Toshiba libretto U100 Maintenance Manual page 65

2.4 System Board Troubleshooting
5. Execute GETDPORT.COM in the text menu in CPU REAL mode. (Insert the FD for
starting D port into FDD and input "FD starting drive:>dport".)
The D port status is displayed in the following form;
6. When the D port status is FFFFh (normal status), go to Procedure 3.
7. When the D port status falls into any status in Table 2-4, execute Check 1.
libretto U100 Maintenance Manual (960-520)
2 Troubleshooting Procedures
[CONFIDENTIAL] 2-21