Date : Wed, 11 Jun 2003 08:13:47 +0100 (BST)
From : Peter Turnbull <pete@...>
Subject: Re: Sideways RAM designs
On Jun 11, 5:01, Mike Tomlinson wrote:
> In article <20030605222607.I3540@...>, James
> Fidell <james@...> writes
> >I have here on my desk an ATPL "Sidewise" sideways ROM/RAM board
> >carrying two 6264 chips and 12 ROM sockets. Without opening a Beeb
> >it looks like it mounts into one ROM socket (IC51?) and into the
> >for IC73 (whatever that is).
> Unplug the ADC chip and the OS ROM, insert the Sidewise board into
> vacated sockets, then plug the OS and ADC chips back into the same
> positions on the Sidewise.
You also need to remove the link from the lower half of S21 and plug
the two flying leads onto the two pins (E1, usually red, on the right,
the other, usually blue, on the left). This is where the Sidewise
board gets the additional signals to decode 16 instead of just 4 ROMs.
Usually you have to pull the link and fit the wires before plugging
the Sidewise board in, because you can't reach them afterwards.
You normally also have to carefully bend the two power connectors near
the ADC chip, becasue on most machines, they stick up too high.
Almost all Sidewise boards came with a 24-pin turned-pin socket fitted
to the pins for the ADC socket, to make it slightly higher at the back.
It's often missing on second-hand boards. It may not be essential,
but it's best to have it, to prevent anything shorting.
You probably also want to move BASIC and your highest-priority filing
system ROM(s) to the Sidewise, as the motherboard sockets have lower
> Manual at:
> If this doesn't help you identify where to reconnect the broken red
> on the Sidewise, I can unpack my Beeb and have a look for you.
I didn't see the original post, but a Sidewise board normally has a red
wire and a blue wire, which are the two flying leads mentioned above.
Near the bottom left corner you'll see four diodes labelled D1...D4
and a resistor, R7. Now look on the underside. The leftmost ends of
those components are connected together, and also connected to the
leftmost of a pair of smal solder pads. The blue wire goes to the
leftmost of this pair, and the red wire to the other one.
Pete Peter Turnbull
University of York