NEED HELP USING THE BBC BASIC ASSEMBLER

[jrybak]

i have BBC BASIC for SDL 2.0 installed and it runs regular BBC BASIC programs just fine. However, I also want to run the BBC BASIC Assembler. When I try running the following:

10 REM
20 REM *SIMPLE ASSEMBLY PROGRAM*
30 REM
40 MODE 7
50 LET Start_of_Program =&3000
60 LET Output_letter =ASC("A")
70 LET Screen_start =HIMEM
80 LET Offset =250
90 REM
100 LET P% = Start_of_program
110 [ OPT3
120 .Prog LDA #Output_letter
130 STA Screen_start + Offset
140 RTS
150 ]
160 REM
170 INPUT" press return "A$
180 CALL Start-of-program
190 END

I get syntax errors on everything after line 90. Does BBCSDL not support use of the BBC Assembler? What about BBC BASIC for Windows?

Thanks for any help you can provide.

[David Williams]

Those assembly language mnemonics (LDA, STA, RTS) look like 6502 (8-bit) microprocessor instructions, so they are only meaningful if being processed by a 6502 CPU (like the one in a BBC Micro). BBC BASIC for SDL2.0 runs on several platforms (powered by 32-bit and 64-bit Intel and ARM CPU architectures), but certainly not on any 6502-based platforms. For instance, the Raspberry Pi versions of BBC BASIC for SDL2.0 run on 32-bit and 64-bit ARM architectures, and so they feature assemblers capable of compiling assembly language for those two architectures (32-bit and 64-bit ARM instruction sets are actually very different to each other). BBC BASIC for Windows only runs on Intel/AMD-based systems (using Intel's 32-bit x86 instruction set architectures), and so it features an assembler capable of assembling the Intel x86 instruction set. I don't know which version of BBC BASIC for SDL2.0 you're using, but it cannot assemble 6502 CPU instructions. That program you listed is for a BBC Micro.

[jrybak]

Thank you very much for clearing this up for me.

[nvingo]

I have BeebEm (BBC Micro emulator for Windows) installed and after cleaning up the inconsistencies in the program's format in Windows Notepad I was able to paste it into BeebEm and successfully run it.

[KenDown]

I presume that you are aware that the word LET is redundant?

x%=4

is identical in funtion to

LET x%=4

but uses an extra byte. Its sole purpose is that some people find it easier to understand if the assignment is spelled out in full.

[Hated Moron]

I presume that you are aware that the word LET is redundant?

LET may be "redundant" but some people prefer it for clarity and I don't think its use should be discouraged. On a simple measurement here adding the LET actually results in the code running faster:

Code: Select all

      TIME = 0
      FOR I% = 1 TO 10000000
        a = PI
      NEXT
      PRINT TIME

      TIME = 0
      FOR I% = 1 TO 10000000
        LET a = PI
      NEXT
      PRINT TIME

YMMV.