Bally Astrocade cartridge technical information.
Written by Ward Shrake. Last updated: May 15, 2001
Pinout of the Bally Astrocade cartridge port |
G G E G
r r n P r
o o a o o
u u A A b A w u
n A A A A A A A A D D D n D D D D D 1 1 l 1 A A e n
d 7 6 5 4 3 2 1 0 0 1 2 d 3 4 5 6 7 1 0 e 2 9 8 r d
=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=
1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
|
| This is a diagram of the cartridge port, seen as you face the slot and/or
insert a cartridge into it. Pins are numbered from left to right, starting at "1" and ending at "26". Pins 1, 13 and 26 are all tied to a common ground. The other pins (2 through 25) on the port correspond exactly to pins 1 through 24 on the type of ROM chip used most often by Bally, inside their cartridges: the "2364" ROM. This is not commonly in use now, but was widely used in its day, by both Bally and other companies. (The early Commodore computers such as the VIC-20 and C64 used them, for example.) My thanks to Jay Tilton, who first mapped this port out and posted a pinout diagram to Usenet on Mar 28, 1998. |
Pinouts of various ROM and EPROM chips |
Pinout diagram: "2364" ROM chip (24-pin ROM chip, 8K x 8 bit.)
____ ____
| !__! |
CA7 | 1 24 | +5 Volts
CA6 | 2 23 | CA8
CA5 | 3 22 | CA9
CA4 | 4 21 | CA12
CA3 | 5 20 | CS (Chip select, active low)
CA2 | 6 19 | CA10
CA1 | 7 18 | CA11
CA0 | 8 17 | CD7
CD0 | 9 16 | CD6 CA0 - CA12 are address lines.
CD1 | 10 15 | CD5 CD0 - CD7 are the data lines.
CD2 | 11 14 | CD4
GND | 12 13 | CD3
|__________|
Pinout diagram: "2732A" EPROM chip
(Standard 24-pin EPROM chip, 4K x 8 bit.)
____ ____
| !__! |
CA7 | 1 24 | +5 Volts
CA6 | 2 23 | CA8
CA5 | 3 22 | CA9
CA4 | 4 21 | CA11
CA3 | 5 20 | OE / Vpp (OE is active low)
CA2 | 6 19 | CA10
CA1 | 7 18 | CE (Chip select, active low)
CA0 | 8 17 | CD7
CD0 | 9 16 | CD6 CA0 - CA11 are address lines.
CD1 | 10 15 | CD5 CD0 - CD7 are the date lines.
CD2 | 11 14 | CD4
GND | 12 13 | CD3
|__________|
Pinout diagram: 2764A EPROM
(This is a standard, 8K x 8 bit memory chip)
____ ____
| !__! |
Vpp | 1 28 | Vcc (+5 Volts)
A12 | 2 27 | PGM (Active low)
A7 | 3 26 | N.C. (No connection)
A6 | 4 25 | A8
A5 | 5 24 | A9
A4 | 6 23 | A11
A3 | 7 22 | OE (Output Enable; Active low)
A2 | 8 21 | A10
A1 | 9 20 | CE (Chip Enable; Active low)
A0 | 10 19 | D7
D0 | 11 18 | D6
D1 | 12 17 | D5
D2 | 13 16 | D4
GND | 14 15 | D3
|__________|
|
| Notes on the pinout diagrams above: The only known EPROM that is
an exact pin-for-pin 2364 replacement is the costly and hard-to-find Motorola "MCM 68764". (Try https://findchips.com/.) The commonly used 2764 chips have 28 pins instead of 24. This means that they cannot be inserted directly into an original Bally-made game cartridge circuit board: four pins will have nowhere to go. A 2764 can be made to work, but to do so you must cut certain wiring traces on the circuit board and bend certain pins upwards, to manually re-route the different pins via short jumper wires. If you compare the pinout diagrams of a 2364 and a 2764 (above) you'll see that many pins correspond to the same locations, although not to the same numbering. Start comparing from the bottom, upwards. |