Videeo chip 8514/A

The first intelligent graphics  adapter was the IBM PGA  - professional  graphics adapter. This was based on  an 8-bit 8088  general purpose processer and provided  a resolution  of:

Ø   640 x 480 in 256 colourss form a palette of 4096

The PGA monitor controller was unpopular due to its higher  cost for the  performance offered . However , it did introduce a standard  software interface , PGL – Professional  Graphics Language that it still supported  by more modern graphics boards and it did  establish  IMA’s approach to high level graphics.   

IBM introduced the 8514/ A in 1987 as a closed hardware  product for us in its  own machines. (The 8514 is in fact  as IBM monitor  that comes bundled with the  AFDA – Advanced Functions Display Adapter – graphic card but  the two have  come to be known  as the 8514/A.) IBM never  published  details  of the product , which would  have established  and manufacturers  - notably  western digital  - have product  8514/A hardware. As no standard  was published  the only way  compatibility with real  IBM product  cab be assured is by making the hardware  an exact  copy – this is known  as register level compatibility.

 The 8514/A chip accepts graphics  commands  form the  main processor via specific  registers , much  in the same way  as the VGA hardware does. The difference  is that each command is  more sophisticated and achieves more. The 8414/A isn’t as  sophisticated   as a typical TIGA board and  it achieves its standardization by not allowing  any hardware  variations.  This once again  is more in the  spirit of earlier  graphics  standards , i.e.  a board either  was or was  not  VGA hardware  compatible. Even though  8514/A is an IBM product , it isn’t  even slightly compatible with IBM’s earlier graphics standards , although it can work with a VGA board to provide additional graphics modes on the same monitor. The  resolution available on the current  version of 8514/A are :    

Ø  640 x 480 in 256  colourss  from a palette of 262, 144 and

Ø  1024 x 768 in 256 colourss from a  palette of 262,144

Other manufacturers have extended the standard by  using more than one  8514/A chip to  include higher resolutions up to:

Ø  1280 x 1024 with 24-bit colours

Another problem with 8514/A  is that is uses and interlaced  display and so is  prone  to flicker. Other manufacturers  have ignored  this part of the standard and there are 8514/A compatible graphics  cards and  monitors that  are non-interlaced.

Instead of expecting the programmer to use the hardware  directly , recall that the  hardware specification  hasn’t been  made public, IBM have  introduced  a software   interface – the  applications interface  or AI. At the moment only Microsoft  have deviated  from using the  AI. They have obtained  the hardware  specification from IBM under license  so that they  can write drivers  for windows that  go direct  to the hardware. The AI provides a software standard  that can be used by  other graphic boards to provide a  measure  of 8514/A compatibility.  It also allows IBM to change their  hardware any time  they need to  leave the competition behind.