PAGE 1
                              AMS MAPPER
       ****************************************************************
        The AMS card has tons of documents as to its function and use.
       So to re-explain these docs would be pointless. Read the docs or
       find some, sorry but the RXB package is already huge.
 
     In PASS mode the mapper register setup is equivalent to:
 
     mapper address  mapper  page num            address range
     --------------  ------  --------            -------------
      HEX     Dec            HEX  Dec             memory area
      ---     ---            ---  ---             -----------
     >4004 = 16388 is MR02 = >02 = 02 points to >2000 - >2FFF range
     >4006 = 16390 is MR03 = >03 = 03 points to >3000 - >3FFF range
 
     >4014 = 16404 is MR10 = >0A = 10 points to >A000 - >AFFF range
     >4016 = 16406 is MR11 = >0B = 11 points to >B000 - >BFFF range
     >4018 = 16408 is MR12 = >0C = 12 points to >C000 - >CFFF range
     >401A = 16410 is MR13 = >0D = 13 points to >D000 - >DFFF range
     >401C = 16412 is MR14 = >0E = 14 points to >E000 - >EFFF range
     >401E = 16414 is MR15 = >0F = 15 points to >F000 - >FFFF range
 
     (MR=Mapper Register)
 
     In MAP mode the mapper register setup is equivalent to: EXAMPLE1
 
     mapper address  mapper  page num            address range
     --------------  ------  --------            -------------
      HEX     Dec            HEX  Dec             memory area
      ---     ---            ---  ---             -----------
     >4004 = 16388 is MR02 = >10 = 16 points to >2000 - >2FFF range
     >4006 = 16390 is MR03 = >11 = 17 points to >3000 - >3FFF range
 
     >4014 = 16404 is MR10 = >12 = 18 points to >A000 - >AFFF range
     >4016 = 16406 is MR11 = >13 = 19 points to >B000 - >BFFF range
     >4018 = 16408 is MR12 = >14 = 20 points to >C000 - >CFFF range
     >401A = 16410 is MR13 = >15 = 21 points to >D000 - >DFFF range
     >401C = 16412 is MR14 = >16 = 22 points to >E000 - >EFFF range
     >401E = 16414 is MR15 = >17 = 23 points to >F000 - >FFFF range
 
     (MR=Mapper Register)
 
     In MAP mode the mapper register setup is equivalent to: EXAMPLE2
 
     mapper address  mapper  page num            address range
     --------------  ------  --------            -------------
      HEX     Dec            HEX  Dec             memory area
      ---     ---            ---  ---             -----------
     >4004 = 16388 is MR02 = >19 = 31 points to >2000 - >2FFF range
     >4006 = 16390 is MR03 = >01 = 01 points to >3000 - >3FFF range
 
     >4014 = 16404 is MR10 = >09 = 09 points to >A000 - >AFFF range
     >4016 = 16406 is MR11 = >00 = 00 points to >B000 - >BFFF range
     >4018 = 16408 is MR12 = >07 = 07 points to >C000 - >CFFF range
     >401A = 16410 is MR13 = >18 = 30 points to >D000 - >DFFF range
     >401C = 16412 is MR14 = >05 = 05 points to >E000 - >EFFF range
     >401E = 16414 is MR15 = >04 = 04 points to >F000 - >FFFF range
 
     (MR=Mapper Register)

                                                                 PAGE 2
 
       As you can see you can switch pages around all you want.
 
       Each 4K page of the AMS memory can be engaged even into every
      4K section of the 32K at once. Thus giving multiple copies of
      the same 4K in every 4K chunk. Doing this has few useses but
      it demostrates the flexability of the AMS mapper.
 
       RXB limits the ability of the AMS slightly. All the memory of
      the AMS is used like this:
 
       1. 32K is used for pass mode. Think of it like normal a TI.
          24K for XB programs and variables, and lower 8K assembly
          support.
 
       2. 32K is used for future use. Stashed away for RXB future use.
 
       3. 4K pages of the rest of the AMS are for AMSBANK, a RXB
          routine that needs two (2) 4K pages of the AMS for the
          lower 8K of Assembly support.
 
       4. If a 256K AMS is used by RXB then 32K PASS mode, 32K future
          use, and the rest for AMSBANK. So 32+32=64 and 256-64=192
          then 192K of AMS 4K pages would be 192/4=48 or 48 pages of
          AMSBANK. Now the lower 8K needs two 4K pages becuase of
          course 8/4=2 so 48/2=24 and that means 24  8K assembly
          support routines from one XB program.
 
       5. BSAVE and BLOAD in RXB are subroutines to save or load the
          lower 8K as Program Image files. 33 sectors in length they
          are only used by BSAVE or BLOAD. The reasons for BSAVE is
          to save the lower 8K in one easy to load chunk. ALSAVE
          that creates hidden loaders has one huge disadvantage.
          ALSAVE can only save one assembly support program at a
          time. Also it can't load more than one support routine and
          XB program to run it. BLOAD can load many support routines
          into the AMS and control them from one XB program.
          BLOAD and BSAVE can do what ALSAVE can't. Also up to 1Meg
          can be loaded into the AMS from one XB program and the
          same program run the assembly support routines.
 
       6. ISR (Interupt Service Routine) hooks are used by many XB
          programs so CALL ISROFF and CALL ISRON are for RXB to
          control the problems created by them. Also compatability
          between software packages is ensured.

       DST  @STADDR,V@BUF(@PABPTR) for copy start
       ST   CZLOAD,V@COD(@PABPTR)   Select LOAD I/O code
       CALL CDSR              Call device service routine
       BR   OLDZ3             Not a program file, may be a  <<<<<<<<<<<<<<<<<<<<
*                              sequential file
* STADDR still points to the info bytes
       DST  V@2(@STADDR),@MNUM First test checksum
       DXOR V@4(@STADDR),@MNUM  which is a simple XOR
       DCEQ @MNUM,V*STADDR     Try PROTECTION option        <<<<<<<<<<<<<<<<<<<<
       BS   G8C15                                           <<<<<<<<<<<<<<<<<<<<
       DNEG @MNUM
       DCEQ @MNUM,V*STADDR    No-ERROR
       BR   OLDER