This article has been prompted by a
number of people asking about ROMs and
how to fit them. Please do not hold me
responsible for any damage you may do
to yourself or your computer after
reading this article! If you are unsure
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By C.J.Richardson. There are several different versions
of the BBC. Each has different slots
for ROMs. Some have ROM boards fitted.
This article will not attempt
explaining how to fit ROMs onto these
boards.
You may need to rearrange the order of
the ROMs in your machine.
ROMs may be removed by placing a
screwdriver under the end and gently
twisting. Move from one end to the
other, easing the ROM out a little at a
time. Be careful not to touch or bend
the legs.
There are two types of ROM that may be
fitted into your computer. They are:
1. Language (BASIC, WORDWISE etc)
2. Service (DFS, PRINTMASTER etc)
When the computer is switched on, it
looks to see what order the ROMs are
placed into the ROM slots. It starts
at the highest and moves down to the
lowest. The ROM in the highest slot
gets priority over ROMs in lower slots.
The language entered when the computer
is switched on will be the language in
the highest socket. So if for instance
you insert a WORDWISE ROM into a socket
higher than a BASIC ROM, then it will
be WORDWISE that you enter when the
computer is switched on.
If you have fitted service ROMs with
the same * commands, then the ROM in
the highest socket will take priority.
A link is a switch which tells the
computer how a slot is configured. For
more details, see each relevant
section.
A link comprises 3 small metal prongs
and a small piece of plastic with a
metal sleeve. The plasic will push over
2 of the prongs. Which 2 prongs it is
fitted over tells the computer how the
ROM slot is configured. If the 3 prongs
run from left to right, if the sleeve
is fitted over the first 2 prongs, then
the link is set WEST. If the sleeve is
fitted over the last 2 prongs then the
link is set EAST. The same convention
follows for links that run from top to
bottom (NORTH and SOUTH).
Each ROM has a notch at one end. If you
insert the ROM into a ROM socket the
wrong way around you are liable to
damage the ROM. A good guide is to look
at the other ROMs in the computer and
insert the ROM with the notch in the
same direction as the other ROMs.
Remove the cover. Remove the keyboard.
The sockets are to the bottom right.
There are five sockets. The left hand
one contains the Operating system and
is the highest socket. Normally BASIC
is fitted to the right of this. The
other three may or may not already have
ROMs fitted. You may interchange the
ROMs, but leave the far left hand one
(the operating system) where it is.
Remove the cover. The 6 sockets are to
the top left of the board. The top
right ROM of these 6 is the Operating
system AND BASIC (the ROMS on a BBC+
are 32K) this is the highest socket.
To the top left of the board there are
5 links. These links are each
associated with one of the other 5
slots.
Link Associated with Top 18 Top row, 2nd slot from left
15 Top row, left hand slot
12 Lower row, far right
11 Lower row, middle
Bottom 9 Lower row, left hand slot
The slot with the highest priority is
the slot at the top of the above list.
Set the links EAST for a 32 K ROM and
WEST for a 16 or 8 K ROM.
Remove the cover. The ROM slots are at
the right hand side. The slot with the
highest priority containing the
operating system, BASIC, ADFS and DFS
is at the top of the row of 4 slots.
The configuration links are links 18
and 19. These are situated to the left
of the slots. Link 18 is in line with
the lowest ROM slot. Link 19 is in line
with the slot below the BASIC ROM.
The link number is written on the
circuit board as "LK19" or "LK18".
For the top socket to recognise a ROM
inserted into it, you must switch link
19 EAST.
For the lower socket to recognise a ROM
inserted into it, link 18 must be EAST.
There are also 2 cartridge slots on the
Master. This enables you to put ROMs
into the cartridge and then push the
cartridge into place without having to
take your computer to bits.
Remove the cover. The sockets are
situated at the right hand side and run
from bottom to top in order of
priority. The Operating system, BASIC
and ADFS are fitted into the bottom
socket.
Link 11 is situated to the right of the
top socket. If this link is set SOUTH
then the computer will recognise a ROM
fitted in the slot just above the BASIC
ROM. If link 11 is set NORTH then the
computer will recognise hardware fitted
to the expansion connector on the right
hand side of the casing.