MSX Computer Magazine				  14 October 1991
P.O. Box 4525
1000 CM  Amsterdam
The Netherlands


Uwe Schr”der
Wannerstrasse 57
D-4650	Gelsenkirchen
Germany


Subject: SCSI software for MSX Turbo-R


Dear Mr. Schr”der,

  Herewith  I  send you  a diskette  containing a  dissembled and 
patched version  of your SCSI Harddisk interface software. I made 
some  changes in  it, so that it should be booting on MSX Turbo-R 
computers without  an external DOS2 cartrigde installed. However, 
there  are some  problems -  probably in  the hardware	- which I 
cannot	solve.	Details  of  this problems  are discussed  below. 
Please have a look at my patches, I suppose they can be useful.

  More	and more  clients of  the MSX  Computer Magazine who have 
bought a  HSH Harddisk interface, would like to use it with their 
Turbo-R computers. We would like to give these people the service 
they deserve.

  Also, it  would be  appreciated very much, if you could help us 
out  of this problem. I understood that you already made your own 
version of  the SCSI  software for Turbo-R computers. If the proú 
blem  can be  fixed by	simply replacing  the EPROM  in the  SCSI 
interface, we would very glad hearing from you.

  If  you wish,  MSX Computer  Magazine is  prepared to  have the 
updated EPROM's developed and distributed under it's own name. In 
this way, you do not have to break your license agreement to HSH.


Hoping to hearing from you soon,




			Ries Vriend

The story of the SCSI patch
===========================

  For testing  purposes, the  patched software	was loaded into a 
battery  backed-up static RAM cartridge, which was then installed 
in one	of the slots of a MSX Turbo-R computer. The original SCSI 
HD-interface was connected in the other slot. This way, the hardú 
disk booted fine without an external DOS2 cartridge being instalú 
led.

  Then, I had the software programmed into an 256 kBit EPROM. The 
software was placed in both pages of 16 kB of the ROM, so that it 
could  safely be replaced with the original 128 kBit EPROM in the 
SCSI interface	cartridge. It  works fine on an Philips 8245 MSX2 
computer,  with a  DOS2 cartrige  installed in lower- or a higher 
numbered slot  than the slot of the SCSI-interface. When the DOS2 
is in slot 1 and the SCSI in slot 2, the HD boots as partition A: 
and  B:, the  floppies are  C: and D:. When the DOS2 is in slot 2 
and the  SCSI in slot 1, the HD boots as partition C: and D:, the 
floppies are A: and B:. So that works great too.

  When only the SCSI interface is installed and no DOS2 cartrige, 
the computer boots MSX-DOS1 and the HD will boot as partition C:. 
But very  often, the computer is hanging after the boot-procedure 
of  the Main-ROM.  First the  MSX-intro screen	appears, then the 
screen is  cleared and	the SCSI-intro	text should be coming up. 
But in about half of the times, the computer hangs at this moment 
and screen stays black. But once the boot procedure succeeds, the 
HD works fine and there's not a single problem in accessing it.

  So that  was the  story for  an 8245	or 8280  and probably all 
other  MSX2 machines.  On MSX Turbo-R, my - preproducion model of 
the  -	SCSI  interface  doesn't boot,  neither with  nor without 
MSX-DOS2  cartridge  installed.  A  `preproduction model'  can be 
recognized by it's print, which shows that all 50 pins of the MSX 
slot-connector have  been rerouted  manually to the other side of 
the  print. The  newer models  of the  SCSI interface which where 
delivered with	the HSH  Hammer system, have this error corrected 
by a completely different print lay-out.

  The `new' interface can boot on a Turbo-R, only when a MSX-DOS2 
cartridge  is installed in slot 1. This is also the case when the 
patched  software  is installed  in the  SCSI interface.  Without 
extra DOS2  cartridge, the  Turbo-R hangs just after the MSX logo 
has  disappeared from  the screen.  This is very strange, because 
the patched software was not giving any problem when it was bootú 
ed from a static RAM cartridge.

The End.
