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Author Topic: Arcade game "1943 : the battle of midway" running on an FPGA!  (Read 10084 times)

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Offline Illuwatar

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Re: Arcade game "1943 : the battle of midway" running on an FPGA!
« on: September 15, 2008, 01:27:13 PM »
The only difference between IS64WV51216 and IS62WV51216 used in MiniMig is the numbering order of the address lines. Power, data and control lines are all in the same place.
 

Offline Illuwatar

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Re: Arcade game "1943 : the battle of midway" running on an FPGA!
« Reply #1 on: September 15, 2008, 06:47:44 PM »
I don't think the address line order actually matters in this case. Yes - you will end up, reading a different memory cell compared to the correct RAM type, but you will always end up at the same cell. SRAM does not care about order as long as you are inside the address range.

But the price and availability is an other issue... :-(


Edit: IS61WV51216 and IS64WV51216 do have the same pin layout (they share the same data sheet too), so you have the address line renumbering issue in both. If there were sockets for 44-TSOPII, then this would be a simple issue to test (or if someone have some professional resoldering station that removes SMD without damaging the PCB).
 

Offline Illuwatar

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Re: Arcade game "1943 : the battle of midway" running on an FPGA!
« Reply #2 on: September 16, 2008, 11:38:42 AM »
The largest Spartan 3 in QFP208 (that package used for MiniMig) is the 3E with 500k gates. Going bigger means BGA that is impossible to solder for most DIY freaks here...

If the BGA issue could be solved in some way, then there are not a big deal to create a larger MiniMig that could be code compatible (almost) with the original design - and in the same moment, add more RAM and a better video-DAC for 24bit graphics. The PCB itself needs to be at least 4-layer when using BGAs, but that is more a cost issue than a design problem.
 

Offline Illuwatar

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Re: Arcade game "1943 : the battle of midway" running on an FPGA!
« Reply #3 on: September 17, 2008, 09:33:22 PM »
That's true - the 3E series and the 3 series are not direct replaceable. You need a new PCB design for that 100k gates extra. I have been working on a design like this - I have a partial drawing of a MiniMig with 8 MB SRAM using this Spartan 3E. But the difference in hardware requires a recompiled MiniMig core too. For these arcade classics, changing the FPGA seems to be a non-issue. But is it worth the work in creating a new PCB that uses the Spartan 3E for just 100 000 gates more? At least the memory could be counted for (replace the 512k x 16 with 1M x 16, 10ns)...