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PostPosted: Fri Sep 13, 2019 5:17 pm 
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Location: Poland
I got Gimmick 2 hack which was done using INL-XO-ROM PCB. My version does not have expansion sound, but the PCB at first glance looks like super-dooper:
* place for PRG1-ROM (up to 8MB), PRG2-ROM (up to 512 kB) - was PRG1 meant to be for storing games and PRG2 for firmware when using micro sd card?),
* place for CHR-ROM (up to 512 kB),
* place for PRG/CHR-RAM (even up to 128kB),
* place for battery,
* place for AY-3-8910,
* place for micro sd card,
* some other stuff (logic to support MMC2/MMC4) and a few unpopulated chips.
Probably one universal board for many applications.

Luckily I have a lot of AY-3-8910 chips so I reverse engineered the board mainly because I was curious which components need to be soldered to make audio expansion work.

* The board is build using LAMXO256 CPLD. Does not seem to be very popular, nor cheap (2$) but with similar capacity (256 LUT) and I/Os (78) versus Altera EPM240 (1$, 240 macrocells, 80 IO pins)
* 16 channel 74LVC16245 buffers used for 3V3-5V translation (4$) - I prefer 8 channel 74LVC245 (0.1$), smaller and easier to route signals. And they still ran out of the pins and needed to translate PPU-A13/PPU-A12 using resistor divider
* CON1: There is place for micro SD - loading games like in everdrive?
* IC10: There is place for SPI memory (probably for Dragon Ball and other games that require SPI flash for storing savestates)
* IC9 (STM32F0, unpopulated) / IC13 (STMSTM8S003F3P6) - seems to be responsible for CIC stun. It also has access to micro SD card pins and audio output - was this meant to be used to play back music from sd card and output it to NES?
* Programming CPLD done via EXP0 (TDO) / EXP1 (TDI) / EXP2 (TMS) / EXP3 (TCK) headers
* There is a jumper which selects if WRAM-A12 is tied to CPU-A12 or driven by CPLD (PRG-ROM-A12 is driven by the same pin) - 4kB banking support, woah, can be used to play NSF
* JP3 - unpopulated 5 pin small connector (was it for external audio hook-up?)

Flaws:
* The right terminal of battery (negative) is not routed to anything,
* One of the chasis pins of micro sd card is not routed to anything,
* One leg of R4 is not routed to anything,
* CPLD directly sees PPU A10-A13, but for MMC2/MMC4 it also needs to check if PPU A3-A9 are all ones (and so they used NAND - clever, I did similar trick but using diodes). Weird thing is that they do not care for PPU A0..A2 (according to wiki - MMC2 latch 0 responds only to one address)
* CPLD controls output enable of IC8 buffer and 1/2 of IC7 buffer using the same control line. For IC8 this is strange cause this buffer converts CPU address line which should be always enabled.

Image Image Image Image Image Image Image


Last edited by krzysiobal on Fri Sep 13, 2019 10:38 pm, edited 1 time in total.

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PostPosted: Fri Sep 13, 2019 9:11 pm 
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Joined: Mon Sep 20, 2004 6:04 am
Posts: 3737
Location: Indianapolis
That type of coin-cell holder is a clip that presses the battery directly against the gold on the board. So the solder terminals are both +.

That's a pretty cool write-up on that board.


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PostPosted: Sat Sep 14, 2019 2:53 pm 
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Joined: Sun Apr 13, 2008 11:12 am
Posts: 8613
Location: Seattle
krzysiobal wrote:
* The board is build using LAMXO256 CPLD. Does not seem to be very popular, nor cheap (2$) but with similar capacity (256 LUT) and I/Os (78) versus Altera EPM240 (1$, 240 macrocells, 80 IO pins)
Right now, I cannot find the EPM240 for anything near that good of a price in the US.
krzysiobal wrote:
* 16 channel 74LVC16245 buffers used for 3V3-5V translation (4$)
Prices in the US are much more favorable for the 74LVC16245; I'm seeing around ~0.3$ per for both the 16-signal and the 8-signal part.
Quote:
* IC9 (STM32F0, unpopulated) / IC13 (STMSTM8S003F3P6) - seems to be responsible for CIC stun. It also has access to micro SD card pins and audio output - was this meant to be used to play back music from sd card and output it to NES?
Not a stunner! A full function CIC. INL's talked about it a bit.

Quote:
(according to wiki - MMC2 latch 0 responds only to one address)
True, but irrelevant; Punch-out doesn't seem to use this behavior.


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