Actually the line editor will refuse you to enter a line which is more than 88 characters (exact four screen lines). Here are some (but not all) addresses the cartridge may "hijack" while running in 40 or 80 column mode:
LXSP $00C9-00CA (201-202)
Cursor X-Y (line-column) position at start of input
PNT $00D1-00D2 (209-210)
Pointer: Current screen line address
PNTR $00D3 (211)
Cursor column on current line, including wrap-round lines, if any
LNMX $00D5 (213)
Current logical line length: 21, 43, 65 or 87 (VIC)
TBLX $00D6 (214)
Current screen line number of cursor
LDTB1 $00D9-00F2 (217-242)
Sceen line link table/Editor temporaries
USER $00F3-00F4 (243-244)
Pointer: Current colour RAM location
HIBASE $0288 (648)
High byte of screen memory address
IMAIN $0302-0303 (770-771)
Vector: Indirect entry to BASIC input line and decode
IGONE $0308-0309 (776-777)
Vector: Indirect entry to BASIC character dispatch routine
IBSOUT $0326-0327 (806-807)
Vector: Indirect entry to kernel CHROUT routine
Based on what you've mentioned, I would say that at least LNMX, LDTB1, HIBASE and IBSOUT are different from normal. If the IBSOUT routine doesn't bother to update LNMX and LDTB1 when a wrap-around occurs, it is rather obvious if Basic gives you ?SYNTAX ERROR when trying to store the line which you thought was kept together but which wasn't.
The screen link table (26 bytes? in LDTB1) is rather funny to play with. Right now I can't recall exactly how it works, but messing up some of the pointers there can yield interesting results when scrolling the cursor. Don't have an important program loaded though.
From what I gather, the company was "Data 20". In the Cartlist, both a Display Manager and a Video Pak are listed as 40/80 column devices. The one Chris bought was the Display Manager, but I don't know if there was two different or just popular names on the same unit.
If the IBSOUT routine doesn't bother to update LNMX and LDTB1 when a wrap-around occurs, it is rather obvious if Basic gives you ?SYNTAX ERROR when trying to store the line which you thought was kept together but which wasn't.
You hit that one on the head.
It is also funny to write a line in 80 column mode, and if say the 41st entry is a number, and then you switch back to 40 column mode, and then run the program, eveyrhting is fine, but if you list first, it will see the 41st entry as a new line number.
well, i finally hooked up a vic with the 40 column cart. to a monitor, and at the same time, hooked the video out from the vic to a tv, so i could see what would happen.
i turned on the vic, and the monitor displayed in 40 columns and the tv had the proper border and screen colours but no text at all.
no matter what i did (besides using pokes)., i could not get text to appear on the tv, yet the text appeared on the monitor.
i then poked chartacters to the screen and played around poking different colours, and the tv then displayed the proper characters and colours, but no change to what was dsiplayed on the monitor.
i could also change the screen colour via pokes.
it's too bad, but i think that the super expander cart. and the display manager cart. would conflict, because i would love to know if i could display graphics on one screen and at the same time have text on the other screen, and be able to manipulate them without affecting the other screen.
so, i am now thinking i have an interesting split screen ability with this setup.
i would like to try it with the light pen too, as i can have one screen display symbols or whatever for locating with the light pen, and then use the other screen to display the results of whatever actions.
You wrote that there was a SYS to turn it off, is there a SYS to turn it on too, so you could use PRINT to the regular screen from within your programs?
Super Expander would surely conflict as it seems to locate partially in the same place as this cart. However, you could get another hires drawing kit which will not be as powerful as the Expander but operate in another part of the memory.
I'm thinking something like moving Basic to $2000, using the low 1K for video memory and maybe hires routines and have the 40/80 cartridge occupy all the high parts of memory. To make the software more compatible for us others, the 40/80 output could be selectable to appear on screen or printer.
thanks for reminding me Anders, about the SYS commands, as i forgot about them.
yep, i can switch from one display to the other, with the proper command.
i wrote a quick program that lets me switch back and forth and write to the screens.
weird going back and forth from colour and big letters, to black and white and small letters, so i would like to make the vic display for graphics, and leave the 40 coulumn to do the text.
i will look for alternative drawing kits then, as i would like to play around with the two displays, and see what i can do.
I have a rather short one which plots points and draws lines on a 128x128 bitmap. It may be possible to extend to use a bigger display and still have room for a 256 byte video matrix at $1F00 (7936). Which aspect ratio would you prefer of these?
one thing that i have been enjoying is using two screens at once, and i am trying to incorporate text on one screen and hires graphics on the other.
this has been really handy when using custom characters as well.
no worries about remapping standard characters and all that, as i just look at my code on one screen (driven by the 40 column cart. and is unaffected by moving the pointer for where charcaters are stored) and watch the effects on the other screen.
mind you, some interesting quirks can be seen on the screen receiving signals directly from the vic, once you start adding memory and start poking around.
and for anyone who has this cart. try using it in combination with the porg. aid cart. and hit F3 (IIRC).
you can get the 40 column screen to jump into a 30 x 9 screen and other crazy things!
Hi, I too have a DATA-20 40/80 column cart (I'm located in Cornwall, Ontario - near you!). I think I was discussing this with you in another thread.
Anyway, when I turned it on it totally brought me back to those 40 column PET computers I used to play around with in elementary school! (I had a PET a few years ago but had to sell it because of space considerations - and general lack of use ).
I just wanted to say that with my DATA-20 board, pressing the F5 and F7 keys toggles between 40 and 80 column mode automatically.
Also, pressing SHIFT in combination with the F1 or F7 key toggles between upper and lower case.
Would love to get a scan of your 'manual' as otherwise I don't know how to use this board.
I was also intrigued to read that your manual states you needed to type a SYS command to use the 16K RAM expansion. I tried plugging my board into a multi-slot expander the yesterday with a 16K expander and it the RAM showed up. But I didn't try playing around or loading anything.
yep i have the same type of card as you, from data20 and with their opening screen.
if you want to do a ROM dump for anders, that would be sweet.
i will supply you with a scan of the manual, but i do have to warn you that my copy is really hard to read.
i think i was starting to trancribe it to a text file for leif (schema) who also has a 40/80 card, but he managed to get a better copy of the manual i think
Hm, so you have a manual. What were we going to do with the ROM dump, other than archive it in case someone can build a compatible board? We were trying to find which pointers or calls it patches, but that was only to find which area of memory it was worth dumping.
yep i have the same type of card as you, from data20 and with their opening screen.
chris
Thanks for offering a scan of the manual. That would be very helpful! I suppose you could post a link here, or e-mail it to me privately at the e-mail address I supplied to you in the PM. Looking forward to it!
