Minimig worthwhile?

[boing4000]

Take your time in soldering those RAM chips Darrin. Its of course possible but require a quiet hand and suitable equipment like: 0.7mm fine solder, desoldering braid (and if available solder flux). Also the upper RAM chips has to match pin grid accurately, else its hard to solder a stable contact.

If there is any problem, Im sure Jakub or I can help to make your BigMem-Minimig run :-)

[Darrin]

boing4000 wrote:
Take your time in soldering those RAM chips Darrin. Its of course possible but require a quiet hand and suitable equipment like: 0.7mm fine solder, desoldering braid (and if available solder flux). Also the upper RAM chips has to match pin grid accurately, else its hard to solder a stable contact.

If there is any problem, Im sure Jakub or I can help to make your BigMem-Minimig run :-)

Cheers for the advice.  Jakub sent me a guide and some pics.  I've got the fine solder, desoldering braid and plenty of beer to calm my nerves.  I just need to find some gel flux.

If I can manage to do this then anybody should.  :-)

[wolfchild]

Hey,

I've also got a couple of extra RAMs, bought with the intent of upgrading the memory.

Any advice on how to do so?  Do I have to straighten the tip of each pin?

Cheers!
Edwin

[Darrin]

wolfchild wrote:
Hey,

I've also got a couple of extra RAMs, bought with the intent of upgrading the memory.

Any advice on how to do so?  Do I have to straighten the tip of each pin?

Cheers!
Edwin

Use a set of pliers with FLAT blades (not crimped for gripping) to squeeze the legs of the chips flat otherwise they wont reach the legs of the chips already on the board.  

Don't forget that one leg of each new RAM chip doesn't get soldered to the lower RAM block, but it connected by wire to the spare I/O pins.

[wolfchild]

Thanks Darrin!

I need to buy me some desoldering wick and give it a try.  I think the chip select pins should be connected to the IO ports, right?

There is a photo from Jakub of the mod on minimig.net.  Will make sure to study it closely before putting any tools to them chips and board

Edwin

[boing4000]

Right, each pin #6 is not to bend. This modification will only work in new core release. Currently the extra ChipEnable lines should not be connected to spare IO pin, it could cause unwanted trouble.

It would be best to use removeable connection at spare IO due to some alternative FPGA core on Minimig pcb. FPGA64 and VIC20 core uses spare IO for Floppy IEC bus connection, This could interfere if suddenly some RAM enable went to low and cause a bus conflict.

[Darrin]

boing4000 wrote:
Right, each pin #6 is not to bend. This modification will only work in new core release. Currently the extra ChipEnable lines should not be connected to spare IO pin, it could cause unwanted trouble.

It would be best to use removeable connection at spare IO due to some alternative FPGA core on Minimig pcb. FPGA64 and VIC20 core uses spare IO for Floppy IEC bus connection, This could interfere if suddenly some RAM enable went to low and cause a bus conflict.

However, in my case with the ARM expansion the lines do need to be connected to the I/O pins.

It might be an idea not to do the mod if your planning to buy an ARM board until you fit it as unsoldering and bending pins after they have been soldered in place might cause problems.

[kolla]

Huh, RAM upgrade? How much RAM is the result?

[Darrin]

kolla wrote:
Huh, RAM upgrade? How much RAM is the result?

It adds another 2MB to the board to give 3.5MB total which is enough to use WHDload with the 28MHz 68000 and the Hard File for playing games from Workbench (assuming you don't want to load them from the ADFs).

The C-One Minimig core actually gives you 8MB of RAM.

[kolla]

Darrin wrote:

kolla wrote:
Huh, RAM upgrade? How much RAM is the result?

It adds another 2MB to the board to give 3.5MB total which is enough to use WHDload with the 28MHz 68000 and the Hard File for playing games from Workbench (assuming you don't want to load them from the ADFs).

Interesting - any reason why up to 8 MB is not possible on Minimig as well?

Btw - why havent I seen anything about this on www.minimig.net ? :-)