Microsoft Extended BASIC, as used by the Dragon, uses a 40 bit (5 byte) float format(*1):
Field Size (Bits)
Exponent Sign 1
Mantissa Sign 1
Numbers are always normalized with the top mantissa bit removed.
As an oddity, they are stored in a 6 byte ...
As far as I can see, any Microsoft BASIC at that time should have used Microsoft Binary Format for floating-point numbers. Since you found out that numbers are occupying five bytes, that should mean that your implementation is using the 40-bit format.
This format is similar enough to IEEE-754 binary formats in that it has a sign bit, a base-2, biased ...
You may want to look at the PARANOIA floating point test suite, which tests for quite a few characteristics of the floating point format and implementation (range, bits of precision, rounding, guard bits, etc.).
It is said that it was originally written in BASIC, but I could not find the BASIC version (EDIT: hat tip to @scruss, here it is). The C variant, as ...
I've made a couple of discoveries after a night's sleep.
The CoCo still reads the leader length from a RAM address, but its address is two bytes higher in memory than in the Dragon 32:
0199 ** THESE BYTES ARE MOVED DOWN FROM ROM
0200 *** INIT DESCRIPTION
0201 * VALUE
0202 008F CMPMID RMB 1 18 *PV 1200/2400 HERTZ PARTITION
0203 0090 CMP0 RMB 1 24 *PV UPPER ...
Since the coco cassette interface used 1200 baud psk audio encoding in it, the tape format of the coco was 4X faster loading files from the tape and the tape files were 1/4th the size of similar files on atari and commodore systems, which used 300 baud afsk encoding.
it became common to stack multiple files on a single tape. many magazines sold software ...