DTS Model 412B System Memory Module

The Model 412B System Memory Module plugs directly into the slot provided for the Traffic PROM Module in any Model 170 Controller meeting the State of California TSCE Specification. The Module is fully buffered on sixteen address and eight data lines and is extremely versatile, providing various jumper selectable configurations of SRAM (Static Random Access Memory), EPROM (Electrically Programmable Read Only Memory), EEPROM (Electrically Erasable and Programmable Read Only Memory), and NOVRAM (Non-Volatile Random Access Memory). Capabilities of the Module include an on-board +12 vdc to +5 vdc dc/dc converter power supply and a Super Capacitor standby power source for RAM data retention or a rechargeable lithium battery that converts all SRAM to Nonvolatile RAM making EEPROM unnecessary.

The two most popular configurations are:
1. 1-EPROM (27256) @ hex address 8000-FFFF, 1-Nonvolatile SRAM(62256) @ hex addresses 800-4FFF and 7000-7FFF (Wapiti local configuration)

2. 1-EPROM (27256) @ hex address A000-FFFF, 1-Nonvolatile SRAM(62256) @ hex addresses 800-4FFF, 7000-7FFF, and 8000-9FFF (Wapiti master configuration)

Four twenty-eight pin sockets and two twenty-four pin sockets allow various combinations of JEDEC compatible devices: 2764, 27128, and 27256 EPROM; 6264 and 62256 SRAM or NOVRAM; 2816 EEPROM. Memory mapping for the various sockets is contained in programmable EPROM IC5. One of eight configurations may be selected by installing the proper combination of configuration jumpers J71-J73. Configurations other than the eight standard are available on special request. Jumpers J11-J76 allow for the selection of size and type of memory chip and standby power. During a power failure the contents of SRAM are protected from corruption by a WRITE PROTECT circuit that monitors the DC voltage of the Module. Optionally, a rechargeable lithium battery and nonvolatile controller chip convert all SRAM to Nonvolatile RAM with power fail protection.

Power to the Module is supplied from a DC/DC converter that supplies +5 vdc from +12 vdc with a conversion efficiency of 81%. As a result very little heat is generated by the unit.

If neither the Nonvolatile RAM nor the on board battery option is selected, then a 0.1 farad Super Capacitor may be used and is kept charged to +5 vdc during normal operation. At power failure this capacitor provides power to each RAM chip so jumpered and also to the Write Protect circuit. Under test the full RAM compliment was powered in excess of thirty hours without data corruption. The optional rechargeable lithium battery with nonvolatile controller chip protects the integrity of all module RAM contents against any power fail condition. A battery charge circuit is included on the module.

Memory EPROM	2764,27128,27256 @ 200 nsec.; SRAM: 6264,62256 @ 200 nsec., 2 microamp @ 2vdc battery mode; NOVRAM: Dallas 1225Y,1230Y @ 200 nsec. or rechargeable lithium battery w/nonvolatile controller chip w/62256 RAM; EEPROM: 2816 @ 350 nsec.
DC/DC Converter Type	Motorola MC34063P1; Current: 1.5 amp max. w/current limit; Input: 2.5 to 40 vdc; Efficiency: 81% at an output of 5 vdc, 1 amp.
Standby Source	0.1 farad, 5.5 vdc Super Capacitor. Approximately 830 microamp-hr capacity. Rechargeable lithium battery with charge circuit. Single charge provides over five years operation.
Circuit Board	5" x 10.375" x 0.063" thick, NEMA F-4 glass cloth, soldermask both sides, component silkscreen, gold plated edge connector contacts, and humidity resistant conformal coating.
Front Panel	1.5" x 5.0" x 0.125" thick, clear anodized aluminum, handle, and anti-insertion device.
Miscellaneous	Weight: 10 oz.; Operating Temperature: -37 to +74 degrees C; Power Requirements: 95 ma max. @ +5 vdc, 160 ma max. @ +12 vdc