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with 9K left spare, and while it can’t compare with a good 16K Basic, it is a lot better than the arbitary standard ‘8K Basic’.

Compatibility

XTAL Basic uses the minimum number of calls to monitor routines, and all these are made through a short table of jump instructions. This means that these are easily changed to cope with any monitor changes. The tape is issued with a Nasbug version recorded in Nascom 1 format on one side, and a NAS-SYS version recorded in Nascom 2 format on the other. However the manual describes how to change one version to the other, and this would only take a few minutes, and the changed version stored on your own tape. One criticism here is that the NAS-SYS version does not follow the NAS-SYS ‘rules’, and uses absolute jumps instead of the NAS-SYS restart instructions. However, this is easily corrected as shown in the tabulation of the jump table (below) which starts at 2BDDH. The tabulation shows the correct values for NAS-SYS, and ensures that upward compatibility is maintained.

T2BD8 2C00

Comparison of commands

XTAL Basic has the following extra commands:

EDIT This allows a program to be edited line by line. Characters can be changed, inserted and deleted. Users of ‘SUPER TINY BASIC’ will notice a resemblance to the MCE comand. The XTAL Basic does not support the convenient NAS-SYS editing, although this method does have the advantage of allowing long lines (about two lines on the screen). The cursor movement keys are not used in the same ways as in NAS-SYS or Nascom Basic. Also CS is used instead of ESC.

CSAVE & CLOAD are similar to the Nascom Basic but allow names of up to six characters. The CLOAD routine stops when the first error is encountered, so your cassette recorder must work well if you have long programs.

PRINT @ X,Y,​"ABC" prints ABC at the X,Y coordinate. This is similar to using the Nascom Basic SCREEN command, followed by a PRINT command.

POP Deletes the return of a GOSUB, so that an abnormal exit can easily be made from a subroutine.

SPEED up. Sets the output speed to allow the Basic display to be slowed up.