Version analysis of TRANTABLE / TRTB% - Elite on the BBC Micro and NES

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

6502 Second Processor and Master

Code variations between these versions are shown below.

Code variation 1 of 3A variation in the comments only

Tap on a block to expand it, and tap it again to revert.

Master
6502SP
       Name: TRTB%
       Name: TRANTABLE

       Type: Variable
   Category: Keyboard
    Summary: Translation table from internal key number to ASCII

Code variation 2 of 3A variation in the comments only

Tap on a block to expand it, and tap it again to revert.

Master
6502SP
 This is a copy of the keyboard translation table from the BBC Master's MOS
 3.20 ROM. The value at offset n is the upper-case ASCII value of the key with
 internal key number n, so for example the value at offset &10 is &51, which is
 81, or ASCII "Q", so internal key number &10 is the key number of the "Q"
 key.
 This is a copy of the keyboard translation table from the BBC Micro's MOS 1.20
 ROM. The value at offset n is the lower-case ASCII value of the key with
 internal key number n, so for example the value at offset &10 is &71, which is
 113, or ASCII "q", so internal key number &10 is the key number of the "Q"
 key.


 Valid internal key numbers are Binary Coded Decimal (BCD) numbers in the range
 &10 top &79, so they're in the ranges &10 to &19, then &20 to &29, then &30 to
 &39, and so on. This means that the other locations - i.e. &1A to &1F, &2A to
 &2F and so on - aren't used by the lookup table, but the MOS doesn't let this
 space go to waste; instead, those gaps contain MOS code, which is replicated
 below as the table contains a copy of this entire block of the MOS, not just
 the table entries.

 This table allows code running on the parasite to convert internal key numbers
 into ASCII codes in an efficient way. Without this table we would have to do a
 lookup from the table in the I/O processor's MOS ROM, which we would have to
 access from across the Tube, and this would be a lot slower than doing a
 simple table lookup in the parasite's user RAM.

Code variation 3 of 3Specific to an individual platform

Tap on a block to expand it, and tap it again to revert.

Master
6502SP
.TRTB%

 EQUB &00, &40, &FE     \ MOS code
 EQUB &A0, &5F, &8C
 EQUB &43, &FE, &8E
 EQUB &4F, &FE, &EA
 EQUB &AE, &4F, &FE
 EQUB &60

                        \ Internal key numbers &10 to &19:
                        \
 EQUB &51, &33          \ Q             3
 EQUB &34, &35          \ 4             5
 EQUB &84, &38          \ f4            8
 EQUB &87, &2D          \ f7            -
 EQUB &5E, &8C          \ ^             Left arrow

 EQUB &36, &37, &BC     \ MOS code
 EQUB &00, &FC, &60

                        \ Internal key numbers &20 to &29:
                        \
 EQUB &80, &57          \ f0            W
 EQUB &45, &54          \ E             T
 EQUB &37, &49          \ 7             I
 EQUB &39, &30          \ 9             0
 EQUB &5F, &8E          \ _             Down arrow

 EQUB &38, &39, &BC     \ MOS code
 EQUB &00, &FD, &60

                        \ Internal key numbers &30 to &39:
                        \
 EQUB &31, &32          \ 1             2
 EQUB &44, &52          \ D             R
 EQUB &36, &55          \ 6             U
 EQUB &4F, &50          \ O             P
 EQUB &5B, &8F          \ [             Up arrow

 EQUB &81, &82, &0D     \ MOS code
 EQUB &4C, &20, &02

                        \ Internal key numbers &40 to &49:
                        \
 EQUB &01, &41          \ CAPS LOCK     A
 EQUB &58, &46          \ X             F
 EQUB &59, &4A          \ Y             J
 EQUB &4B, &40          \ K             @
 EQUB &3A, &0D          \ :             RETURN

 EQUB &83, &7F, &AE     \ MOS code
 EQUB &4C, &FE, &FD

                        \ Internal key numbers &50 to &59:
                        \
 EQUB &02, &53          \ SHIFT LOCK    S
 EQUB &43, &47          \ C             G
 EQUB &48, &4E          \ H             N
 EQUB &4C, &3B          \ L             ;
 EQUB &5D, &7F          \ ]             DELETE

