Commodore VIC-20: Cardco "Cardkey 1" numeric keypad
15A quick look at the Cardco CK/1 numeric keypad for the VIC-20 and C-64.
It plugs in via a DE-9 plug to the controller/joystick port and requires a software driver to function, meaning it can't be used with cartridge or protected software ... unless you have also the CK/1A Keypad Adaptor that is installed internally and mimics the relevant keys on the keyboard.
One neat use for the keypad is when typing in program listings with long DATA statements (i.e. used for loading machine code routines as part of a BASIC program) ... you can redefine one of the keys to print "DATA " and another for a comma. Then you can bash out the DATA lines pretty quickly.
It appears that the software was originally delivered on tape, however mine came with a double sided disk ... Commodore on one side and Atari on the other.
At the moment it seems that the CALC-VIC program is lost to time ... but if my disk works, and I get a working disk drive, then maybe I can recover it ... ?
Very well written manual:
https://www.vic-20.it/wp-content/uploads/2021/05/Cardco-Cardkey-User-Manual.pdf
KBASIC disk image (no CALC programs):
http://www.commodoreserver.com/PublicDiskDetails.asp?DID=05233DF6294C4791B78A7B6EC80F93A0
Forum discussion:
https://www.lemon64.com/forum/viewtopic.php?t=28802
Some more info on Rick Melick's various pages - big thanks to him for rescuing various Cardco driver software:
https://web.archive.org/web/20110910131000/http://rickmelick.org/kbasic-vic.html
https://rick-melick.blogspot.com/2013/01/impossible-to-find.html
http://www.geocities.ws/cbm/