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Help diagnosing a IBM 5140 Convertible

nestor

Veteran Member
Joined
Jul 23, 2010
Messages
509
Location
Spain
I have a IBM Convertible 5140 that behaves this way:


After power switch is pressed, it produces a continuous beep and nothing more. Watching other 5140 videos on youtube, it seems that this beep should be very short. Disassembling the BIOS I saw that between the beep on and the beep off instructions there are some test operations.

I modified the BIOS to produce a changing beep, and it is produced without problems:


What do you think I should do next?
 

modem7

Veteran Member
Joined
May 29, 2006
Messages
7,789
Location
Melbourne, Australia
Disassembling the BIOS I saw that between the beep on and the beep off instructions there are some test operations.
What do you think I should do next?
One of those "test operations" may be to validate the checksum of the two BIOS ROMs. Does the content of your two ROMs match the two 5140 ROM images at http://members.dodo.com.au/~slappanel555/rom/rom.htm ?

Note: There was only one BIOS revision for the 5140, one dated 13SEP85, and so the comparison is valid.
 
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