This prototype board has also some modifications:

• The 150 ohms resistors R118, R119, R120 and R121 have been replaced by 0 ohm straps.
• The RAM is not a 8 KB like on others WPC-95, but a 32 KB, like on earlier WPC-S with DCS sound.
  The W3 and W7 straps are installed, providing full access to the RAM pages, using BANK1/BANK2 signals from ASIC.
• There is a special pin for plugin. Located near the pin 32 of the G11 EPROM socket, and connected to the ROMW signal from ASIC. The W5 strap is installed while W4 not, thus the EPROM is powered by VBATT instead of VCC.

Replacement of the R118..R121 looks logical, as there is no reason to install resistors on the E and Q lines, between ASIC/CPU/74LS14.

RAM capacity is maximized, may be for testing, but not used on production games.

Using ROMW signal and alternate power source for EPROM: we suspect that the prototype was using a NVRAM or something similar, instead of EPROM/EEPROM. May be a faster way to program, and test modifications of the code.

The "Generic Apple" SECURITY PIC has really a model type "123" as printed on the label.
"Apple" stand for Advanced Pinball Programming Logic Executive, the Williams's operating system for pinballs.
Using a logical analyzer, we confirm that the full serial number returned from the PIC is:

123 100037 72939

The internal key used to encode this number, is like as others official PIC : 000 (and not 123 nor 999 !).

So, it is mandatory that an associated EPROM exist with the same identifier.
We are looking for this 123 / Generic Apple EPROM.

Note also that, this PIC is not the one used on the benchtest fixture (60048 or 684-S), which have model 648 encoded.

modif2 (resized).jpg

modif1 (resized).jpg

Does this help?

IMG_3778 (resized).jpg

The blue board is from my NGG proto, red one I bought many years ago and not sure which machine it came from.

IMG_3782 (resized).JPG

Who Dunnit was the first game that had the prototype WPC 95 boards in it.

Check out this link, should be helpful. http://www.duke-of-pinball.com/pins4sale_wd_prototype.html

Hi,
Many thanks for the pictures of your boards and the link for Who Dunnit prototype.

Your red board look to be, the very first prototype of WPC-95.
While used on a NGG sample, the blue board has the caracteristics of later serial production, not a prototype.

Indeed: on your red prototype board, the date of manufacture is inked : 36-95, meaning week 36 of 1995. That was the first week of september.
Our green prototype has been manufactured two weeks later : 38-95, and there is also a stamp on, showing SEP. 28, 1995. that is coherent.
The only difference is the funny "green" SIP Resistor network installed on your.
Strangely, they use a 9R instead of the 10R. But may be, this was caused by an error in the WPC-95 schematic...
On previous WPC-S, pin 1 and 10 goes to VCC. On WPC-95, the schematic say pin 1 to GND... and this is wrong (and illogical). Indeed, the wiring is the same as WPC-S, both pin 1 and 10 goes to VCC !!!

Note that, on your RED board, the watchdog is permanently deactivated, using a 0 ohm strap at J203. On our board, a switch was installed.
Your board has also been modified later: it had received the service bulletin 86 modification (the diode and the resistor added to avoid battery discharge). This modification was not in place on our green board.

The prototype boards may be easily identified, as they have some visual difference from the production(on picture, bellow) :
- Only one big chemical caps C31 is installed (the second, C77 is missing).
- Some caps (C74, C75, C76) had been added to filter the power lines arround the ASIC.
- An unmarked (may be R129) resistor had been installed (service bulletin 86 ?)
- Another R130 resistor had been added.

2017-09-07_12h57_38 (resized).png

Seem you are interested in the differences between the boards, here is another one.
The use of 7408 (board A-20119) and / 7402 ( board A-21377) @ U27

https://pinside.com/pinball/forum/topic/wpc95-rev-9-u27#post-3548560

And about the WHO DUNNIT prototype:

Yes, the WD was the first pinball to receive a WPC-95 boardset.
But this one, sell from Duke-Of-Pinball is probably the original cabinet BUT NOT THE ORIGINAL CPU BOARD

Take a close look at the pictures of the CPU:
- YES, no doubt, this is a prototype board, but notice that the additionnal pin (near pin 32 of EPROM) is not installed.
- It use a standard SECURITY PIC with 544 100022 serial, and a production EPROM. Nothing abnormal here, as the WD was already in production, and there was no reason to change that.

It is clear that this board has been manufactured later and can't be the original that was used for testing.
Why ?
Have you noticed the two stickers on the board...

There is a paper label on the RAM ("warranty void if removed" with the number 52148100597 printed.
There is another label on the board : A-20119-50048
Thus... this board was coming from a model 548 : A SCARED STIFF !
May be a prototype of SS, but not a WD.

There is another evidence that this board has been manufactured later after august/sept 1995: the batch number printed on integrated chips.
Sure that the ASIC has a "9535" mark on it, meaning manufactured at end of august... but as this is a removeable component, it be replaced and not a valid reference for the manufactured date.
But, if you look at the welded components, like 74LS14 or 74LS244, the mark is "9546" indicating... NOVEMBER 1995 !!!
This is a non contestable evidence that this board has been manufactured after that the WD prototype was tested. And CANNOT BE the original board

Some great insight here noflip95. The blue board is out of my NGG prototype serial number 53661100010, not a prototype board, but definitely a prototype machine.The red one is, and was missing the u10 chip and game rom when I purchased it. It had fault from manufacture where a solder bridge between two resistors was causing a short. My technician fixed it and is now running in the NGG with a new pic chip and game rom.On boot up the numbers have changed. The WD is also a prototype and the power driver is numbers matching, but the AV and CPU appear to be later boards, but my point was that some WPC95 boards were rolled out before Congo and maybe someone like John Wart could chime in here and assist as he has a very high level of board and prototype knowledge.

I used to have a bunch of those Generic Apple pic chips that were in production boards from back when I worked for WMS. They were used for the dev systems for the programmers working on the game.