THE 8050/8250 DEVICE NUMBER

The 8050/8250 disk drives have been assigned device # 8 on the IEEE-488. However, it is possible for the digital board to be altered to select device numbers 8 thru 15.

At power-on reset, the three pins 22, 23 and 24 of the 6532 at location UP are read as a binary input. The factory supplied board has the pins tied to ground, so the inputs will read as binary 0's. By lifting one or a combination of pins, this input can be altered. The corresponding input will read as a binary 1 and is added to the base device number of 8 to derive the final device number. All subsequent communications will use this computed device number.

To compute the desired device number consider that pin 24 is the least significant bit and pin 22 is the most significant bit. For example, to select device # 9, pin 24 would be cut and the input would be read as 8 + 1 = 9. Lifting the remaining pins or combinations of pins will result in the additional device number selections.

DEVICE CHANGE PIN LOCATION