4.5 Data System

 

4.5.6 Output Ports

 

For all strobe and anti-strobe bits, a zero indicates the lower threshold is in use; a one, the higher threshold. For all power bits, a zero indicates power is off, a one indicates power is on. The command pending telltale indicates that one or more commands have been loaded and should be executed at the end of the current cycle. The bias select bit being one indicates that the higher detector biases (125V, 2-1/2V) are in use, a zero indicates the lower biases (100V, 2V).

 

All of these bits are invalid if the power down telltale bit is a one.

 

4.5.7 Analog Housekeeping MUX

 

Twelve analog housekeeping channels will be multiplexed to three channels. The three groups of four channels will be switched synchronously at the occurrence of the format pulse. All outputs will be O V< V < 5.1 V.

 

AHK MUX

 

Address	AHK1	AHK2	AHK3	AHK4
00	Int. Cal.	+10 V-Ref	CD-Temp	Current
01	Int. Cal.	+10 V	F-Temp	Current
10	Int. Cal.	+6 V	D-Temp	Current
11	Int. Cal.	V-Bias	23-Temp	Current

 

These channels are switched at the beginning of each format.

 

Singles MUX. Eight singles rate channels will be multiplexed to two channels. The two groups of four channels will be switched synchronously at the end of each spin group pair. Note that these bits serve to indicate whether the addresses are switching and do not relate a channel to a given format of data.

 

Spin Group Pair	Singles MUX Address	S1 Type	S2 Type
1	00	B1	M
2	01	C0	F
3	10	Not Used	M'
4	11	D1	F'
5	00	B1	M

 

4.5.8 Spectrum Accumulator Data

 

The MFSA assigns events to 1 of 32 bins, and passes 32, 8-bit counts to the data system. The data system enables or inhibits the MFSA according to the MFSA schedule table, and sums the 8-bit count with one of four, 32 byte x 16-bit counts in RAM. At the end of each cycle, the resulting 128, 16 bit counts are log compressed to 128, 8-bit bytes of the form:

 

 

The value of this count is

 

(16 + E x 8 + F x 4 + G x 2 + H) x 2 (A x 8 + B x 4 + C x 2 + D -1 )

 

However, when the component is zero, then the value equals the mantissa. The largest count without an overflow is then 220 -1 , but this count is limited to 216 -1 by the size of the summation register.

 

4.5.9 Output Sequence

 

MFSA data will be output in the following sequence:

 

 

 

Next: Chapter 4.5.10: Rate and Composition Aperture Data