Texas Instruments 990 Operation Manual page 259

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APPENDIX G
ADDITIONAL USER TABLES
Additional information related to PROM programming is presented in tables G-I through G-5.
Number
2
3
4
5
6
Table G-l. Pulse Widths
Multiplier Pulse Width (ms)
2 0.5
4 1.0
8 2.0
16 4.0
32 8.0
64 16.0
The number (x) is used as an exponent to get the multiplier, which is 2x. Hardware uses the
multiplier to produce the corresponding pulse width.
Table G-2. Minimum, Standard and Maximum Pulse Widths
and Duty Cycles
Pulse Width (ms)
Duty Cycle
TTL
PROM Types
188A, 8188, 8288,
8287, 8387, 8470,
8471, 8472, 8473
EPROMs
2704,2708
Minimum
I
0.1
Note:
TTL PROM types have the prefix 8N74.
Standard
I
Maximum
Minimum
I
Standard
I
Maximum
2
20 25% 35%
0.1
50% 50%
G-1
Digital Systems Division