IBM Programmed Symbols Adapter

From: Philip.Belben_at_powertech.co.uk <(Philip.Belben_at_powertech.co.uk)>
Date: Thu Apr 15 11:27:15 1999

Larry Walker wrote:


> Muellers 3rd edition mentions 3 to 6 custom cards. You also required the
> 3270PC keyboard and the 5272 monitor which allegedly was comparable to an
> EGA. Other than that it was a stock XT M-B


5272 was 720 * 350 pixels, like an EGA, but only 8 colours. I seem to remember
reading recently that the 3270-PC could use the IBM monochrome display instead
(which presumably meant that it emulated a 3278 instead of a 3279)


> He outlines the boards which are
>
> 1. 3270 System Adapter- to connect to a remote 3274 controller
>
> 2. Display Adapter- extended-character in 8 colors
>
> 3. Extended Graphics Adapter for local graphics in Hi (2colorsat 720x350 or
> 640x200) and med. (4 colors at 360x350 or 320x200) IBM called this an XGA
> not the same as the PS2 Extended Graphics ARRAY.


Interesting. It seems that IBM terminology is not only different from both
American and British dialects of our language, but internally different on the
too sides of the Atlantic too. At IBM Bristol, this was _always_ called the APA
card.


> 4. Programmed Symbols Adapter to provide graphics capabilities available on
> 3278/3279 display stations. Needed the XGA in an adjacent slot. Joes' card.


Needed the XGA in an adjacent slot? Ouch! I had always assumed that you could
have just this and the display adaptor, but I admit to having no evidence to
back this up.


> 5. Keyboard Adapter - went in the 8th slot and connected the special K-B.
>
> On delivery the XT slots in the 3270PC were filled with the Sys adapter, the
> display adapter,K-B adapter, FDD adapter, and HDD controller. With the graphic
> adapter and memory multifunction card not much room left.
> Interestingly the 3270PC Control Program allowed up to 7 windows at one time.
> Shades of things to come. Apparently there was also an AT version.


I'd forgotten that the keyboard adaptor was a separate card. IIRC, it came with
a special cable that linked it to the keyboard and to the keyboard port of the
XT.

The keyboard, as well as having 24 function keys instead of the XT's usual 10,
had keys like "jump" to move between windows. These keys were intercepted by
the keyboard adapter and _not_ passed on to the keyboard port on the
motherboard. I think the card also locked out the motherboard KB port totally
when it was being a terminal.

Software did exist for talking to the host, looking at the terminal's screen and
file transfer under PC program control, but none of it was very easy to use. (I
had to program around it.)

Philip.





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Received on Thu Apr 15 1999 - 11:27:15 BST