 EQUB &85, &84, &86     \ MOS code
 EQUB &4C, &FA, &00

                        \ Internal key numbers &60 to &69:
                        \
 EQUB &00, &5A          \ TAB           Z
 EQUB &20, &56          \ Space         V
 EQUB &42, &4D          \ B             M
 EQUB &2C, &2E          \ ,             .
 EQUB &2F, &8B          \ /             COPY

 EQUB &30, &31, &33     \ MOS code
 EQUB &00, &00, &00

                        \ Internal key numbers &70 to &79:
                        \
 EQUB &1B, &81          \ ESCAPE        f1
 EQUB &82, &83          \ f2            f3
 EQUB &85, &86          \ f5            f6
 EQUB &88, &89          \ f8            f9
 EQUB &5C, &8D          \ \             Right arrow

 EQUB &34, &35, &32     \ MOS code
 EQUB &2C, &4E, &E3
.TRANTABLE

 EQUB &03, &8C, &40     \ MOS code
 EQUB &FE, &A0, &7F
 EQUB &8C, &43, &FE
 EQUB &8E, &4F, &FE
 EQUB &AE, &4F, &FE
 EQUB &60

                        \ Internal key numbers &10 to &19:
                        \
 EQUB &71, &33          \ Q             3
 EQUB &34, &35          \ 4             5
 EQUB &84, &38          \ f4            8
 EQUB &87, &2D          \ f7            -
 EQUB &5E, &8C          \ ^             Left arrow

 EQUB &84, &EC, &86     \ MOS code
 EQUB &ED, &60, &00

                        \ Internal key numbers &20 to &29:
                        \
 EQUB &80, &77          \ f0            W
 EQUB &65, &74          \ E             T
 EQUB &37, &69          \ 7             I
 EQUB &39, &30          \ 9             0
 EQUB &5F, &8E          \ _             Down arrow

 EQUB &6C, &FE, &FD     \ MOS code
 EQUB &6C, &FA, &00

                        \ Internal key numbers &30 to &39:
                        \
 EQUB &31, &32          \ 1             2
 EQUB &64, &72          \ D             R
 EQUB &36, &75          \ 6             U
 EQUB &6F, &70          \ O             P
 EQUB &5B, &8F          \ [             Up arrow

 EQUB &2C, &B7, &D9     \ MOS code
 EQUB &6C, &28, &02

                        \ Internal key numbers &40 to &49:
                        \
 EQUB &01, &61          \ CAPS LOCK     A
 EQUB &78, &66          \ X             F
 EQUB &79, &6A          \ Y             J
 EQUB &6B, &40          \ K             @
 EQUB &3A, &0D          \ :             RETURN

 EQUB &00, &FF, &01     \ MOS code
 EQUB &02, &09, &0A

                        \ Internal key numbers &50 to &59:
                        \
 EQUB &02, &73          \ SHIFT LOCK    S
 EQUB &63, &67          \ C             G
 EQUB &68, &6E          \ H             N
 EQUB &6C, &3B          \ L             ;
 EQUB &5D, &7F          \ ]             DELETE

 EQUB &AC, &44, &02     \ MOS code
 EQUB &A2, &00, &60

                        \ Internal key numbers &60 to &69:
                        \
 EQUB &00, &7A          \ TAB           Z
 EQUB &20, &76          \ Space         V
 EQUB &62, &6D          \ B             M
 EQUB &2C, &2E          \ ,             .
 EQUB &2F, &8B          \ /             COPY

 EQUB &AE, &41, &02     \ MOS code
 EQUB &4C, &AD, &E1

                        \ Internal key numbers &70 to &79:
                        \
 EQUB &1B, &81          \ ESCAPE        f1
 EQUB &82, &83          \ f2            f3
 EQUB &85, &86          \ f5            f6
 EQUB &88, &89          \ f8            f9
 EQUB &5C, &8D          \ \             Right arrow

 EQUB &6C, &20, &02     \ MOS code
 EQUB &D0, &EB, &A2
 EQUB &08