3 Jan
2012
3 Jan
'12
12:39 p.m.
In genral,
BASICs were not extendable like that. It is very difficult to
add new keywords ot a BASIC interpretter, and the way to do it is not
often docuemnted.
MICROS~1 BASIC typically has a somewhat awkward DEFUSR function in the
language to let you create and call machine language code. If you can find them, there are commercial packages of machine
language functions
for common tasks. Such as Brett Salter's "Peeks and Pokes".
On platforms with appropriate hardware (such as Coco, and even 5150),
MICROS~1 BASIC usually provided a usable set of graphics primitives, built
into their BASIC!, consisting of set-a-pixel and read-a-pixel, with some
minimal extensions, such as line draw.
Of course. the problem comes when you ad/chnage this hardware.
If I take my IBM5150 and interfce it to an I2S image proccessor/display
system then there's no easy way to add functions to M$ BASIC to cotnrol
it (OK, you cna use the USR function, but it's a kludge). But I could
write a library of functions in C and clal them from my C progrmas
without any difficulty.
-tony