{"id":605,"date":"2021-09-18T18:59:20","date_gmt":"2021-09-18T16:59:20","guid":{"rendered":"https:\/\/automatico.freevar.com\/?page_id=605"},"modified":"2021-10-05T18:15:58","modified_gmt":"2021-10-05T16:15:58","slug":"bbc-basic","status":"publish","type":"page","link":"https:\/\/automatico.freevar.com\/index.php\/cp-m-80-2\/bbc-basic\/","title":{"rendered":"BBCBasic"},"content":{"rendered":"

It is probably the most popular BASIC version for the 8 bits you can find, there are also versions for Mac and Windows.\u00a0A search on the net will satisfy much more than four lines written by me.\u00a0Why am I presenting it?\u00a0Because I found the assembler sources in<\/span> https:\/\/github.com\/jblang\/bbcbasic-z80<\/a> and I couldn’t resist modifying them to have a BBCBasic version with customized graphic (and audio) instructions for Fabgl’s VT100 video and ESP32 graphic terminal .<\/span><\/p>\n

The manual is online at https:\/\/www.bbcbasic.co.uk\/bbcbasic\/mancpm\/index.html<\/a> or you can find it here in pdf format \u00a0BBCBASIC(Z80) Manual<\/a> .<\/span><\/p>\n

The BBCBasic version I downloaded is generic for CP \/ M and the graphic and sound instructions have been disabled.\u00a0BASIC is an imperative programming language and certainly does not allow program structuring but\u00a0BBCBasic is a dialect that\u00a0<\/span>\u00a0supports named procedures, local variables, recursion and other structured programming features.\u00a0Unlike Microsoft BASIC, you can write structured programs without having to refer to any line numbers.\u00a0For example, let’s see the classic calculation of the factorial:<\/span><\/p>\n

\r\n10 PRINT FNfattoriale(5)\r\n20 END\r\n30 :\r\n40 DEF FNfattoriale(N)\r\n50 IF N=0 OR N=1 THEN =1\r\n60 =FNfattoriale(N-1)*N\r\n\r\n<\/pre>\n
Note that line numbers are present to sort the instruction list but are not needed to control the flow of instruction execution.<\/span><\/span><\/p>\n
The changes I have made currently are:<\/span><\/p>\n
MODE 0 | 1: text screen |\u00a0graphic screen.\u00a0The text screen is 80 columns by 24 lines and color characters.\u00a0The graphic extension is rigid and is fixed at 640 horizontal points by 480 vertical points.<\/span><\/p>\n
CLG: Screen cleaning in graphics mode.<\/span><\/p>\n
GCOL R, G, B: color setting of the dot or line indicating the intensity of red, green and blue.<\/span><\/p>\n
PLOT X, Y: lights up a colored dot in the graphic screen (see GLC).<\/span><\/p>\n
DRAW X1, Y1, X2, Y2: draws a colored line between the coordinate pairs.<\/span><\/p>\n
MOVE X, Y: scrolls x columns and y rows on a graphic page.<\/span><\/p>\n
SOUND TYPE, FREQUENCY, DURATION,\u00a0VOLUME:\u00a0emits a sound of type 0-sine 1-square 2-triangle 3-sawtooth 4-noise 5-vic noise, of frequency in Hertz, duration in milliseconds and volume between 0 and 127<\/span><\/p>\n
The BBCBasic program can be found here <\/span>https:\/\/automatico.freevar.com\/dump\/bbcbasic.com<\/span><\/a><\/p>\n
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It is probably the most popular BASIC version for the 8 bits you can find, there are also versions for Mac and Windows.\u00a0A search on the net will satisfy much more than four lines written by me.\u00a0Why am I presenting it?\u00a0Because I found the assembler sources in https:\/\/github.com\/jblang\/bbcbasic-z80 and I couldn’t resist modifying them to […]<\/p>\n
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