Star2
Author: FlaxCottage / StarDot Forum
Category: Christmas Challenge
System: BBC micro
Language: BASIC
Len source code: 110
Len exe file: 110
Len code only: 110
Instructions:
This is designed to run with the BBC micro emulator BeebEm. Start BeebEm and use File-->Load Disc 0 and choose the file Star22.ssd.
The disc is set to autoboot. Hold down the Shift key and at the same time press and release F12 (the Break key emulation). The file 'Star2' on the disc, the program which draws the star, will load and run.
Alternatively the command CHAIN"STAR2" will load and run the program.
Description:
The star is symmetrical. Its shape uses a simple arithmetic progression to draw the asterisks.
A FOR ... NEXT loop executes six times, running from 0 to 5. Within this loop the string A$ is set to a decreasing length of asterisks, starting with a length of 17 and decreasing by 2 each time the loop runs. A$ is printed repeatedly to give the body of the star down to the narrowest line in the middle. The TAB(x,y) function is used to position the line of asterisks in the correct place on the screen, moving down and up from the widest point to the narrowest.
The upper and lower points are printed in a similar fashion within the loop for the loop counter in the range 0 - 3. In this case a string B$ is assigned as an increasing number of asterisks either side of a decreasing number of spaces. These run from one asterisk each side of seven spaces to four asterisks each side of one space. These points are printed from top and bottom alternately and are inset four spaces in from the left.
Comments:
This program will run on any computer able to run BBC BASIC version 2 and above. The submitted disc image runs in MODE6, however, it will run in any MODE available.
The disc image, Star22.ssd, can be loaded into a real computer in a variety of ways;
1. Attach a GOTEK floppy drive emulator and load the file from a USB memory stick,
2. *IMPORT STAR22.ssd from a USB memory stick into the RAM disc of a Retroclinic Datacentre and run the disc image from there,
3. Use MMBimager.exe on a PC to copy the disc image into a vacant drive slot in the MMB container on an SD/MMC card that runs under MMFS,
4. Use OmniFlop on a compatible PC (having a real FDD interface and running Windows XP) to write the disc image to a real floppy disc (either 3.5" or 5.25"),
5. Use BeebEm to LIST the program to a printer file. Rename the printer file as STAR.TXT. Copy this file onto a formatted 3.5" PC format disc. Use an A3020, A4000, A5000 to *EXEC the file from the disc and copy this file onto an Econet. The saved file can then be CHAINed normally.
The program has been tested on a BBC micro, BBC B+, BBC Master, A3000, A3010, A3020, A4000, A5000 and a Raspberry Pi running RISCOS or RISCOS-pico. It is also second processor compatible.