blk: Add LOAD+ and LOADR+

And use them in all places they make sense.

blk/003

@@ -13,4 +13,4 @@ Contents
  4 Number literals              6 Compilation vs meta-comp.
  8 Interpreter I/O             11 Signed-ness
 14 Addressed devices           17 DOES>
-
+18 Disk blocks

blk/018

@@ -0,0 +1,16 @@
+Disk blocks
+
+Disk blocks are Collapse OS' main access to permanent storage.
+The system is exceedingly simple: blocks are contiguous 
+chunks of 1024 bytes each living on some permanent media such
+as floppy disks or SD cards. They are mostly used for text,
+either informational or source code, which is organized into
+16 lines of 64 characters each.
+
+Blocks are referred to by number, 0-indexed. They are read
+through BLK@ and written through BLK!. When a block is read,
+its 1024 bytes content is copied to an in-memory buffer
+starting at BLK( and ending at BLK). Those read/write
+operations are often implicit. For example, LIST calls BLK@.
+
+                                                        (cont.)

blk/019

@@ -0,0 +1,16 @@
+When a word modifies the buffer, it sets the buffer as dirty
+by calling BLK!!. BLK@ checks, before it reads its buffer,
+whether the current buffer is dirty and implicitly calls BLK!
+when it is.
+
+The index of the block currently in memory is kept in BLK>.
+
+Many blocks contain code. That code can be interpreted through
+LOAD. Programs stored in blocks frequently have "loader blocks"
+that take care of loading all blocks relevant to the program.
+
+Blocks spanning multipls disks are tricky. If your media isn't
+large enough to hold all Collapse OS blocks in one unit, you'll
+have to make it span multiple disks. Block reference in
+informational texts aren't a problem: When you swap your disk,
+you mentally adjust the block number you fetch.         (cont.)

blk/020

@@ -0,0 +1,8 @@
+However, absolute LOAD operations in Collapse OS aren't aware
+of disk spanning and will not work properly in your spanned
+system.
+
+Although the usage of absolute LOAD calls are minimally used
+(relative LOADs are preferred), they are sometimes unavoidable.
+When you span Collapse OS over multiple disks, don't forget to
+adjust those absolute LOADs.

blk/064

@@ -1,15 +1,17 @@
 Disk
 
-BLK>  -- a      Address of the current block variable.
+BLK>   -- a      Address of the current block variable.
-BLK(  -- a      Beginning addr of blk buf.
+BLK(   -- a      Beginning addr of blk buf.
-BLK)  -- a      Ending addr of blk buf.
+BLK)   -- a      Ending addr of blk buf.
-COPY  s d --    Copy contents of s block to d block.
+COPY   s d --    Copy contents of s block to d block.
-FLUSH --        Write current block to disk if dirty.
+FLUSH  --        Write current block to disk if dirty.
-LIST  n --      Prints the contents of the block n on screen
+LIST   n --      Prints the contents of the block n on screen
-                in the form of 16 lines of 64 columns.
+                 in the form of 16 lines of 64 columns.
-LOAD  n --      Interprets Forth code from block n
+LOAD   n --      Interprets Forth code from block n
-LOADR n1 n2 --  Load block range between n1 and n2, inclusive.
+LOAD+  n --      Relative load. Loads active block + n.
-WIPE  --        Empties current block
+LOADR  n1 n2 --  Load block range between n1 and n2, inclusive.
+LOADR+ n1 n2 --  Relative ranged load.
+WIPE   --        Empties current block
 
 
 

blk/102

@@ -1,9 +1,8 @@
-152 LOAD ( extras )
+50 LOAD+ ( B152, extras )
-103 107 LOADR
+1 5 LOADR+
 
 : BROWSE
-    100 _LIST
+    L BEGIN
-    BEGIN
         KEY CASE
             'Q' OF EXIT ENDOF
             'B' OF B ENDOF

blk/122

@@ -1 +1 @@
-123 131 LOADR
+1 9 LOADR+

blk/142

@@ -1 +1 @@
-143 144 LOADR
+1 2 LOADR+

blk/152

@@ -1,3 +1,3 @@
 '? CASE NOT [IF]
-    153 157 LOADR
+    1 5 LOADR+
 [THEN] DROP ( from '? )

blk/212

@@ -1,2 +1,2 @@
-213 LOAD Z80A$
+1 LOAD+ Z80A$
-215 249 LOADR
+3 37 LOADR+

blk/262

@@ -1 +1 @@
-263 LOAD 265 LOAD 268 LOAD 269 LOAD
+1 LOAD+ 3 LOAD+ 6 LOAD+ 7 LOAD+

blk/282

@@ -1 +1 @@
-283 333 LOADR
+1 51 LOADR+

blk/352

@@ -11,5 +11,5 @@ ACIA_MEM
   +4 ACIA(
   +6 ACIA) )
 
-353 355 LOADR
+1 3 LOADR+
 

blk/357

@@ -1 +1 @@
-358 360 LOADR
+1 3 LOADR+

blk/374

@@ -13,4 +13,4 @@
     DUP 20 = UNTIL
     DROP 0xff
 ;
-375 386 LOADR
+1 12 LOADR+

blk/393

@@ -12,4 +12,4 @@
     0 0x08 RAM+ !  ( 08 == C<* override )
     LIT< INTERPRET (find) DROP EXECUTE
 ;
-394 413 LOADR
+1 20 LOADR+

blk/459

@@ -1,2 +1,4 @@
+: LOAD+ BLK> @ + LOAD ;
 ( b1 b2 -- )
 : LOADR 1+ SWAP DO I DUP . NL LOAD LOOP ;
+: LOADR+ BLK> @ + SWAP BLK> @ + SWAP LOADR ;

blk/492

@@ -1 +1 @@
-493 497 LOADR
+1 5 LOADR+

blk/498

@@ -1 +1 @@
-499 500 LOADR
+1 2 LOADR+