I would bet good odds that it's 1- 5V and
2- has a parallel bus interface that would be easily adapted to work with any modern microcontroller that can address external memory.I did find this link:
http://d.hatena.ne.jp/redeel/20090508/1241808117 which show a mask ROM microcontroller
I also found
someone's memoirs that contain the following text:
Quote:
Atari's Pong [...] triggered the development of NEC single-chip television game processor LSI, µPD777, in which I was involved starting 4/1977 until 4/1978. Because the frequency of VHF (Very High Frequency) television channel 3 & 4 was different between US and Japan, I had to calibrate the frequency to get the right game screen on television set opening the lid in Japan.
[... in another document a formal certificate with the subtitle:]
For the development of single-chip video game processor LSI, µPD777, µPD778, from NEC (3/14/1984)
... Wait, he's already got this mostly together:
he still has the documentation from the time on how he designed it<eats my words>
The µPD777 is a
single-chip video game processor. It natively emits component, s-video, and composite video, and per Mr. Oguchi's documentation, we are told the pinout of the 42-pin DIP it came in:
Code:
1|/K1 Φ|42
2|/K2 VDD|41
3|/K3 nc|40
4|/K4 nc|39
5|/K5 nc|38
6|/K6 PD1|37
7|nc PD2|36
8|nc PD3|35
9|nc PD4|34
10|/K7 /GP|33
11|R-Y /GP&SW|32
12|REF CH1|31
13|B-Y CH2|30
14|CROMA CH3|29
15|VIDEO CH6|28
16|R(1-3) CH4|27
17|G(1-2) /S4|26
18|REV /S3|25
19|SOUND /S2|24
20|/AC /S1|23
21|GND nc|22
I think there's enough information on his web site to create an FPGA softcore, but I'm not confident. There's certainly no other way to program for it: it does not seem to have ever been released in a version that could address external or internal programmable memory.
This person has a picture of the inside of the base console.
and
this person has (mostly) traced the 36-pin cart connector (to build a replacement base station)
and
this person has taken things apart, but the pictures are less useful.
plgDavid's looked into this before.
As has SlyDC.