Fluke Biomedical 956A-201-M2 - Manual (Page 57)

3-31
Table 3-9. Data Entry Read Functions
Data Bit Function
D0 Enter Switch (Active Low)
D1 Value Select Switch (Active Low)
D2 Digit Select Switch (Active Low)
D3 (Not Used)
D4 (16 position function switch, see Table 3-16)
D5 (16 position function switch, see Table 3-16)
D6 (16 position function switch, see Table 3-16)
D7 (16 position function switch, see Table 3-16)
Table 3-10. Function Switch Logic
Hex Data D7 D6 D5 D4 Position Function
F 1 1 1 1 0 High
E 1 1 1 0 8 Calibrate Mode
D 1 1 0 1 1 Warn
C 1 1 0 0 9 Undefined
B 1 0 1 1 4 Overrange
A 1 0 1 0 C Undefined
9 1 0 0 1 5 Conversion Constant
8 1 0 0 0 D Undefined
7 0 1 1 1 2 Tau
6 0 1 1 0 A Undefined
5 0 1 0 1 3 Full Scale Value
4 0 1 0 0 B Undefined
3 0 0 1 1 6 Undefined
2 0 0 1 0 E Undefined
1 0 0 0 1 7 Low Scale Value
0 0 0 0 0 F Undefined
PROM
The Programmable Read Only Memory is typically a 27256 that is a UV erasable 32K x 8-bit PROM. U23,
which responds to address 8000-FFFF, is always present. U23 contains the operating program for the
digital ratemeter (UDR). Jumper JP2 is normally set between pins 2 - 3. By setting JP2 at 2 - 3, A14 is
applied to pin 27 of U23, allowing the use of a 27256 PROM (32K x 8). Position 1-2 is provided for a type
27128 PROM (16k x 8) no longer used.
RAM
Dynamic Random Access Memory (U21) is utilized for temporary data storage. U21, which responds to
address 0000-1FFF (8K x 8 bit), is always present. Data stored in the RAM is lost on power down. U22 is
provided for future RAM expansion, and will respond to address 2000-3FFF.
E 2
Sixteen monitor specific, operator entered setpoints are stored in 64 bytes of non-volatile electrically
erasable memory (E
2 ). U33 provides storage for the setpoints (256 bytes max.). U35 is an 8-Bit control
register to permit transferring set point information to and from the data bus.