Informationen zu den Unterschieden zwischen XT- und AT-Modus
This article refers to:
All CHERRY keyboards
Description:
When IBM launched its XT 8086 and XT 8088 series PCs, there was only one specification in existence - for IBM XT keyboards. These XT keyboards only recognised the so-called Set1 scan code. To differentiate between the make code (also known as the downcode = key code when the key is pressed) and the break code (also known as the upcode = key code when key is released) 80hex was simply added to the make code.
A new keyboard specification was created when IBM launched its AT 80286 and AT 80x86 series
AT keyboards then became the standard in the so-called Set 2 mode.
The break code then (usually) consisted of F0 and the associated make code. AT keyboards thus support Set1 of "old" XT keyboards and Set2 and Set3 of the new AT generation.
Following the move to AT keyboards CHERRY provided most keyboards with a switch allowing an AT keyboard to be turned into an XT keyboard. This means that the AT keyboard behaves like an XT keyboard with the appropriate switch setting. After the PC is started up, the system reports an XT keyboard and uses Set1 codes by default.
As PC-XT computers have become scarce on the market in recent years and the demand for switchable keyboards has all but disappeared, CHERRY has decided to discontinue fitting the converter switch on its newer product lines. Should you nevertheless require an XT-compatible keyboard, please contact your dealer or the CHERRY Hotline.
Examples:
The keyboards in the G8x-1800 xxx (3-letter version) series up to production code I27 (until 8 July 1996) still had an XT/AT converter switch.
On the other hand, after this date the keyboards in the G8x-1800 xxxxx (5-letter version) series are AT keyboards only. Conversion of these keyboards is not possible!
select language: 
