Version analysis of QQ23 - Elite on the 6502

This code appears in the following versions (click to see it in the source code):

Cassette, Disc (flight), Disc (docked), 6502 Second Processor, Master and Electron

Code variations between these versions are shown below.

       Name: QQ23
       Type: Variable
   Category: Market
    Summary: Market prices table
  Deep dive: Market item prices and availability


 Each item has four bytes of data, like this:

   Byte #0 = Base price
   Byte #1 = Economic factor in bits 0-4, with the sign in bit 7
             Unit in bits 5-6
   Byte #2 = Base quantity
   Byte #3 = Mask to control price fluctuations

 To make it easier for humans to follow, I've defined a macro called ITEM
 that takes the following arguments and builds the four bytes for us:

   ITEM base price, economic factor, units, base quantity, mask

 So for food, we have the following, for example:

   * Base price = 19
   * Economic factor = -2
   * Unit = tonnes
   * Base quantity = 6
   * Mask = %00000001


.QQ23

 ITEM 19,  -2, 't',   6, %00000001  \  0 = Food
 ITEM 20,  -1, 't',  10, %00000011  \  1 = Textiles
 ITEM 65,  -3, 't',   2, %00000111  \  2 = Radioactives
 ITEM 40,  -5, 't', 226, %00011111  \  3 = Slaves
 ITEM 83,  -5, 't', 251, %00001111  \  4 = Liquor/Wines
 ITEM 196,  8, 't',  54, %00000011  \  5 = Luxuries
 ITEM 235, 29, 't',   8, %01111000  \  6 = Narcotics
 ITEM 154, 14, 't',  56, %00000011  \  7 = Computers
 ITEM 117,  6, 't',  40, %00000111  \  8 = Machinery
 ITEM 78,   1, 't',  17, %00011111  \  9 = Alloys
 ITEM 124, 13, 't',  29, %00000111  \ 10 = Firearms
 ITEM 176, -9, 't', 220, %00111111  \ 11 = Furs
 ITEM 32,  -1, 't',  53, %00000011  \ 12 = Minerals
 ITEM 97,  -1, 'k',  66, %00000111  \ 13 = Gold

Code variation 1 of 1A variation in the comments only

This variation is blank in the Cassette, Disc (flight), Disc (docked) and Electron versions.

6502SP, Master
\EQUD &360A118          \ This data is commented out in the original source
                        \
                        \ It would have inserted an item as follows:
                        \
                        \   ITEM 24, -1, 'k',  96, %00000011
                        \
                        \ So that's an item with a base price of 24 credits that
                        \ is slightly cheaper than average in agricultural
                        \ economies but closer to average in rich industrial
                        \ ones, with a base quantity of 96kg and a reasonably
                        \ stable price
                        \
                        \ I wonder what this mysterious item was going to be?

 ITEM 171, -2, 'k',  55, %00011111  \ 14 = Platinum
 ITEM 45,  -1, 'g', 250, %00001111  \ 15 = Gem-Stones
 ITEM 53,  15, 't', 192, %00000111  \ 16 = Alien items