NSM Festival 160
My great Rock-Ola 451 only has room for 50 singles, so this 80 single, or 160 selection jukebox gives more freedom of choice.
The NSM is also more gentle to the records than the 10 years older, but of course more good lookin Rock-Ola
that will move to my gameroom for "sunday use only" while the NSM stays home.
NSM ES CPU board is from 1980, meaning the on board EPROM chips are already 28 years old.
That is almost the limit of EPROM data retention, so it would be a good idea to burn new EPROMs and have
the code safe for another 30 years. But, the three supply voltage 2708 chip is no longer supported by modern
EPROM programmers. So I had to make a special adapter to read the chip contents. And how about writing it?
No chance! The original board had one 2708 and one 2716 chip, so totally 3 kilobytes of program code.
A 4k 2732 chip will be enough, and those can be handled by most programmers. It needs a little wiring
Between the 2732 and CPU board IC6 socket, an extra socket is needed so a few wires can be re-routed:
2732 pins 18,19,20 and 21 do not touch the IC6 socket corresponding pins. All other do.
- 2732 pin 21 is connected to IC14 (74LS04) pin 3 (A11).
- 2732 pin 20 is connected to 2732 pin 18 (/CE).
- Pins 20+18 are connected via an 1N4148 diode to IC13 (74LS139) pin 5, diode cathode to IC13 side.
- Pins 20+18 are connected via an 1N4148 diode to IC14 (74LS04) pin 4, diode cathode to IC14 side.
- Pins 20+18 are then connected via a 4.7k pullup resistor to pin 24, +5V.
- 2732 pin 19 is connected to IC6 socket pin 20.
If you can't read the 2708, download here the 2732 image.
Festival is now playing at his new owner.