Hello, I am just using Philips ISP1181a USB high speed Interface device for commuicating USB host. Philips provided the standard C programs for interface the 8051 microcontroller with isp1181a,it shows some errors while i am compiling and it shows the some Linking error ERROR L118: REFERENCE MADE TO ERRONEOUS EXTERNAL SYMBOL: IOREQUEST MODULE: .\D13bus.obj (D13BUS) ADDRESS: 0947H *** ERROR L118: REFERENCE MADE TO ERRONEOUS EXTERNAL SYMBOL: IOREQUEST MODULE: .\D13bus.obj (D13BUS) ADDRESS: 094CH *** ERROR L118: REFERENCE MADE TO ERRONEOUS EXTERNAL SYMBOL: IOREQUEST MODULE: .\D13bus.obj (D13BUS) ADDRESS: 095EH *** ERROR L118: REFERENCE MADE TO ERRONEOUS EXTERNAL SYMBOL: IOREQUEST MODULE: .\D13bus.obj (D13BUS) ADDRESS: 096FH *** ERROR L118: REFERENCE MADE TO ERRONEOUS EXTERNAL SYMBOL: IOREQUEST MODULE: .\D13bus.obj (D13BUS) ADDRESS: 0980H *** ERROR L105: PUBLIC REFERS TO IGNORED SEGMENT SYMBOL: GENEPBUF SEGMENT: ?ID?ISR *** ERROR L105: PUBLIC REFERS TO IGNORED SEGMENT SYMBOL: IOREQUEST SEGMENT: ?ID?ISR *** ERROR L105: PUBLIC REFERS TO IGNORED SEGMENT SYMBOL: INTRAMBUF SEGMENT: ?ID?ISR *** ERROR L118: REFERENCE MADE TO ERRONEOUS EXTERNAL SYMBOL: IOREQUEST MODULE: .\Mainloop.obj (MAINLOOP) ADDRESS: 1298H *** ERROR L118: REFERENCE MADE TO ERRONEOUS EXTERNAL SYMBOL: IOREQUEST MODULE: .\Mainloop.obj (MAINLOOP) ADDRESS: 0F19H it shows these errors ,anyone could help me for same. Regards Gobinath.K