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View topic - Super rare 1 leg cap game PCB

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  • Joined: 27 Jun 2020
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Super rare 1 leg cap game PCB
Post Posted: Fri Jun 25, 2021 12:08 pm
This is a super rare copy of golden axe that's belonged to my partner since she was a kid.

I guess it's origin is New Zealand (we are in aussie)

The mapper has a special limited edition single leg capacitor

sloppy bastards

Pretty much opening every game I have and checking our double ups to swap over hoping for a game with a mapper - originally hoping for one like from "the ninja" but other copies were all integrated. I did have a faulty copy of the ninja with separate mapper but it seems to be faulty beyond repair (or not worth the time right now)

Now I don't want to waste this on a 128kb game when it can address a full 512kb!

PS: it took some persuading for her to let me swap an integrated mapper copy for her childhood one separate mapper one (which she didn't even know about until she saw me rampaging through carts with a screw driver)

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  • Joined: 27 Jun 2020
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Post Posted: Fri Jun 25, 2021 12:49 pm
While we're at it

does anyone know where to find the pinouts for these 32pin game ROMS?
I assumed it would match with my M27C4001, as the M27C256/512 matches the 32kb games.

It' going to need some leg lifting and jumpers

thanks

**All good, it looks like previously people have used this chip here:

http://web.archive.org/web/20141210222820/http://cgfm2.emuviews.com/smsflash.php

AM29FO / switch Pin 1 and 31

For the M27C4001 it's a direct drop in, but strangely enough you need to pull the programming pin to the same level as VCC, so you just run a straight horizontal (or vertical or what ever) bridge from Pin 32 to Pin 1 (pin 32 is effectively "floating" on the PCB).

I finally "have streets of rage II"
Outrageously priced games like this and Home alone are why I'll never own the complete collection.
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  • Joined: 14 Aug 2000
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  • Location: Adelaide, Australia
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Super rare 1 leg cap game PCB
Post Posted: Sun Jun 27, 2021 8:11 am
What woman is a keeper.

That's because some EPROMs care about the state of the Vpp pin when not in programming mode and disable the data outputs, while others do not. The datasheet will tell you.

From memory there info on the mappers and replacing the PROM in the SMSPower Development section, but here's the pinout from my R-Type cartridge (512KB) with mapper that I have on me after posting the other ROM pinouts the other day.

     -------o------
 NC |  1        32 | Vcc
A16 |  2        31 | A18
A15 |  3        30 | A17
A12 |  4        29 | A14
 A7 |  5        28 | A13
 A6 |  6        27 | A8
 A5 |  7        26 | A9
 A4 |  8        25 | A11
 A3 |  9        24 | /OE
 A2 | 10        23 | A10
 A1 | 11        22 | /CE (tied to gnd)
 A0 | 12        21 | D7
 D0 | 13        20 | D6
 D1 | 14        19 | D5
 D2 | 15        18 | D4
GND | 16        17 | D3
     --------------
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Post Posted: Sun Jun 27, 2021 1:04 pm
Yep! exact match with M27C4001 and because pin 1 is floating on the PCB (it's soldered in but has no traces to it) you just jump 32 across to it as per data sheet it enables read mode.

I also randomly decided to do what I did when dumping the first 32kb of Ghost Busters which matched the first 32kb of the good dump... went through every 4mbit 32pin DIP on XGpro

NEC UPD27C4001

This gives a pin error on pin 1 (the programming pin) but otherwise dumped a 100% match to a known good dump of Golden Axe...

Still baffles me after 30+ years no one has figured out the inner secrets of both the internal/ external mapper. Going to have a hell of a hard time squeezing in heavydecks (neonman) latest and least component heavy mapper revision.

Also made this morning! the grids verticals were regrettably guessed, the horizontals match the original. (well they're both out, but it's close enough)

**Also went on a rampage messaging cartridge sellers to open their carts up to see if they had separate mappers lol. I had one response - but he just wanted to know why on earth there was a difference.
SORII_SMS.jpg (751.74 KB)
SORII_SMS.jpg

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