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keropi
May 16th, 2017, 11:19 AM
Hiya , yet another cross-post from VOGONS since EGA-knowledge is something rare these days...

I just purchased a Great Tek HRGPEGA EGA card but I was unable to find it's jumper settings - mainly what the J3 block does (under the 3 crystals) ... can anyone provide some insight on this? :confused:
I will pair it with a Hyundai HCM-1420 monitor I just got.

http://i.imgur.com/fWbiNPql.jpg (http://imgur.com/fWbiNPq)

http://i.imgur.com/fPwKSMkm.jpg (http://imgur.com/fPwKSMk) http://i.imgur.com/Y81Qk2Cm.jpg (http://imgur.com/Y81Qk2C)

http://i.imgur.com/bMyzTKJm.jpg (http://imgur.com/bMyzTKJ) http://i.imgur.com/8NCovYCm.jpg (http://imgur.com/8NCovYC)

I also would like to ask about the 2 RCA jacks, are they composite outputs? why 2 of them? :confused:

TIA for any help/tips/guesses!

Stone
May 16th, 2017, 11:50 AM
I also would like to ask about the 2 RCA jacks, are they composite outputs? why 2 of them? :confused:No, they are not composite outputs -- they are feature connectors.

keropi
May 16th, 2017, 11:57 AM
thanks for the info, I will pretend they don't exist then :p

lutiana
May 16th, 2017, 11:59 AM
No, they are not composite outputs -- they are feature connectors.

What features could be connected?

keropi
May 16th, 2017, 12:06 PM
^ from what I have read here (https://l.facebook.com/l.php?u=http%3A%2F%2Fwww.vcfed.org%2Fforum%2Fshowt hread.php%3F19005-EGA-RCA-output&h=ATPKhmBdapjJ9Au3IcGlIvv4HI80ld9JU8twhat40_eXHdUU 9enJ-wjefo2Gv0yK_y-B3bsDwKRr-JdpYk8Blq18pJHskAWsvLQRvuFVY0QeFMQOAgYV855_m-Xa849s3iDIg74): nothing :rolleyes:

krebizfan
May 16th, 2017, 12:11 PM
What features could be connected?

The only things that plugged into the feature connector were alternate clock generators on a card. Nothing used the RCA jacks. Or, if something did, I don't know of it.

modem7
May 16th, 2017, 02:27 PM
Generally, the feature connector setup is per the IBM EGA diagram at [here (http://minuszerodegrees.net/video/ibm_ega_card_feature_connector.jpg)].

Some EGA cards can output composite video on one of the RCA connectors. The EGA Wonder (manual at [here (http://minuszerodegrees.net/manuals.htm#ATI)]) is an example.

lutiana
May 16th, 2017, 05:25 PM
The only things that plugged into the feature connector were alternate clock generators on a card. Nothing used the RCA jacks. Or, if something did, I don't know of it.


And why would you want to use an alternate clock generator?

pcdata76
May 17th, 2017, 12:11 AM
And why would you want to use an alternate clock generator?

To be able to use higher resolution modes (like 120-column text mode) https://books.google.com.tr/books?id=vcqI6sY2e-kC&pg=PA298&lpg=PA298&dq=ega+external+crystal+resolution&source=bl&ots=5YjdwPAyLa&sig=d64f60RYXj3pxYZMzl_Cy7sOPm8&hl=tr&sa=X&ved=0ahUKEwjq8JHduvbTAhUDlCwKHYqbDP4Q6AEIKTAA#v=on epage&q=ega%20external%20crystal%20resolution&f=false

Another good use of the feature connector is the composite video generator circuit which can be easily built even on a prototype board to interface a composite monitor (as in the case with IBM 5155's internal amber monitor) to the EGA card.

keropi
June 1st, 2017, 05:38 AM
I received the card but the jumper settings are still a mystery:


http://i.imgur.com/48TWqIQl.jpg (http://imgur.com/48TWqIQ)

http://i.imgur.com/w1vXNBll.jpg (http://imgur.com/w1vXNBl)


- J2 under the BIOS
- J3 block under the 3 crystals
- J4 under J3

A really wild guess is that J2 is used for selecting the card's address range?

I was able to figure out the DIP SWITCH block using the info in this thread: http://www.vcfed.org/forum/showthread.php?23047-Paradise-WD-EGA-cards , I had to put SW5 to OFF else my 286 would not boot - it would hang with a blinking underscore (SW5 is monitor "auto configure")

It would be nice to know what the rest of the jumpers did, maybe it's something interesting/useful :confused: