The original prototype 8K BASIC keyboard
released as an upgrade for the ZX80 to a selected beta test team.
Launched at the PCW Show in 1980, it was quickly withdrawn to
incorporate the ZX Printer commands
- see lower illustration.
Careful study shows a space in the GO TO and GO SUB keywords.
The new square
root function has the FORTH token SQRT instead of the BASIC keyword SQR.
READ, DATA and RESTORE were there.
Also DRAW which was removed although the
BASIC algorithm appeared in the ZX81 manual.
It was suggested that the user
develop a BASIC UNDRAW subroutine but here is the UNDRAW command on the
original ZX81 keyboard.