RE: 5250 graphics

--
For what it's worth:
 /** Rant on **/
 The 5250 graphics orders were a "bolt on" to the original 5250 twinax 
data-stream. The terminal had to send back PF key scan codes after processing 
the orders (the technical reasons as I recall had to do with twinax timing 
requirements vs the technology available for raster-scan conversion). This 
added a fair amount of complexity to applications using the data stream.

 This may well have been a technology 'ahead of it's time', that got rushed 
into place to meet late breaking requirement in the S/36 Release 1 delivery. By 
the time the product hit the street the stand-alone terminal was on the order 
of $7K. The original PC 5250 emulation (and later DOS based PC Support and DOS 
CA) implementations required loading sizable drivers in DOS, that were VERY 
dependent on the display characteristics (for around $5K). And the resulting 
graphics (at least on the early PC displays) suffered the predictable 
"stairstep" effects, and were drawn relatively slowly (even with a then speedy 
80386). This support pre-dated SAA's definitions for a "common" set of graphic 
orders. If I remember correctly, Windows 3.0 and later incarnations came with 
faster graphic drawing capabilities (that might have made writing a terminal 
emulator easier, to say nothing of easier to set up and use).  The point is the 
memory requirements were big, and the setup difficult -- and you had a 320x680 
pel display(!!??). It might have been interesting to see what this could have 
done on a more graphic oriented personal workstation -- a MAC of the era comes 
to mind!

Despite several COMMON requirements, dating back to the first Win '95  and OS/2 
based terminal emulators IBM refused to make the investment needed to bring the 
S/38 and AS/400 GDDM support forward to more capable workstations. I suspect 
the GDDM host support has not progressed far beyond the GDDM V1 capability used 
on the S/38 CPF Release 6 (when it was originally released). The last time I 
looks (and this was several years ago) GDDM on TSO/VM/MVS was at version 4 or 5 
with some significant functional additions.

 I have heard that IBM plans to remove the 5250 graphics and drop GDDM support 
on the iSeries in a future release (as in very near future release).
 Pity -- the GDDM on the MVS/VM environments got so they could REALLY produce 
decent graphics.
 /** Rant off **/
 Using current GUI/HTML capabilities on PC's some outstanding graphics 
applications were (and still could be written) using GDDM -- if the link was in 
place.
 As it is, GDDM provides a reasonably usable (and device independent 
architecture) for an application to create decent graphics.
 I understand that there is a LINUX 5250 emulation -- it might be interesting 
to explore what it would take for that emulator to "crack" the 5250 graphics 
orders!


George Lemen
Strategic Solutions Inc. e-mail: george@strategicsol.com; phone (425) 462-6446
personal: georgelemen@seanet.com; cell phone (206) 419-6225

----------
From:   Steve Richter[SMTP:srichter@AutoCoder.com]
Reply To:       mi400@midrange.com
Sent:   Friday, November 02, 2001 12:25 PM
To:     mi400@midrange.com
Subject:        Re: [MI400] 5250 graphics

Jim, others:


The 5250 data stream has what looks to be a rich set of graphics orders.
GDDM is implemented using these orders.

Graphics orders are a very efficient way to transmit graphics to a display.
They are programmer friendly and device independent. Example orders:  Draw a
bar chart, place grid lines around a subfile listing, shade the top area of
the screen, gray the bottom half.

Display file DDS is a very good vehicle for coding graphics orders.

Telnet 5250 ( tn5250 ) is an open internet standard. It, along with tn3270,
look to be the most feature rich of the telnet specs ( by far ).

The iSeries is the best Telnet server on the market. ( also by far )

Telnet  has great connectivity options. You can client connect to the server
from dumb terminals, palm devices, and pc's.

I will stop now, because I am not selling anything.  My question had to do
with technical aspects of 5250 graphics orders.  But I dont think very
functional features should be written off so quickly.

-Steve Richter


----- Original Message -----
From: "Jim Langston" <jlangston@celsinc.com>
To: <mi400@midrange.com>
Sent: Friday, November 02, 2001 12:04 PM
Subject: RE: [MI400] 5250 graphics


Hmm.. for that matter, why couldn't you write your own API to
do graphics, which would change the way they were transmitted
dependant on what device the user was using?  If they were
using a GDDM capable device send the data that way, otherwise
send using IP socket to some VB client that would display them?

The answer, I think, is the same reason GDDM died, not much
need for it.

Regards,

Jim Langston

-----Original Message-----
From: thomas@inorbit.com [mailto:thomas@inorbit.com]
Sent: Thursday, November 01, 2001 7:28 PM
To: mi400@midrange.com
Subject: RE: [MI400] 5250 graphics


Njål:

On Thu, 01 November 2001, "Njål Fisketjøn" wrote:

> Why burden the AS/400 to "do" the graphics, when you can easily write
> a client server app to make the PC do it?
>
> And why bother learning "stone age" API's (GDDM), when you can use VB,
Java
> or some other PC-based language?

You're right in both respects. Yet, there are reasons for both. The
immediate simple responses that come to mind are that GDDM is available for
free on AS/400s all over the world and that MI has a difficult time calling
VB programs adequately. Also keep in mind that GDDM can be used to create
printed graphics; i.e., a 5292 graphics workstation is not required for
output.

Maybe the best reason of all for this list is simply... it feels pretty cool
when you make it work!

Tom Liotta

--
Tom Liotta
The PowerTech Group, Inc.
19426 68th Avenue South
Kent, WA 98032
Phone  253-872-7788
Fax  253-872-7904
http://www.400Security.com

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