Unique to IBM Keyboard
Before the world moved to using PCs as the main interface to talk to the 400, we had IBM Keyboards with keys that are now largely disappeared from the keyboards of today.
Note that on PC keyboards the ESCAPE key usually does the same stuff as the Attention Key did on IBM keyboards.
This key by itself takes us to a menu that can be designated by our user profile.
Upper shift and this key gets you to the System Request Menu.
This meant DUPLICATION key. We have keyed in something on some screen, and we get to the same identical screen for another entry. Pressing the *DUP key on a field meant "Duplicate here an exact copy of what we keyed on this same field for our last entry."
ERASE INPUT KEY
This key erases 100% of the input on the current screen.
ERROR RESET KEY
There's various things that can go wrong when keying ... if you see a flashing # on screen and keyboard locked up, this is a safety mechanism to stop accepting input until after you do error reset.
If your keyboard is setup for keyahead, you might not want keystrokes acceepted after error detection.
Note that any time you see some error code on screen, you can cursor on it then F1 for more info.
Now people need to remember to use the universal F1 help key.
Hex here does not mean Witchcraft but Hexadecimal which is IBM name for Base 16 that Midrange computers used to run on (it might be a higher one now). This means that while humans count from 1 to 10, the 400 counts from 1 to 15 where the single character representing 10-15 is A-F.
Note that the world today now has two standards for how characters are represented.
- ASCII standard developed by IEEE and became standard in communications then was adopted by the micro computer industry.
- EBCDIC standard developed by IBM from Herman Hollerith inventioh.
Each byte is represented by a pair of hexadecimal characters, such as
- letter B upper case represented by blank then B
- letter b lower case represented by 8 then 2
Since 16 x 16 combinations comes to more than all the letters digits and special characters we are familiar with on most keyboards, there are a bunch more characters made available, which got used for such things as currency symbols around the world, and characters in some languages with a marking on top to give it an accent.
There were some intermediate keyboards where we had to use ALT then some key to get the HEX.
So to get at some character not on our keyboard, we would press the HEX key then the two characters in sequence that mapped that hexadecimal representation. One of the RPG manuals has a reference chart in an appendix showing all these characters.
Several keys common to PC keyboards have special purposes or roles in the 400 world.
IBM Keyboards had function keys F1 thru F24 and most 400 software uses all of those keys.
Most PC Keyboards only have function keys F1 thru F12. Typically we get F13 thru F24 by using upper shift vs. the F1 to F12 keys. It helps to have something on your keyboard to remind you which is which.
Within 400 certain keys have standard significance. This convention is often found in many 400 application packages.
- F1 Help
- Cursor sensitive ... the help you get is often related to where the cursor placement right before F1
- F3 Exit a program
- F4 Prompt
- Cursor sensitive ... the help you get is directly related to where the cursor was right be fore F4
- F5 Refresh
- You working on some screen ... this resets the screen to what ought to be there when you first get to that screen
- If you had keyed something in, you lose that.
- Original values restored
- F12 Cancel ... back up one screen
- F24 more function keys
- Typically a limited amount of space at bottom of screen is allocated for info about what each function key can do.
- F24 pages you through the explanations if all of them not fit into that space.