THE STEERING POST DISPLAY SYSTEM
http://www.capcomespace.net/dossiers/espace_US/shuttle/sts/orbiter_avionique.htm
Originally, the Orbiters were equipped with the Multifunctional CRT Displays System or MCDS. In 1998, this system was replaced by the Multifunctional Electronics Display System MEDS. The MCDS is made up of three types of materials:
_ 4 electronic screens DEU (Display Electronics Unit),
_ 4 DU (Display Units) screens which include CRT screens
_ 3 control keypads communicating with the GPCs via bus network.
Three DU displays and two keyboards are mounted on the main panel, and one with a keyboard on the side workstation. Each of the 4 DEUs communicates with the data from the GPC on-board computers.
The DU screens are CRT electronic screens displaying alphanumeric characters, graphic symbols and arrows in fluorescent green. They are not able to represent a complex shape, being limited by lines or arrows. Each screen has a contrast and brightness setting. If one of the CRTs breaks down on the main panel, the crew can exchange it with that of the rear station to ensure the return of the mission.
When the MCDS is installed, indicators ensuring the need for the primary flight instrument necessary for manual flight or automatic control of the piloting system are arranged in front of the pilots and aft on the "hold" workstation. These indicators include the ADI (for flight direction), two HSI (horizon indicator), AMI (Mach indicator), AVVI (vertical speed indicator and altimeter), position of flight indicators, RCS system light and G meter.
The HUD head-up viewfinder is an optical system which makes it possible to visualize the reentry data during the reentry phase, the final approach to the runway. It uses the same data as the edge indicators and displays them on CRT screens to create an image which is projected through a series of lenses to combine on a window located in front of the portholes in direct view of the pilots. The system was not originally installed on the OV 101 and 102, but on the others from their construction. Columbia was fitted after STS 9.
Regarding the installation dates of the Multifunction Electronic Display System (MEDS):
http://www.capcomespace.net/dossiers/espace_US/shuttle/sts/orbiter_avionique.htm
In 1988 Rockwell embarked on a program to modernize the Orbiters' cockpit. At that time, it naturally came to mind to use the "glass cockpit" like commercial aircraft. This system allows data to be displayed on color screens to replace conventional indicators. In 1992, this program was perfected for its use, thus born the Multifunction Electronic Display System MEDS.
MEDS uses 11 multi-function MDU color screens, 4 so-called IDP (Integrated Display Processors) screens and 4 ADC analog-digital converters per vehicle. 9 screens are installed in front of the pilots to replace the three CRT screens and indicators. The other two are installed in the aft cockpit. The MDU screens are based on those fitted to B777 aircraft modified to use an LCD produced in the USA. They are slightly larger than the old ones but provide better lateral vision, have better definition with 48 colors (16 tones of each primary).
The MEDS program was originally spread over two phases, one at the KSC with the replacement of the three classic screens with three MDUs, then during the OMPDs, the indicators would be replaced by three MDUs. The installation of the MEDS slightly increases the mass of the Orbiters by 250 kg, the consumption and the heat dissipation being equivalent (1600 W).
Atlantis is the first Orbiter to receive MEDS in 1998 during its OMPD. He flew for the first time in May 2000 on STS 98.
Columbia received his MEDS in 2000.
Discovery received it in 2002-2003 during his OMPD 3.
And Endeavour received it in 2004-2005. Note that these last two OMPD take place at the KSC.