Ports missing in Ubuntu8.04 ttyS4 and ttyS5

Hi,

I have two computers which are used by two manchines. one of the computer has Ubuntu 14.04 and in it all Serial ports are working fine, when comes to another computer it is using 8.04 but 2 serial ports are missing in it ttyS4 and ttyS5.

Ubuntu 16.04 it shows like this

$ dmesg |grep ttyS
[ 1.813244] 00:03: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[ 1.843455] 00:04: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 115200) is a 16550A
[ 1.875041] 00:05: ttyS2 at I/O 0x3e8 (irq = 10, base_baud = 115200) is a 16550A
[ 1.907086] 00:06: ttyS3 at I/O 0x2e8 (irq = 10, base_baud = 115200) is a 16550A
[ 1.939658] 00:07: ttyS4 at I/O 0x2d0 (irq = 11, base_baud = 115200) is a 16550A
[ 1.972545] 00:08: ttyS5 at I/O 0x2d8 (irq = 11, base_baud = 115200) is a 16550A

In bios the seletings for 16.04 are correct
Serial port 1[3F8/IRQ4]
Serial port 2[2F8/IRQ3]
Serial port 3[3E8/IRQ10]
Serial port 4[2E8/IRQ10]
Serial port 5[2D0/IRQ11]
Serial port 6[2D8/IRQ11]

Ubuntu 8.04 it shows
$ dmesg |grep ttyS
[ 17.586999] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[ 17.587192] serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
[ 17.587976] 00:06: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[ 17.588380] 00:07: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
[ 17.588962] 00:08: ttyS2 at I/O 0xc80 (irq = 10) is a 16550A
[ 17.589376] 00:09: ttyS3 at I/O 0xc88 (irq = 5) is a 16550A

In bios the seletings for 8.04 are correct
Serial port 1[3F8/IRQ4]
Serial port 2[2F8/IRQ3]
Serial port 3[C80/IRQ10]
Serial port 4[C88/IRQ5]
Serial port 5[C90/IRQ10]
Serial port 6[C98/IRQ11]

So, can you please help me in fixing this Serial port issue.

Thank you,
Arun Getty.