Porchy

Testing Bubble Bobble ROM banks with Fluke 9010

Guides Comments Off

Nov 012014

Recently I was talking to IronGiant about testing the “a78-05-1.52” ROM on an original Bubble Bobble PCB with the Fluke 9010.
As the ROM is banked we cannot test this ROM in one go.
Here is how we managed to do it.

0) Before we do anything we need to disable the watchdog otherwise this wont work properly. This is done by cutting the track on JP6 on the solder side (thanks to IronGiant for the info).

1) Take the ROM dump for “a78-05-1.52” and split it into 4 files using a HEX editor or similar. Each file should be 0x4000 bytes in size.
Run all 4 files through one of the signature calculators that can be found online and make a note of them.

2) The bankswitch lies at address 0xFB40 in the address map.
You need to write a value between 4 and 7 to select the relevant bank.
So start by writing 4 to address 0xFB40.

3) Next we need run a ROM check on between address 0x8000 & 0xBFFF.
This signature should match the first 0x4000 bytes of the ROM.

4) Repeat steps 2 and 3 a further three times incrementing the value written to address 0xFB40 each time. If all the signatures match then the ROM is good.

The ROM is different across each version of this game so make sure you compare it with the right file.
This method will probably work on the bootlegs too with some minor changes to the procedure.

SOIC-n to DIP adapter

Arduino 2 Responses »

Oct 122014

I recently came across a nice looking IC that I wanted to try out.
The actual device in question is the AD8400ARZ1 from Analog Devices and is a digital potentiometer that in a narrow SOIC package.
As Im wanting to use this with some Arduino projects I wanted to be able to use it on prototype board which requires a DIP package.
I made a nice small board up in Eagle and am currently waiting on the boards coming from OSHPark. It ended up costing me something like 70p for 3 as they are tiny.

EDIT: Mike kindly pointed out in the comments that I should have checked eBay first. This is a very good point and ive got into the routine of not checking eBay for anything these days but when there are big savings in both time and money to be made then its definitely worth a go.
Thanks Mike for pointing this out. At least there was no great amounts of cash spent on it.

Jumping PCB info

General, Technical Info 1 Response »

Oct 052014

Been doing a few bits with muddymusic’s Jumping PCB.
I wanted to see how the C-Chip substitute ROM was wired into the circuit so ive made a small schematic and reversed the address decoder PAL.

click the pic for full size.

Here are the equations for the address decoder too. Ive renamed to the pins to something more suitable for human consumption.
/* Inputs */

Pin 1 = A23;
Pin 2 = A22;
Pin 3 = A21;
Pin 4 = A20;
Pin 5 = A19;
Pin 6 = A18;
Pin 7 = A17;
Pin 8 = A16;
Pin 9 = A15;
Pin 10 = A14;
Pin 11 = A13;
Pin 13 = FC0;
Pin 14 = FC1;
Pin 23 = FC2;

/* Outputs */

Pin 15 = CA12; /* A12 of C-Chip replacement ROM */
Pin 16 = CA13; /* A13 of C-Chip replacement ROM */
Pin 17 = CA14; /* A14 of C-Chip replacement ROM */
Pin 18 = CA15; /* A15 of C-Chip replacement ROM */
Pin 19 = LROM; /* Chip enable for other ROM’s */
Pin 20 = A; /* Pin 1 of 74LS138. Input A */
Pin 21 = B; /* Pin 2 of 74LS138. Input B */
Pin 22 = C; /* Pin 3 of 74LS138. Input C */

/* Equations */

!CA12 = !A23 & !A22 & !A21 & !A20 & !A19 & !A13 #
!A23 & !A22 & !A21 & A20 & !A19 & !A18 & !A17 & !A16 & A15 & A14 & !A13 #
!A23 & A22 & !A21 & !A20 & !A19 & !A18 & !A17 #
!A23 & A22 & !A21 & !A20 & !A19 & !A18 & A17 & A16 #
A23 & A22 & !A21 & !A20 & !A19 & !A18 & !A17 & !A16 & !A13 #
!A23 & !A22 & !A21 & !A20 & A19 & !A18 & !A17 & !A13 #
A23 & A22 & !A21 & A20 & !A19 & !A18 & !A17 & !A16 & !A15 & !A14 & !A13;

!CA13 = !A23 & !A22 & !A21 & !A20 & !A19 & !A14 #
!A23 & A22 & !A21 & !A20 & !A19 & !A18 & A17 #
A23 & A22 & !A21 & !A20 & !A19 & !A18 & !A17 & !A16 & !A14 #
!A23 & !A22 & !A21 & !A20 & A19 & !A18 & !A17 & !A14;

!CA14 = !A23 & !A22 & !A21 & !A20 & !A19 & !A15 #
A23 & A22 & !A21 & !A20 & !A19 & !A18 & !A17 & !A16 & !A15 #
!A23 & !A22 & !A21 & !A20 & A19 & !A18 & !A17 & !A15;

!CA15 = !A23 & !A22 & !A21 & !A20 & !A16;

!LROM = !A23 & !A22 & !A21 & !A20 & !A17;

!A = !A23 & !A22 & !A21 & !A20 & !A19 & !A18 #
!A23 & !A22 & !A21 & A20 & !A19 & !A18 & !A17 & !A16 & A15 & A14 #
!A23 & !A22 & A21 & !A20 & !A19 & !A18 & !A17 & !A16 & !A15 & !A14 & !A13 #
A23 & A22 & !A21 & !A20 & !A19 & !A18 & !A17 & !A16 #
A23 & A22 & !A21 & A20 & !A19 & !A18 & !A17 & !A16 & !A15 & !A14 & !A13;

!B = !A23 & !A22 & !A21 & !A20 & !A19 #
A23 & A22 & !A21 & !A20 & !A19 & !A18 & !A17 & !A16 #
!A23 & A22 & !A21 & !A20 & !A19 & A18 & !A17 & !A16 #
A23 & A22 & !A21 & A20 & !A19 & !A18 & !A17 & !A16 & !A15 & !A14 & !A13;

!C = !A23 & !A22 & !A21 & !A20 & !A19 #
!A23 & !A22 & !A21 & A20 & !A19 & !A18 & !A17 & !A16 & A15 & A14 #
!A23 & !A22 & !A21 & !A20 & A19 & !A18 & !A17;

The A, B and C outputs from the PAL feed into a 74LS138. In order to select the C-Chip substitute A and B must be HIGH and C must be LOW. From the equations (or just looking at the MAME source code) we can work out that the C-Chip ROM lies at address 0x80000.

So, not a great deal of info but its pretty interesting all the same.

Another Jumping PAL dump

PAL Updates Comments Off

Oct 052014

I dumped another PAL from the Jumping board today. Like the other this one was unlocked so now we have a full set of PAL dumps for the Rainbow Islands bootleg.
This PAL is found on the lower PCB of the stack.

U.S Navy and Jumping PAL dumps added

PAL Updates Comments Off

Oct 042014

muddymusic dumped the PAL from his U.S Navy CPS1 board and has tested it. It is marked as CA22B.
Ive also got a Jumping board from muddymusic’s which I am currently working on. There is a PAL20L8 chip that does the address decoding for the CPU which is now dumped. At this point Ive not tested it as the board set is in bits but I will test as soon as I can. The device is also unlocked so im pretty confident the dump will be OK.

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