keithe@teklabs.UUCP (04/02/84)
The Hesforth cartridge is a nice way to get started with Forth in the 64, but it has its drawbacks, not the least of which is its almost interminable disk access. The reason for the poor performance (even by c64 standards) is the format used for the storage of screens. Each screen - 1024 bytes of program source - is subdivided into 8 sections (128 bytes) and each section is stored on one disk sector. That means that (let's see... 254-128=) 126 bytes per sector is just plain wasted! Did you ever wonder why the manual sez something about a maximum of 90 screens - appx. 90 kbytes - per disk? Now you know why. This not only wastes disk storage, but it means that BLOCK must access the disk 8 times per screen. This is in contrast to the Precision Micro Forth (disk-based) that stores screens on 5 disk sectors. The disk access is cut by almost 40%, and the difference is noteable. The "saving grace" for the Hes is the 16 screens-worth of buffer space provided in high memory. But you won't want to work with applications of 17 or more screens.... keith ericson at teklabs