Ei Os Descriptor (Isd) - Fujitsu MB90895 Series Hardware Manual

CHAPTER 3 CPU
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3.5.11 EI OS descriptor (ISD)
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The EI OS descriptor (ISD) is allocated to the addresses "000100
internal RAM, and consists of 8 bytes x 16 channels.
I Configuration of EI
ISD consists of 8 bytes x 16 channels, and each ISD is composed as shown in Figure 3.5-10. Table 3.5-9
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"EI OS Descriptor (ISD) Area" shows the correspondence between the channel number and ISD address.
ISD head address
(000100
H
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ICS: EI OS channel select bit (ICR: ICS3 to ICS0)
Table 3.5-9 EI
(ICR: ICS3 to ICS0)
80
2
OS Descriptor (ISD)
Figure 3.5-10 Configuration of EI
MSB
Data counter upper 8bit (DCTH)
Data counter lower 8bit (DCTL)
I/O address pointer upper 8bit (IOAH)
I/O address pointer lower 8bit (IOAL)
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EI OS status register (ISCS)
Buffer address pointer upper 8bit (BAPH)
Buffer address pointer middle 8bit (BAPM)
Buffer address pointer lower 8bit (BAPL)
+ 8 × ICS)
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OS Descriptor (ISD) Area (1/2)
Channel
0
1
2
3
4
5
6
7
2
OS Descriptor (ISD)
Descriptor header Address
000100
H
000108
H
000110
H
000118
H
000120
H
000128
H
000130
H
000138
H
" to "00017F " in the
H H
LSB
H
L