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V9990 evaluation board. The first impression.
Henrik Gilvad, 00-00-00

(Overgenomen van Quasar 26)

V9990 evaluation board. The first impression. 
Written by Henrik Gilvad. 
It  have been a while since I last wrote for the Quasar and the
 reason is  not difficult  to explain.  I got a V9990
evaluation  board  from MSX  Handler Gemeinshaft with an
interface for MSX.  From now on there will be 2 kinds of MSX
people, those who hate  the V9990  and those who love it. After
this article you should  have no doubts about what group I
belong to. 
The first rumours: 
I  first  heard  about  the  V9990  several years  ago, it  was
 mentioned together  with a  new MSX computer which had a 16
bit  28 MHz Risc CPU. The new videochip had up to 2048 dots in
the X  direction  and 2048  in the  Y direction,  with 32k
colours the  quality  would     beat  all  existing  hobby 
systems.  Quite  a  mouthfull  of words  so we  didnt really
believed it then, only  hoped. 
The facts  of both  the 28  MHz and  the 2048/1024 dots was not
 precisely  correct but  misunderstandings from people who
could  not read  and understand the technical information. The
machine  was  naturally    the  Turbo R,  all though  not as 
fast as  the  rumour.  The V9990  DOES have up to 2048 in the X
direction and  up to 2048 in the Y dir. but that is in the vram
and NOT on the  screen. The  V9990 is  a very complex chip but
it is incredible  simple      to program  and therefore the
'thru-put' is much faster  than on  the know  MSX VDP's. 
Furthermore the  V9990 is ALWAYS  ready  for the Turbo R,
therefore it is possible to transfer up  to 520kbyte  or so 
from the  Turbo R  internal RAM to the VRAM  with  OUT's. This 
is nice  but the REAL power is internally of  the V9990,  the
hardwarecommands  and other  features are  much  more  valuable
than  even 2 or 4 higher CPU to VRAM access. (My  personal
I will      not write  about the  things that  you can  read in
the  Application  Manual, get  that one from Arjan. I will
bring you  here the test results and other things that I found
To see the strength of the V9990 I did some first tests. 
The  following tests  have been  made in  a screen 7 compatible
 mode. Optimized machinecode. 
LMMV  LINE BOXFILL      Fill's about 3.183 Mbyte /sek in B1
mode CMMK  KANJI to (X,Y)    Writes about 3.076 Mbyte /sek
--!!-- LMMM  COPY (X,Y)  Transfers    2.248 Mbyte /sek 
(Faster if sprites/cursor is disabled) 
in P2 mode with the same commands: 
LMMV  1.267 Mbyte 
CMMK  1.047 Mbyte 
LMMM    756 Kbyte 
(Also faster with disabled sprites.) 
I have      also tried to see how many Lines and Copy's the
Turbo R  can give in M-Code with different size. (All in B1
LINE -STEP(3,3)   26087 lines in 1 sek. 
LINE -STEP(16,16)       20689 lines in 1 sek. 
LINE -STEP(31,31)       15384 lines in 1 sek. 
LINE (0,0)-(255,211)     4054 lines in 1 sek. 
and COPY: 
COPY step(15,15)   8696 times in 1 sek. 
COPY step(31,31)   3141 times in 1 sek. 
The  B1 mode is with only 2 sprites (called Cursors) with 32x32
 pixels and multicolour. 
The P2 and P1 modes have up to 125 sprites with 16x16 pixels in
 multicolour. 16 per line. 
Compared to  the V9958  then the  V9990 is  MUCH faster  in all
 concepts.  The V9958  have 2  kinds of    COPY. One  with
logical  operations (in    DOT units)  and one  without
log.ops.  (In BYTE  units) The Byte copy is never faster than
350 K/sek and the Dot  Copy  is only  pumping out  about
100kbyte/sek.  The V9990 only  have 1      COPY and that is
always with Logical operations between  the  Source and  the
Destination. If the V9990 COPY is compared  with  the  V9958
Dot  COPY then  it is    23 times  faster !  But  compared with
the V9958  Byte COPY it is 'only' 9 times faster  in this
command type. 
So  was the V9958 so bad ?? The answer is no, the VRAM was bad.
 The V9990 can only use what is known as REAL video-ram, that
is  also called  DUAL PORT RAM. The problem has been that 1 ram
had  to deliver data to both the picture (Which can not wait
for its  information.)  and the  'blitter', that is not
possible in very  high resolutions.  Actually the  V9958 can 
only show  SCREEN 5  with  one  VRAM  bank, it  have to  have 2
banks to  go up  to  resolutions as the Screen 7 and 8. On the
IBM-PC VGA cards they  have NO 'blitter' and NO sprites. With
these 2 things VGA would  never existed, with normal RAM. Most
VGA cards have to split up  the  VRAM in  4 or  8 banks to get
enough 'access time' just to  show the screen resolution *
number of colours. 
With the  new DUAL  PORT ram  then V9990  have 1  port for  the
 Picture  and 1 port for 'blitter', sprites and CPU access.
This  gives  the  possibility of  the high  speeds and  higher
screen  resolutions in both dots and colours. 
So, does V9990 have ANY MSX future ? 
The first  3 days  or so  I did  not get much sleep, I was busy
 converting  XBASIC and Turbo R BASIC from V9958 to V9990.
