biged_bbcmicro_basic_FIX_vc3-2022
Author: BigEd
Category: Christmas Challenge
System: Acorn BBC Micro
Language: BASIC (BBC Basic version 2)
Len source code: 63
Len exe file: 58
Len code only: not applicable
Instructions:
Visit owlet with a recent browser using this URL
https://bbcmic.ro/#%7B%22v%22%3A1%2C%22program%22%3A%221F.I%3D-4TO4%3AF.J%3D9-ABSI%20TO17%2BABSI%3AV.31%2CJ%2C13%2BI%2C42%2C31%2C13%2BI%2CJ%2C42%3AN.%2C%22%7D
OR
Visit jsbeeb with a recent browser using this URL
https://bbc.godbolt.org/
From the menu, choose "Discs" and then "From Examples or Local"
Select "Choose File"
In your file chooser find and select "bigedbas.ssd"
From the "Reset" menu, press and hold your Shift key and select "Soft Reset"
OR
With any emulator which supports the SSD format, load the SSD as disk 0 and shift-break the emulated machine to autoboot from the disk.
Description:
Oops - this is a fixed version as the submitted version had an error
Two nested loops, each iteration prints two asterisks, one for the current row and one for the current column, using TAB(X,Y) feature but using VDU codes for density.
In expanded form it would look like this:
10 FOR I=-4 TO 4
20 FOR J=9-ABSI TO 17+ABSI
30 PRINT TAB(J,13+I); "*"
40 PRINT TAB(13+I,J); "*"
50 NEXT J
60 NEXT I
Comments:
The program ends and Basic prints the ">" prompt which is a bit ugly, but it matches the rules which allow a "READY" prompt.
For the cost of two bytes we could append ":RUN" and avoid the prompt.