Right arrow for the VIDEX patches................Mike Laumer

The VIDEX 80 column board patches for the S-C Macro Assembler in last months Apple Assembly Line was a welcome article for me.  You see I bought a VIDEX board last November but have no software to run it.  I've been planning to write a program development editor similar to the one I used at Texas Instruments, but so far I haven't had the time between the FLASH! compiler, MIKE'S MAGIC MATRIX and the American Heart association CPR Training system.

The patches were very usable, but a major problem still existed to prevent my use on a regular basis.  The right arrow key would not copy characters from the VIDEX screen.  Try to copy a file name from your catalog with that limitation!

I knew it could be done, because the VIDEX software in ROM has to do that function.  Don Taylor mentioned last month that he didnt know the right routine to call and his ROM differed from the listing in the VIDEX manual.  My listing was a little off also from my ROM, but I didn't care becase I wasn't going to call the ROM routines.

I used the VIDEX manual's listings to locate the section that performed the copy-character-from-screen function and used similar code in the RDKEY routine of last month's VIDEX patches for the Macro assembler.  The 'BNE' to '.3' was changed to go to 'CTRLU' and the copy function coded to process the right arrow key for the VIDEX 80 column board.

I needed two temporary variables to save the X- and Y- registers, so I used the first two bytes of the normal Apple text screen at $400 and $401.  Another temporary variable is at $402.  Since the normal Apple text display is not operative while the VIDEX is enabled you can use it for temporary variable space without it affecting the screen display.  If you try a trick like this some time, you must be careful because some of the monitor routines like HOME and SCROLL can easily zap your storage when you least expect it.

With this new capability of the right arrow key functioning as expected, I am able to use the VIDEX patches often in my software development work.  But there are a few problems left yet to solve that I didn't get to look into before writing this article.  They are:

!lm+9
!pp-4
1.  A RETURN key should clear to the end of line on line input, but not EDIT input.

2.  The control character display features are not handled very well by the VIDEX patches.

3.  The patches blow up on Reset.  (I think.)

4.  The patches blow up on INT or FP commands.
!np
5.  The patches don't work very well when you use MNTR command.

6.  All calls to $FC9C (the Monitor clear to end of line routine) should send $9D to the VIDEX board.

7.  Right arrow, left arrow, and any printing key cause the entire EDIT line to be redisplayed.  The flicker is somewhat annoying.
!pp0
!lm-5

The listing that follows should replace lines 4020 through 4420 of the listing on pages 21 and 22 of the August 1982 issue.

The source code on the AAL Quarterly Disk #8 will have these lines already merged with Don Taylor's patches.
