Service manual

SERVICE MANUAL
25
1-9. IC11 FAS236U (SCSI Controller)
1-9-2. Pin Descriptions
Pin No. Signal name Dir Explanation
100 DREQ out DMA request. H: ready to transfer data.
1 /DACK in DMA acknowledge.
2 /DBWR in Data-bus write control.
4 IGS out Indicates that chip is acting in initiator mode.
5 DIFFSENS in H: differential mode.
6 TGS out Indicates that chip is acting in target mode.
7 EDIFFS in H: Enable “DIFFSENS” function.
8-15
19-26
DB[15:0] i/o DMA data-bus.
16,27 DBP[1:0] i/o DMA data-bus parity.
29-36 /SDI[7:0] in SCSI data bus.
37 /SDIP in SCSI data parity.
42-45
48-51
/SDO[7:0] out SCSI data bus.
52 /SDOP out SCSI data parity.
56 /SELO out SCSI bus select.
57 /BSYO out SCSI bus busy.
58 /REQO out SCSI bus request.
59 /ACKO out SCSI bus acknowledge.
62 /MSG i/o SCSI bus message phase.
63 /CD i/o SCSI bus control and data phase.
64 /IO i/o SCSI bus I/O phase.
65 /ATN i/o SCSI bus attention.
66 /RSTO out SCSI bus reset.
69 /SELI in SCSI bus select.
70 /BSYI in SCSI bus busy.
71 /REQI in SCSI bus request.
72 /ACKI in SCSI bus acknowledge.
73 /RSTI in SCSI bus reset.
74,75 MODE[1:0] in Bus configuration mode select.
76 /INT out Interrupt output.
77 RESET in Power reset.
79 /WR in Write control.
80 /RD in Read control.
81 /CS in Chip select.
82-85 A[3:0] in Address bus.
86 CLK in Internal chip timing clock.
87 /DIFFM in H: single-endes mode. L: differential mode.
90-93
96-99
PAD[7:0] i/o PAD bus. Connected with CPU for communication.
38,88 VDD - +5V DC power input.
17,18,40
41,46,47
54,55,60
Vss - GROUND. 0V DC power return.
61,67,68
94,95