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Elite on the BBC Micro

Version analysis of KYTB

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

Code variations between these versions are shown below.

Name: KYTB Type: Variable Category: Keyboard Summary: Lookup table for in-flight keyboard controls Deep dive: The key logger

Code variation 1 of 6A variation in the comments only

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Cassette, Flight, 6502SP

Master

Electron

Keyboard table for in-flight controls. This table contains the internal key codes for the flight keys (see p.142 of the Advanced User Guide for a list of internal key numbers).
Keyboard table for in-flight controls. This table contains the internal key codes for the flight keys, EOR'd with &FF to invert each bit.
Keyboard table for in-flight controls. This table contains the internal key codes for the flight keys (see p.40 of the Electron Advanced User Guide for a list of internal key numbers).
The pitch, roll, speed and laser keys (i.e. the seven primary flight control keys) have bit 7 set, so they have 128 added to their internal values. This doesn't appear to be used anywhere.

Code variation 2 of 6A variation in the comments only

This variation is blank in the Cassette and Master versions.

Flight, 6502SP, Electron

Note that KYTB actually points to the byte before the start of the table, so the offset of the first key value is 1 (i.e. KYTB+1), not 0. Other entry points: KYTB Contains an RTS

Code variation 3 of 6A variation in the labels only

Tap on a version to expand it, and tap it again to show to all variations.

Cassette

Flight, 6502SP, Master, Electron

KYTB = P% - 1 \ Point KYTB to the byte before the start of the table
.KYTB

Code variation 4 of 6A variation in the labels only

This variation is blank in the Cassette and Master versions.

Flight, 6502SP, Electron

RTS \ Return from the subroutine (used as an entry point and \ a fall-through from above)

Code variation 5 of 6Related to the Master version

The Master has a very different set of internal key numbers to the BBC Micro and Electron, so the keyboard lookup table for the Master is also very different; the Electron and BBC Micro are much more similar, but the Electron has no TAB key, so "-" launches an energy bomb instead.

Tap on a version to expand it, and tap it again to show to all variations.

Cassette, Flight, 6502SP

Master

Electron

\ These are the primary flight controls (pitch, roll, \ speed and lasers): EQUB &68 + 128 \ ? KYTB+1 Slow down EQUB &62 + 128 \ Space KYTB+2 Speed up EQUB &66 + 128 \ < KYTB+3 Roll left EQUB &67 + 128 \ > KYTB+4 Roll right EQUB &42 + 128 \ X KYTB+5 Pitch up EQUB &51 + 128 \ S KYTB+6 Pitch down EQUB &41 + 128 \ A KYTB+7 Fire lasers \ These are the secondary flight controls: EQUB &60 \ TAB KYTB+8 Energy bomb EQUB &70 \ ESCAPE KYTB+9 Launch escape pod EQUB &23 \ T KYTB+10 Arm missile EQUB &35 \ U KYTB+11 Unarm missile EQUB &65 \ M KYTB+12 Fire missile EQUB &22 \ E KYTB+13 E.C.M. EQUB &45 \ J KYTB+14 In-system jump EQUB &52 \ C KYTB+15 Docking computer
EQUB &DD EOR &FF \ E KYTB+0 KY13 E.C.M. EQUB &DC EOR &FF \ T KYTB+1 KY10 Arm missile EQUB &CA EOR &FF \ U KYTB+2 KY11 Unarm missile EQUB &C8 EOR &FF \ P KYTB+3 KY16 Cancel docking computer EQUB &BE EOR &FF \ A KYTB+4 KY7 Fire lasers EQUB &BD EOR &FF \ X KYTB+5 KY5 Pitch up EQUB &BA EOR &FF \ J KYTB+6 KY14 In-system jump EQUB &AE EOR &FF \ S KYTB+7 KY6 Pitch down EQUB &AD EOR &FF \ C KYTB+8 KY15 Docking computer EQUB &9F EOR &FF \ TAB KYTB+9 KY8 Energy bomb EQUB &9D EOR &FF \ Space KYTB+10 KY2 Speed up EQUB &9A EOR &FF \ M KYTB+11 KY12 Fire missile EQUB &99 EOR &FF \ < KYTB+12 KY3 Roll left EQUB &98 EOR &FF \ > KYTB+13 KY4 Roll right EQUB &97 EOR &FF \ ? KYTB+14 KY1 Slow down EQUB &8F EOR &FF \ ESCAPE KYTB+15 KY9 Launch escape pod EQUB &F0 \ This value just has to be higher than &80 to act as a \ terminator for the KYTB matching process in DKS1
\ These are the primary flight controls (pitch, roll, \ speed and lasers): EQUB &68 + 128 \ ? KYTB+1 Slow down EQUB &62 + 128 \ Space KYTB+2 Speed up EQUB &66 + 128 \ < KYTB+3 Roll left EQUB &67 + 128 \ > KYTB+4 Roll right EQUB &42 + 128 \ X KYTB+5 Pitch up EQUB &51 + 128 \ S KYTB+6 Pitch down EQUB &41 + 128 \ A KYTB+7 Fire lasers \ These are the secondary flight controls: EQUB &17 \ - KYTB+8 Energy bomb EQUB &70 \ ESCAPE KYTB+9 Launch escape pod EQUB &23 \ T KYTB+10 Arm missile EQUB &35 \ U KYTB+11 Unarm missile EQUB &65 \ M KYTB+12 Fire missile EQUB &22 \ E KYTB+13 E.C.M. EQUB &45 \ J KYTB+14 In-system jump EQUB &52 \ C KYTB+15 Docking computer

Code variation 6 of 6Related to an enhanced feature

The lookup table for in-flight keyboard controls contains an extra entry in the enhanced versions, for "P" (cancel docking computer).

This variation is blank in the Cassette, Master and Electron versions.

Flight, 6502SP

EQUB &37 \ P KYTB+16 Cancel docking computer
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