Video Generator Schematics Page 5
These modifications finish the wiring up of the character generator so that upper and lower case letters can be accessed. Note that special software is required to handle this, you don't just push the shift key on your keyboard! This mod also makes changes to the game controller port at J14 so that all sections operate properly and corrects a 1 bit video shift problem that the European Apple has. If you want to demonstrate this problem to yourself type "GR" and then "TEXT". The entire screen except for a few lines~at the bottom will show "G". If you look carefully at the right and left edges of the screen you will notice that one edge has 2 dots and the other has none. This modification will correct this problem and put one dot at each edge of the screen. Another problem that this mod corrects is an error in Apple's programming of the Auto-start monitor that causes improper initialization of the annunciators in the game controller port. This is normally not a serious problem but in the Euro-Apple it would cause it to initialize in the lower case mode on power-up.
Step 1) Cut all foils to/from the following pins:
A01-03 (Top) <--------- A01-04 (Top) <--------- A01-05 (Top)
A01-10 (Top) <--------- AO1-11 (Top) <--------- A01-12 (Top)
A01-14 (Top) <--------- F14-12 (Top)
Step 2) Remove the temporary connection from CGEN-19 TO A01-08.
Step 3) Gonnect the following jumpers with #30 wire:
FROM ---------- TO ---AND--- FROM -------- TO
A01-12 <-------> A03-08 --------- A01-11 <----> A03-07
A01-10 <-------> A03-06 --------- A01-05 <----> A03-05
A01-04 <-------> A03-04 --------- A01-03 <----> A01-14
F14-12 <-------> J14-12 --------- H14-01 <----> J14-04
F14-12 CGEN-19 Wire
A12-05 CGEN-22 Wire
A01-03 CGEN-15 Wire
Step 4) Change the 1K Ohm resistor, (R12), connected between F14-15 and +5 Volts to a 10K 1/4 Watt resistor. Connect a 10 uF 15 Volt capacitor from F14-15, (+ side), to F14-08, (-side). This step forces a power on reset of F14 so that when using the old monitor the character generator is initialized in the upper case only mode.
Step 5) Apple made an error in the program in the Autostart monitor ROM. This error causes the machine to Autostart in the Upper case + Lower case mode. On page 36 of the Apple Reference Manual they state that the Annunciators initialized as follows.
This is not true, in fact the exact opposite is true. AN3 must be fixed for the UC + LC mod to work properly. The other ones may be fixed if you desire. To fix this you will need an EPROM programmer or you will have to return the F8 ROM to me for reprogramming. tThat is the price you pay for taking the ROMs before I had checked everything out.) Please specify if you want just AN3 or all 4 fixed. The changes are all in the F8 ROM.
Again it is time to fire it up ard check your work. Get into Applesoft and type some junk on the screen and hit return a couple of times. Type in POKE -16289, 0 and the screen should change to lower case. Type POKE -16290,0 and it goes back to upper case. To display a combination of UC and LC characters on the screen at the same time you go to UC + LC mode (POKE -16289, O) and then store characters that are to be upper case as inverse video in the apple memory. Appendix 1 contains the article from which this mod was taken and it has more explanation including the instructions to modify the Apple Writer text editor for use with this modification. Be aware that there are some inconsistencies and innaccuracies in this article. You will probably be as confused as I was.