Im tracing through some code trying to figure out whats going on.

8983  218d8a    ld      hl,#8a8d <- See data below
8986  4e        ld      c,(hl)
8987  23        inc     hl
8988  7e        ld      a,(hl)
8989  23        inc     hl
898a  a7        and     a           <--? why and a with a? if a=0?
898b  280a      jr      z,#8997 
898d  47        ld      b,a
898e  0a        ld      a,(bc)      <-- bc? hmm, ok, so the data @8a8d contains addresses?
898f  57        ld      d,a
8990  3a0700    ld      a,(#0007)    <-- 7? ok, now im lost...
8993  82        add     a,d
8994  02        ld      (bc),a
8995  18ef      jr      #8986
8997  3ae0f3    ld      a,(#f3e0)
899a  e680      and     #80
899c  f602      or      #02
899e  3264f2    ld      (#f264),a
89a1  326bf2    ld      (#f26b),a
89a4  cd73f2    call    #f273
89a7  0680      ld      b,#80
89a9  2163f2    ld      hl,#f263
89ac  3a0700    ld      a,(#0007)
89af  3c        inc     a
89b0  4f        ld      c,a
89b1  7e        ld      a,(hl)
89b2  23        inc     hl
89b3  ed79      out     (c),a
89b5  ed41      out     (c),b
89b7  04        inc     b
89b8  cb58      bit     3,b
89ba  28f5      jr      z,#89b1

$8a8d looks like this

8a8d  b4 f2 77 f2 7b f2 7e f2  86 f2 8c f2 94 f2 97 f2
8a9d  a1 f2 a6 f2 ad f2 b1 f2  00 00

/frax

Hi,

1) the and a opcode is a quick way used to set the flags according to the content of a. In this case, it is used to set the Z flag, so that the next opcode jr z,#8997 can jump accordingly.

2) the ld a,(#0007) is used to load the VDP #0 port address (stored at $0007 in the ROM).

Apparently, what the first part of this routine does is :

- read a set of data through a library of addresses stored in #8A8D
- add to them the base address of the VDP #0 port
- store them back in their original location

Maybe in order to prepare quick VDP commands ?

Quote:

Maybe in order to prepare quick VDP commands ?

Hmm, kinky...

Nops, still don't quite geddit.

So let's summarize it:
- the first part (#8983-#8995) writes the correct VDP port number to an amount of addresses around #f2xx, which are specified in the zero-treminated table
- the second part (#8997-#89a4) I don't understand (don't know the addresses and calls)
- the third and last part (#89a7-#89ba) seems to write init values (stored at #f263) to the VDP registers 0-7 (which are the basic MSX1 video registers)