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**                                                                            **
**     R O S   8 . 1 4 B    Disassembled and commented by Th. Nouspikel, 1993 **
**                                                                            **
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This Ramdisk operating system is loaded in ram at >4000 to >57FF.
The area >5800 to >5FFF is used to display various pages, each corresponds to 8
disk sectors. Pages are selected by passing their number to cru bits 1 to 11.
Page 0 is reserved for continuation of the ROS.
 
Rambo mode is selected by setting cru bit 15 as 1: a bank made of 4 pages (8K)
appears at >6000 to >7FFF. It can be switched with cru bits 3 to 11 for a total
of 512 banks (i.e. 4 Mega). However opcode >B0 can only used 192 banks (1.5 M).
Also, the page at >5800 is changed: page 0  now contains rambo banks switching
routines and possibly user-defined dsr, interrupt and power-up routines.
 
 
 
Structure of the ROS:
=====================
 
The DSK. dsr routine starts at A455E, the DSKn dsrs at A45E4.
    ----                                  ----
They have a common part and then branch to the various opcode routines:
 
OPEN     A49B6
CLOSE    A4B8E
READ     A4BB0
WRITE    A4D6E
RESTORE  A4E6E
LOAD     A4E98
SAVE     A4EC0
DELETE   A4F3C
SCRATCH  A4F98
STATUS   A501C
ASSEMBLY A50CE
BASIC    A51CE
CATRIDGE A52BE
 
 
 
User dsr begins at A574E, by default it returns at A57F6
--------
 
 
Standard sbr main routine it at A4488, it calls the various sbrs:
------------
>10    A46F8  sector r/w
>11    A4728  format
>12    A473E  (un)protect
>13    A4764  rename
>14    A47BE  direct input
>15    A4842  direct output
 
N.B. sbr >16 (FILES) is not implemented: there are always 16 open files allowed
 
 
 
Ramdisk specific SBR, have there main routine at A444E, and are located at:
--------------------
AF     A5CD6  auto-start off
AO     A5CCE  auto-start on
DN     A5C5E  change drive number
WO     A5CC2  write-protection on
WF     A5CC8  write-protection off
LD     A573E  load program file (branches at A5CDC)
>B0    A57FC  rambo block operator
 
 
 
Interrupt routine is at A5752. Unless a vector is provided, it returns at A57F6.
-----------------
 
 
There are 2 power-up routines. The first is at A43EC:
            -----------------
- it clears the list of opened files,
- it loads a routine (located at A5DB0) at >A3A0 and branches to it,
- that routine looks for p-gram card, saves its cru address, and returns.
- it calls possible user-defined routines: by default it returns to A57F6
- it then returns if called from scratch-pad, or if power-up 2 is not there.
- else it tests shift key and returns if it's pressed,
- if not it copies a power-up scanning routine (located at A5E5C) at >A050
 
- this routine executes all remaining power-ups except for ramdisks 2nd power-up
  for those, it saves ramdisk cru address on a stack,
- when done, it saves part of the scratch-pad and executes the first sbr of each
  of the ramdisks saved on stack.
- if still in control by that time, it retrieves scratch-pad, displays copyright
  and return to the end of the console power-up scanning routine.
 
 
The second (optional) power-up:
- tests shift key and returns if it's pressed,
- else copies the same power-up scanning routine as above in high-memory and
  goes on just as above.