512K).

I was going to test the failing games with 2.04 but it won't boot (just red screen). :-?

Are those ROM images from an A500? I think you need to extract the image from a ROM that is meant specifically for an A500. At least there is an A500 variation of the 3.1 ROM available.

Have you tried putting WB in an ADF and tried loading that?

[TheDaddy]

>>Are those ROM images from an A500?

Yes, I have also used the ones from my Amiga Forever cd.

The 2.04 is the one from an A500 Plus.

>>I think you need to extract the image from a ROM that is meant specifically for an A500. At least there is an A500 variation of the 3.1 ROM available.

>>Have you tried putting WB in an ADF and tried loading that?

That is my next step, I need to find my WB 1.3 disks...
 :-)

[TobiFlex]

TheDaddy wrote:
Well...I have tried renaming kickstart 2.04 and 3.0 to KICK.ROM and all I get is a red screen and nothing else.

It seems only to work with 1.3 (512K).

I was going to test the failing games with 2.04 but it won't boot (just red screen). :-?

RedskullDC has done his tests with the minimigtg68:
minimigtg68

I have never seen a picture from a minimig with a 2.04 bootscreen. But the minimigtg68 can boot all versions of kickstartrom.

Now I found a little but important difference in the 68sec000 and the TG68 IP Core.

The tg68 is a 68000 Clone. But the 68sec000 insn't a 68000 and isn't a 68010. That is the Problem.

The Move from SR is priviligated in the 68sec000. Kick >= 2.04 use this Instruction to check the CPU Type.
For the kick 2.04 is the 68sec000 a 68010. But the 68sec000 has the exception stack frames from the 68000. That can't work without a patch.

But the TG68 use the Move from sr in user state and use also the 68000 exception stack frames. That works fine.

I think the TG68 IP Core is the better choose for the minimig!

Viele Grüße
TobiFlex - the creator of the TG68 Core ;-)

PS: any infos about Kick 3.1 - is there the 68sec000 known???
 

[straycat]

HenryCase wrote:
I would imagine you'd need the multi-ADF support to do this, which Dennis is working on. Workbench runs so that's one part of the equation sorted. Currently the memory card is read only (so you couldn't save work you did), but there isn't any reason (AFAIK) why writing to the memory card couldn't be added to the current design.

Going by this am I right to assume you cannot save your game position on the Minimig yet?

[neuroflip]

HenryCase wrote:
Currently the memory card is read only (so you couldn't save work you did), but there isn't any reason (AFAIK) why writing to the memory card couldn't be added to the current design.

what implies to upgrade to this feature?
reprograming the pic and/or change the .bin file?

if i am an unexperienced user..., what will be the dificult to do this?

[Dennis]

But the 68sec000 insn't a 68000 and isn't a 68010. That is the Problem

Exactly.
Afaik, all roms recognize the MC68SEC000 incorrectly.
What the kickstart code does is the following
(this is the disassembled kickstart 1.2 code by Markus Wandel):

FC03E2  move.w    $0128(A6),D0      See if we are running on a 68010/020.
FC03E6  btst      #0,D0
FC03EA  beq.s     FC041E            Skip the following if not.

        ; Special initialization for machines using a 68010/020.

FC03EC  lea       FC087C(PC),A0     Point at 68010/020 bus error handler.
FC03F0  move.w    #8,A1
FC03F4  move.l    A0,(A1)+          Fix the bus error vector.
FC03F6  move.l    A0,(A1)+          Fix the address error vector.

FC03F8  move.l    #$FC08BA,-$1C(A6)     Use a different Supervisor() routine.

        ; Fix GetCC() for 68010/020 processors.

        ; We simply load the instruction sequence "MOVE.W CCR,D0 / RTS" into
        ; the place where the library jump vector to GetCC() normally is.

FC0400  move.l    #$42C04E75,-$0210(A6)

I think the "move.w $0128(A6),D0" is wrongly disassembled and should actually be the Move from SR instruction. As this instruction is priviliged the code for 68010/68020 will be executed. The bus error and address error vectors are patched; no problem for the Minimig as these are not generated. The GetCC() is also (wrongly) patched. This is a problem for the Minimig. Luckily, this function is only used very rarely so Kickstart 2.04 (V37.175 tested here) runs fine on the MC68SEC000, as does kickstart 3.1.

Dennis

[HenryCase]

straycat wrote:

HenryCase wrote:
I would imagine you'd need the multi-ADF support to do this, which Dennis is working on. Workbench runs so that's one part of the equation sorted. Currently the memory card is read only (so you couldn't save work you did), but there isn't any reason (AFAIK) why writing to the memory card couldn't be added to the current design.

Going by this am I right to assume you cannot save your game position on the Minimig yet?

Correct. The hardware can do it, but the PIC+FPGA code don't allow it yet. I imagine this will be a feature that is added early on, so I wouldn't let it worry you too much.

neuroflip wrote:

HenryCase wrote:
Currently the memory card is read only (so you couldn't save work you did), but there isn't any reason (AFAIK) why writing to the memory card couldn't be added to the current design.

what implies to upgrade to this feature?
reprograming the pic and/or change the .bin file?

if i am an unexperienced user..., what will be the dificult to do this?

Good questions neuroflip.

There are two programmable elements in Minimig v1.1, the FPGA chip which houses the OCS chipset recreation and the PIC chip which helps to boot the system and controls memory card access (AFAIK).

When updates for Minimig are available, upgrading the FPGA is very easy. All you would need to do is change the .bin file on the memory card.

Upgrading the PIC is slightly different. At the moment, it would involve taking the chip and putting it in a PIC programmer. PIC programmers are fairly cheap to make or buy. However, there might be an easier solution, which would let the Minimig update its own PIC through a .bin file, which would make updating the PIC as easy as updating the FPGA (I asked freqmax earlier to see if this would be possible, but if anyone can answer my question please do so).

[freqmax]

I think it's possible to make the FPGA update the PIC, provided that the MCLR and some other pins can be used for this.
However, there's currenly hardly ANY i/o pins available. I would suggest to use a XC3S500-PQ208 for the next version.