Acorn A4

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The laptop with its mouse.

What's in the box? The BBC Basic

I got it to satisfy my curiosity about the RISC OS world that I didn't know at all!

What's in the box?
  1. A CPU Risc ARM at 24MHz
  2. Risc OS 3.1 system in ROM
  3. 4MB RAM
  4. 640x480 in 16 greys or 16 colors on an external monitor
  5. serial, parallel, PS/2 keyboard, BUS mouse, sound ports
  6. Hard drive 82MB
Rear view with an unusual DB9 connector for the power supply.


The desktop with the BogoMIPS result.

To comapre, a TT/68030 at 32MHz gives 7,92.

With a simple proportion, an ARM at 32MHz would be:
9,53 x 32 / 24 = 12,71 that is +60% of power compared to a CISC Motorola processor with the same frequency.

Note the support for PC and Atari disk formats!


BBC Basic


To run the BBC Basic, you must open the task window and type *BASIC. But this task can be automated!

On my disk unit IDEDisc4, I created a folder named BASIC in witch I will save my programs. I'm going to create a command file (BATCH) to run the BASIC with a double clic. Firts, run the EDIT application, and, on its icon in the task bar, clic on the middle button to open the menu. Select "CREATE" and "COMMAND". This opens an edition window.
There you type the following lines:
  • the command DIR sets the default folder to the one I created: BASIC
  • the command FIX 202 switches CapsLock On because the BASIC is case sensitive!
  • last, the command BASIC runs the interpretor.
Finally, F3 opens the SAVE box and give the name RunBASIC to the command file and drag/drop its icon to the BASIC folder.
You can edit your programs directly from the command line using line numbers. But, better, you can use the EDIT application selecting "CREATE" and "BASIC". Here is my first program! It computes an approximation of PI using the sum of 1/n².

Note the first line, REM >... This allows you to save the program in the specified folder with SAVE without retyping its name each time.
There you see the file organization, my BASIC folder with the command files and the basic programs.

Note the file RunBASIC64! This runs the Basic 64, an evolution of the BASIC bringing a better precision in floating point calculations: the old 5 bytes format is replaced with the standard 8 bytes IEEE format.

To run the Basic64, you'll have to create a separate command file, similar to the other, but replacing the line "BASIC" with "SYSTEM:MODULES.BASIC64" and that's all!


Some results for this test (all with interpreted language):

(The index on the last line is an attempt to compare machines beyond their frequency, precision and execution time)

Machine Acorn A4/24MHz Acorn A4/24MHz MegaSTE 16MHz MegaSTE 16MHz+FPU Atari TT 48MHz+FPU Tosh286 12MHz+FPU Tosh286 12MHz+FPU FalconCT60 100MHz
Software Basic64 Basic Forth no FPU Forth + FPU Forth + FPU Qbasic + FPU Qbasic + FPU Forth + FPU
bits/number 64 40 64 64 64 32 64 64
PI (100000 iter) 3,1415831 3,1415831 3.141583104 3.141583104 3.141583104 3.141583 3.141583104 3.141583104
Time (sec) 21.09 4,25 46,96 16,01 4,25 20,59 21,20 1,79
Index
100*bits/sec/MHz
12,64
39,22
8,52
24,98
31,37
12,95
25,16
35,75


Since december 15th 2007