Sigma BM-286A service manual Theory of Operation

4. THEORY OF OPERATION page 29

4.2.2. Computers and Power Supply:

Refer to "BM-286A Wiring Diagram" Drawing 3 and"BM-286A Electronics Component Designator" Drawing 4. (Appendix F.).

There are two computers, one a DOS base unit with a TSA circuit card (CIF-553) and the second a Windows NT machine. Communication between them is handled by RS-232 via COM1 on both machines. The computers both have passive back planes with plug in computer cards.

DOS unit: 8 megabytes (MB) of RAM, a hard disk drive, and a 3 ½" floppy drive. The hard drive contains the DOS operating system and operating program. The program directory includes a support file with the discriminator settings.

WINDOWS NT: 32 megabytes (MB) of RAM, a hard disk drive, and a 100 MB Zip drive. The user, setup, and waste streams are stored on the hard disk. The machine receives data from the DOS machine on COM1, scale data on COM3, and touch screen data on COM2.

4.2.3. Backplane Card, RCS-130:

Refer to "RCS-130 Schematic Diagram" Drawing 10, "RCS-130 Component Designator Front" Drawing 11 and "RCS-130 Component Designator Rear" Drawing 12 (Appendix F.).

The backplane card is a passive board that contains these connectors:

•Eleven - 44 pin edge card connectors

•One - 50 pin ribbon cable connector

•One - 34 pin ribbon cable connector

•Ten - MHV chassis connectors

•One - 5 pin power connector

•One - 8 pin external connector for control

Model BM-286A