Date   : Wed, 27 May 1998 14:20:52 BST
From   : Chris Thornley <osu036@...>
Subject: High density

There is an alternative to messing around with disc controllers. If the BBC
scsi interface can handle it TEAC 
produce some SCSI HD floppy drives. The information below is cut out of some
information I have. To format a 
disk and read and write etc you use scsi commands.

       Getting SCSI floppies & docs
       ----------------------------
       There are several different TEAC SCSI JS floppies available. The
    names are of the form FD-235JS-xxx. The xxx in the name designates the
    model of drive which the FC-1 controller board is strapped to. I have
    seen mention of 300/302/401/650 / 660-U.

       FD-235HS-302    3.5" 1.44Mb SCSI floppy (using FC-1)
       FD-235JS-401    3.5" 2.88Mb SCSI floppy (using FC-1)
       FD-55GS-704     5.25" SCSI floppy (using FC-1)


       The TEAC drive documentation available is:

    FC-1 Spec      Part number 10530468-01 @ US$20.00
    FD235J-650 Spec Part number 10530403-50 @ US$ 7.00
    FD235HS-300Spec Part number 10530472-02 @ US$ 7.00
    FD235JS-   Spec Part number  ?         @ US$ 7.00

       They also want $4.00 shipping & handling per item.

       The SCSI specs are available from the ISO rep in each country.
       The easiest & most useful way to get hold of the SCSI
    specs is downloading from the SCSI BBS. As far as I know, there is no
    internet site which carries these docs.
       SCSI BBS  (316)-636-8700.

If anyone thinking of rewriting a fileing system I think a good idea is to
seperate the filesystem rom into two. 
i.e The filesystem rom in a BBC handle to major functions a) Comunicate with
the hardware + and provide an 
interface the filesytem b) Is a filesystem interepretating and and preparing
information in a standard format.

1) If a device or direct acces rom could be produced which provides standard
comands / calls  and even low 
level calls so hardware need not be adressed. This could be changed depending
what hadware you have or 
there could be some sort of auto detect to check which hardware present and
therfore only provide certain 
functions.

2) A filesystem rom which comuniactes with the direct access rom in a standrd
way so if the hardware changed 
the whole filesytem does not have to rewritten. Also as the filesytem will
only have to do one thing more code 
for multiple filesystems could be squezed on the rom.

Is there anyway to provide a fully fledge bus for the bbc with access to
all its signal and adresses. i.e 
practically the same as the Apple II card conector which is ideal. Then you
could produce three controllers on a 
card pr what ever. Or implement Universal Serial Bus.

Bye
Chris


               />      Christopher J. Thornley is OSU036@...
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