Texas Instruments Extensa 660 Series Maintenance Manual page 84

Figure 5-8 CD-ROM Interface Troubleshooting Diagram
5-24 Troubleshooting Procedures
System Fails to Boot:
7
CD-ROM Interface Checks
Checked CD-ROM Power?
Yes
Checked CD-ROM Data
Bus?
Yes
Checked CD-ROM
Address Bus?
Yes
Checked IRQ Signal?
Yes
END
Check U605(9956) Pin1
No
VCC-CDROM=5V
Check U13
PIN 36, 37, 38, 39, 50,
No
51, 52, 53, 62, 63, 64,
65, 71, 72, 73, & 74
Check U13
PIN68, PIN69, PIN70,
No
HSA0, HSA1, HSA2
Check U13 Pin86,
No
DIRQ15