Assembled Minimig v1.1, larger FPGA (BGA-package)

[Hans_]

Seeing as you're making it nano-itx size, you might want to have a look if there are any standard nano-itx connector layouts you could use. With mini-itx there are standard layouts (or at least a standard backplate area that you can use). If you do go completely the pin header route, please use the standard pin header layouts for things such as the serial port; it'll make connecting them up so much easier.

Hans

[Hans_]

McVenco wrote:

ThomasML wrote:

but I think most people would want a fully assembled board.

How very true. Although there are quite some people who are not really afraid to do some basic soldering, I think the majority is pretty much "solderingly challenged" (just like me).

Soldering a BGA isn't some basic soldering. AFAIK, it's impossible to do with a soldering iron; you need the right equipment to do it.

Hans

[Hans_]

koaftder wrote:

alexh wrote:
You cannot solder a BGA with a soldering iron, you need reflow oven. Prices start at about £150 and go up.

Or you could reflow in a nice toaster oven, but thats for us hackjobs (:

Which is the technique that I'd use, if I had an oven set up for it. I'd be interested to hear of any "hackjob" method of verifying that all the solder balls are correctly soldered; you can't exactly inspect them visually.

@ThomasML
Are you considering putting a proper 24-bit RGB DAC on the board for video? I'd definitely be interested in the board if it included that. Such a feature would provide make adding AGA support a possibility. That would mean a certain amount of extra work though.

EDIT: Adding 24-bit RGB would be pointless without a 68020+ processor, so it's probably too much work for now, particularly as you're using the v1.1 schematics.

Hans

[Hans_]

freqmax wrote:
@Hans_:
Why is 68020+ needed for 24bit RGB?, dram speed have improved speed since Amiga
days, if that's the bottleneck.

Not needed, but AGA is 32-bit and the 68000 has a 16-bit external bus.

Hans

[Hans_]

freqmax wrote:
@Hans_:
Maybe I should ask like this, is it due memory bus speed or some other issue that a 32-bit bus is needed?

Basically all AGA software was designed for a machine with a 32-bit bus and a minimum 68EC020 processor running at ~28MHz. A 16-bit bus means half the memory bandwidth, and a slower processor will just make things worse. I'd expect most AGA games to fail to work properly on anything less than the basic A1200 specs.

Hans

[Hans_]

@freqmax

freqmax wrote:
@Hans_:
The memory bandwidth of Minimig is artificially throttled (according to Dennis). So it should be possible to use the full bandwidth of the ram to feed the AGA graphics.

It's the bandwidth between the CPU and the chipset that's the problem, not the chipset and memory. The timing of the CPU's bus is limited by the CPU. You could get the AGA chipset working, but performance would be substandard because the CPU is slow and it's memory bandwidth too limited.

Hans