IBM 5150 PC Technical Reference (6025005, August, 1981) (PDF)

Notes For The BIOS Listing
1. The wait loop for the printer times out on form
feed of >51 lines. - line ref (3069)
2. Mode controls for the 320 x 200 video have
Color/BW reversed. - line ref (3338)
3. The RS232 Timeout is 80 decimal, not SO
hexadecimal. - line ref (1566)
4. The Base Pointer register is destroyed by some
video calls.
5. D_04 0 character in the character generator has
OS as it's last value, S/SO. -line ref (5511)
6. If you hit print screen in the Color/Graphics
80x25 Character Mode, the screen may not
display during the print cycle.
A-Sl