Author: Claire Wilson
System: Amstrad CPC464
Language: Z80 assembly
Source Length: 31 lines (851 bytes)
Executable length: 48 bytes (37 executable, 11 data)
Description:
There's an 11 byte array (xpos) denoting the number of stars per row
Centre of an Amstrad CPC464 in mode 1 is column 20 so we get an x location
of 20-x/2 (or, as executed lines 9~12 20, value at current ix which is a pointer
into xpos shifted right 1; 20 is subtracted from this). For authenticity, I use
the Firmware call to emulate the standard text mode to locate the text cursor 
then run the loop to print the number of stars indicated again calling the firmware's
print character routine. Increment row count, increment xpos pointer in ix, if we're
not on the 15th row (beyond buffer), rinse and repeat.