Date   : Wed, 01 Jun 2005 00:13:31 +0100
From   : "BeebMaster" <beebmaster@...>
Subject: Re: Zif thingy

I think the original idea for the ROM socket on the BBC keyboard was part
of the Speech Upgrade, to
allow you to put in additional Phrase ROM cartridges, although none were
ever issued.  The only
Phrase ROM is the Kenneth Kendall one which fits on the BBC B/B+ motherboard.
 It could also
apparently be used for "serial ROMs" (I'm not sure how these differed from
"paged ROMs" which is
how the standard BBC ROMs are known because they are paged in and out of
the same bit of the memory
map depending on which one is being used at the time) but I don't think any
of these were ever
produced.  The socket was (I think) a connector suitable to take a little
cartridge with an edge
connector rather than being a 28-pin ROM socket.  This was connected to the
BBC motherboard by a
10-way ribbon cable going from a plug on the BBC keyboard to the right of
the speaker which would
be added as part of the speech upgrade to the plug on the motherboard just
below the speech chips.

Viglen brought out their cartridge system which, similar to what Sprow has
described below, was a
ribbon cable that plugged into a spare ROM socket on the motherboard and
then went round to the
keyboard socket hole ending in an edge connector for the black Viglen cartridges.

I have found this system very unreliable as I think the length of the ribbon
cable causes problems
with the Beeb's timings giving unpredictable results.  For a long time I
had a ROM Box connected to
my Master 128 (similar thing with a ribbon cable connecting either to one
of the motherboard ROM
sockets or to an empty socket in a ROM cartridge as I had it, and ending
in a box which could take
8 ROMs and a dial to select which) but I recently removed it because it made
the Master very
unstable.  And of course turning the dial on the ROMBox and then trying to
type something before
pressing CTRL-BREAK was always amusing...

Best wishes,


Ian
----- Original Message -----
From: Sprow
To:  "BBC Mailing List" <bbc-micro@...>
Sent: Tue, 31 May 2005 20:19:47 +0100
Subject: Re: [BBC-Micro] Zif thingy

In article <06a001c5660b$f5a594b0$0400a8c0@...>,
   Matt Cocker <themicrouser@...> wrote:
> Hi Aaron,
>
> We get everywhere don't we.
>
> I do not have a spare Zif socket (that is what the suppliers called them) 
> but I can tell you that it connects to one of the spare sockets on the 
> motherboard so that you can swap roms (with the machine switched off!).

Zero insertion force socket.

They can be fairly easily made with the following
 1x ZIF socket
 1x ribbon cable
 1x crimp on IDC to DIL28 header
 1x decoupling cap

A small piece of stripboard is also handy just to give some more surface
area with which to glue to socket into the ashtray,
Sprow.