Commodore RF512C - Principles

4
PRINCIPLES
One of the most i mpo rtant advantages of th is d ri ve is that in f or-
mat ion can be sto r ed and re trieved by a name under which
it is filed.
The programs that automatica l ly keep track of f il e s, save and
retrieve information, and do a multitude of other housekeeping
tasks are ca l ed the Disk Ope rating System , usually shortened
to " DOS ".
In th is DOS , t he path which link between the computer and
pe ripheral is called channel. Each pe ripheral must be ass i gned
for a specific de vi ce number (usually 8 for disk dr i ve) a nd a
logica l file is spec if ied for data transf er.
The re have 15 available channel s, and channel 15 is reserved
as the command ch anne l. The logi cal file number can be
assigned fr am 1 to. 127. The di sk drive dev ice number can be
speci fi ed from 1 to 32 by saftware (but only 8,9, 10 and 11 can
be set by ha r dware switch ). T he dr ive number is always 0 (zero)
in s in gle di sk d ri ve sys tem.
So, the typical form for se nd i ng cammand to the d ri ve is lis t ed
be low:
Example: OPEN 1,8,15, ' '# '' : REM open logical fi le 1 for device
8 thraugh channel 15 and the
message is " II ".
In GCR sys tem, a di sk is for matt ed 35 trackS/s ide a nd the op timal
sectoring is shawn as belaw:
Track
Sectar As s ignment
1- 17 0-20
18 -24 0- 18
25-30 0- 17
31-35 0- 16
In RF512C, the tracks an side one are ass ign ed from 36 t o. 70
wi th sector no. as t rac k 1 to 35, respec ti vely.