Architecture Diagram (Pikchr)

    lineht *= 0.4
    $margin = lineht*2.5
    scale = 0.75
    fontscale = 1.1
    charht *= 1.15
    down
In: box "Interface" wid 150% ht 75% fill white
    arrow
CP: box same "SQL Command" "Processor"
    arrow
VM: box same "Virtual Machine"
    arrow down 1.25*$margin
BT: box same "B-Tree"
    arrow
    box same "Pager"
    arrow
OS: box same "OS Interface"
    box same with .w at 1.25*$margin east of 1st box.e "Tokenizer"
    arrow
    box same "Parser"
    arrow
CG: box same ht 200% "Code" "Generator"
UT: box same as 1st box at (Tokenizer,Pager) "Utilities"
    move lineht
TC: box same "Test Code"
    arrow from CP to 1/4<Tokenizer.sw,Tokenizer.nw> chop
    arrow from 1/3<CG.nw,CG.sw> to CP chop

    box ht (In.n.y-VM.s.y)+$margin wid In.wid+$margin        at CP fill 0xd8ecd0 behind In
    line invis from 0.25*$margin east of last.sw up last.ht         "Core" italic aligned

    box ht (BT.n.y-OS.s.y)+$margin wid In.wid+$margin        at Pager fill 0xd0ece8 behind In
    line invis from 0.25*$margin east of last.sw up last.ht        "Backend" italic aligned

    box ht (Tokenizer.n.y-CG.s.y)+$margin wid In.wid+$margin        at 1/2<Tokenizer.n,CG.s> fill 0xe8d8d0 behind In
    line invis from 0.25*$margin west of last.se up last.ht        "SQL Compiler" italic aligned

    box ht (UT.n.y-TC.s.y)+$margin wid In.wid+$margin        at 1/2<UT,TC> fill 0xe0ecc8 behind In
    line invis from 0.25*$margin west of last.se up last.ht       "Accessories" italic aligned