Update firepower to 7 digit displays
Testing the roms...:
(one digit is missing, maybe a 6184...)
Firepower is a great (or maybe the greatest) system 6 Williams game.
The system 6 game roms all share the same green flipper rom.
In this rom there are a lot common routines for all games coded:
driving:
the lamps, solenoids, sound, the 6 digit display board
handling: the player score, the match routine,
checking: common switches (like creditbutton, coins) and a lot more.
Two system 6 games (Alien Poker and Algar) uses the 7 digit display board from system 7.
How does the 6 display update work:
The strobe lines are responsible for matching the correct digit position on the displays.
First, the display update routine starts at strobe line 1.
Every player score is decoded to bcd (binary code decimal: a 1 is coded as 0001, a 2 is coded as 0010).
Then two player score information is put together:
Exampel player 1 and player 3:
score player 1 score player 3
010'000 000'020
bcd player 1 bcd player 3 Digit combined bcd
0000 0000 1 00000000
0000 0010 2 00000010
0000 0000 3 00000000
0000 0000 4 00000000
0001 0000 5 00010000
0000 0000 6 00000000
The MPU takes the relevant bcd information for strobe line 1 and sends these combinded bcd-informations through the pia 1 (the 6821 chip on the mpu board).
Then the combinded bcd-informations for the next strobe line is built and send.
This process repeats for the 16 strobes lines. Then the process start over and over.
Firepower strobe / 6 digit table
Strobe Line 6 digit J5/pin digit
1 6 #1 100'000 #3 100'000
2 7 #1 10'000 #3 10'000
3 8 #1 1'000 #3 1'000
4 9 #1 100 #3 100
5 10 #1 10 #3 10
6 11 #1 0 #3 0
7 3 credit right middle (3)
8 2 credit right (4)
9 15 #2 100'000 #4 100'000
10 12 #2 10'000 #4 10'000
11 13 #2 1'000 #4 1'000
12 17 #2 100 #4 100
13 16 #2 10 #4 10
14 14 #2 0 #2 0
15 5 credit left (1)
16 4 credit left middle (2)
nc 1
nc 18
From the mpu view the difference between the 7 digit display board and the 6 digit display board is minimal:
The 7 digit board supports commas and uses two additional strobe lines.
The display strobe lines are arranged in an other way than on the 6 digit display boards.
The bcd lines are the same.
So, how can alien poker and algar use the 7 digit display board with the green flipper roms ?
Well, Willimas coded for these two games a little bit around the green flipper roms. The player score is still stored with 6 digits internally, but every player score is dived by 10 and during the update from the display board (which is programed in the game rom), one fake 0 is added at the rightmost position.The match routine from the green flipper rom is also altered.
When a 7 digit display board is connected to a firepower with the existing mpu firepower cabel to display connector J5, the strobe table should look like this:
Firepower strobe / 7 digit table
strobe Line 7 digit J5/pin digit
1 6 #1 1'000'000 #3 1'000'000
2 7 #1 100'000 #3 100'000
3 8 #1 10'000 #3 10'000
4 9 #1 1'000 #3 1'000
5 10 #1 100 #3 100
6 11 #1 10 #3 10
7 3 #1 0 #3 0
8 2 #2 1'000'000 #4 1'000'000
9 15 #2 100'000 #4 100'000
10 12 #2 10'000 #4 10'000
11 13 #2 1'000 #4 1'000
12 17 #2 100 #4 100
13 16 #2 10 #4 10
14 14 #2 0 #2 0
15 5 credit left (1) credit right middle (3)
16 4 credit left middle (2) credit right (4)
nc 1
nc 18
Well, I did these modifications to the firepower roms.
The modifcation should run with a system 6 board. I had one system 7 board lying around, so I did a complete MPU board swap.
How to convert a firepower to 7 digit displays:
First remove the 6 digit master and the four slave boards.
Install jumpers J2 and J4 on the master display board. (display works without commas).
Now install the four 7 digit player displays. The upper left and right screws from the 7 digit slave display boards matches perfectly the existing screwholes. For the other two screws new holes must be drilled.
The credit display is a little bit more complicated:
Mark the excat location from the display glas on the wood
Remove the credit display.
Connect these lines on the wood
All displays are mounted.
(and my cat is watching me....)
For the cable holes I used a "forstner"-driller.
Important: Remove the displays before drilling the cable holes (I almost ruined a display connector...)
Mount the 7 display master board on the backside.
Make sure that the screws from the display master board don't touch a wire !.
The System7 CPU board should be set for any game other than Hyperball/Defender.
After power on, you should see the version number in the player two display.
Modification is done at your own risk...
Here are some pictures of another "upgraded" machine (someotherguy)
Mail me