Date   : Sat, 02 Oct 2004 09:42:07 +1200
From   : Bill Keesing <zz9pluralzalpha@...>
Subject: Re: FW: BBC Master Compact cabling info

At 01:15 a.m. 30/09/2004, Jonathan Graham Harston wrote:
> > Message-ID: <200409290408.i8T48akf020856@...>
>
>Bill Keesing <zz9pluralzalpha@...> wrote:
> > and a ROM in the frontmost socket (IC49) with a sticker that reads
> >
> > 537X
> > 0004
> >
> > Could someone please elighten me as to what this ROM is.
>
>That's probably the Master Compact 64K system ROM.
>
> > I can see a WD1772 chip just below the disc interface so I am assuming the
> > machine is ready to take a disc drive. All I need is the ADFS ROM,
> > correct?
>
>If it is a Master Compact, ADFS is already in the system ROM. By default,
>the Compact has: BASIC ADFS UTILS MOS

Cool. Thanks for that. I was worried I'd have to source those ROMS from 
someone.

>The ROM sockets are laid out as:
>
>   ROM 3
>   ROM 2
>   ROM 8
>   ROM 0,1
>   ROM 13,14,15,MOS
>
> > has an electronic copy could they please email them to me. I am after the
> > pinouts for the power supply and the disc interface.
>
>Power supply: Centre +9v, Outer 0v. BUT CHECK THIS as I may have got this
>wrong.

The voltage is wrong. It says 5 volts DC @ 2 amps max. I was planning to 
have a fly lead from the PS I use for the floppy drive(s).

>  Check the PCB tracking to confirm this. I have replaced the PSU
>socket on my Compacts with a connector that I plug a disk drive PSU
>connector into.
>
>Disk Drive:
>  1       ~INDEX
>     14       0v
>  2       ~DS0
>     15       0v
>  3       ~DS1
>     16       0v
>  4       ~DS2
>     17       0v
>  5       ~MOTOR ON
>     18       0v
>  6       ~DIR
>     19       0v
>  7       ~STEP
>     20       0v
>  8       ~WRDATA
>     21       0v
>  9       ~WRGATE
>     22       0v
>10       ~TRK0
>     23       0v
>11       ~WRPROT
>     24       0v
>12       ~RDDATA
>     25       0v
>13       SIDE
>
>You can connect a standard 34-way disk drive lead by omitting pins 1-7,
>pin 8 onwards goes to the 25D pin 1 onwards, and pin 33-34 are omitted:
>
>               1
>               to
>               7
>        1 ---->8
>   25D  to     to  34W IDE
>        25---->32
>               33
>               34

Thanks heaps. I think I'll get one of those rounded floppy cables, an IDC 
25pin D shell and hook it up that way since it is that nicely set up. Now 
all I need is one of those odd DIN plugs for the RS232 cable. I don't 
suppose one of you fellow Auckland Beeb enthusiasts can tell me where I can 
find one in Auckland. I have looked in DSE's and Jaycars web sites and they 
both sell an 8 pin DIN plug with the centre pin and I wondered if anyone 
had any experience chopping the excess pins off one of those to convert it 
to the RS232 style on the Beeb.