[Coco] Why so little mem for 4K Coco

[Darren A]

On Thu, Jan 1, 2015 at 12:02 AM, Jim Gerrie wrote:

> Can someone tell me why the 4K Coco 1 only boots with 2542 bytes available?
> My 4K MC-10 boots with 3142 bytes available.  Is there any way to get a
> little more mem (besides clear 1)?  I have another 4K game (tetris) that
> will fit my MC-10 but not the Coco.
>


The MC-10 actually has 4K + 128 bytes RAM. The extra 128 bytes are inside
the 6803 CPU. Microcolor Basic uses that CPU RAM for some of its internal
data structures.

The CoCo needs a 256 byte buffer for cassette data files (PRINT#-1). The
MC-10 does not support data files so no space is allocated for a buffer.

The CoCo also provides a line input buffer large enough to accept program
lines of about 250 characters in length. The MC-10 only allows program
lines of about half that size, so its line input buffer is much smaller.

- Darren