After  about 1  week I  had most routines rewritten and they
were both  faster and smaller ! I didnt belived it myself but
this chip is  so  damn brilliant. Take a basic command like the
"COPY file to  (X,Y)" it is hopeless in screen 8 and even worse
in screen 6. 
Each dot  have to  be read  from the  diskfile, masked      out
and  written  to the  VDP, but before each dot the SUBROM first
have  to set      and examine some status registers. ALL the
work is done  by the CPU and not by the videoprocessor as it
should be. There  are  4      different  COPY routines  in the 
SUBROM, one  for each  screen      mode. The  V9990 have  a
hardware  command that is much  simpler to use. Just read the
data from the disk and write them  directly to  a VDP  port, it
does the rest. The new routine is  really      much faster. 
The V9990 will distribute the data to the  correct dots,  no
masking  to be  done ! The V9990 command even  IGNORES  the
last  bits in  the right side of the rectangle you  are copying
to, for  those who dont know it then this is a MSX 
speciallity. The V9990 fits the MSX to a fault not only in this
 point but it also contains other commands fit for MSX BASIC
and  BIOS. 
Other  basic commands  that was getting much faster and smaller
Commands like LINE, PSET, POINT was not different in size. 
The V9990  can simulate all MSX 2 and 2+ screen modes in matter
 of  the DOTS.  The incompatibility starts with SPRITES and
with  VDP registers. 
The old  sprite system  was really  bad, take a look on the PUT
 SPRITE      function in  the SUBROM  and you will understand
what I  mean. To  make 1  PUT SPRITE command takes about 200
VPEEKS and  VPOKES      and lots  of calculations. Sprites on
the V9990 is very  simple and more powerfull at the same time. 
Sprites  are  now defined  just as  normal bitmapped  graphics,
 actually you  can use  normal graphic as spritedata. This
makes  sprites much more usefull. 
Sprites can have 1 of 4 palettes (1 palette have 16 colours) so
 with sprites there can be up to 64 colours on the screen in
the  'GAME MODES'. 
Sprites  can move BEHIND the picture or between the 2 planes in
 P1 mode, so the 2 planes can be huge sprites themselves. 
Sprites on  the V9990  are NOT      vram compatible with the
V9958,  that would be imposible. 
VDP  registers are not compatible either, this was not possible
 as there  have been  so many  improvements. If  programmers
are  using  BASIC, XBASIC,  C or  Assembler with BIOS based
routines  then there  should be no problems. But Assembler
programs which  writes      to VDP      registers and  VRAM and
not using the BIOS will  not work correctly. 
The  MSX  standard does  not permit  anyone to  access the  vdp
 registers directly. 
The only legal and fast way to access the VRAM, bitmap graphics
 area, is  by setting  up the  VRAM ADR. with a BIOS routine
and  then writing vram data directly to the I/O port which is
stored  in  ROM adr.  6-7. It is not allowed to use the VDP
regs to set  up  the  adr.  If  this  is  done correctly  then
the  V9990 is  compatible. 
Now 2 examples. Ex1 is the wrong one, Ex2 is the right one. 
Ex1: Write 255 bytes from RAM to VRAM 
LD HL,#0000 
OUT (#99),A 
OR #40 
OUT (#99),A 
LD HL,#A000 
LD B,255 
LD C,#98 
This ex.  will not  work on the V9990, it should have read like
LD HL,#0000 
LD HL,#A000 
LD B,255 
LD A,(#0006) 
This  is smaller in memory and much nicer to look at. The speed
 should not be a problem as the BLOCK transfer is the same. 
The VRAM  problem is the SPRITE control since the bytes used in
 VRAM  are located  differently and 2 of the 4 bytes are
swapped  and 1 have different meaning. Not an easy one to
The last problem is that the V9990 does not have SCREEN 0-3. In
 the  V9990  BASIC  that  I now      have made  there is  a 64 
char  textmode, it  also works  in DOS. Program written in
BASIC with  no  'dirty' commands like 'VDP', 'BASE' and VPOKE
to the sprite  area would all work. 
Programs written  in XBASIC with the same limits will also work
 in my V9990 XBASIC version, when its complete. 
With  a few rules for software devellopers then future programs
 can work both on V9990 and on V9958. But as long as there is
no  MSX  with  ONLY  a  V9990  then  this  should  perhaps     
not  be  nessesary. 
The V9990  have some  modes not  mentioned in  the manual. They
Normal monitor: 
192 x 240 with 2-32k colours 
1024 x 212 with 16 colours (not sharp picture) 
VGA monitor: 
320 x 480 with 2 - 32k colours. 
160 x 480 --!!-- 
Some people asked me to write about the Interlace on the V9990.
The interlace is different from the one on the V9958. 1  page
non-interlaced will be the upper half of the picture in 
interlace  mode.   So  it  is  a  more    logically  and   
usefull  interlace. (No converting needed !) 
My  conclusion is  that the  V9990 is a very powerfull chip for
 both Games  and more  Serious programs. Personally I dont
think  that  there  will  be a  MSX with  just the  V9990 as 
too many  programmers  have not been, and will not be,
desciplined enough  to write  programs that  will work  on it. 
The ideal  solution  would be both V9958 and V9990
superimposed. However  I think that the V9990 are having too
huge a potential  to be ignored, even a 3.5 MHz MSX will be
able to gain from it. 
To the      people who  are 100%  against V9990 I just want to
ask:  When did You last use screen 1-4 ? 
 MSX should not be standing at the 1985 level for 10 more years.