I’m wondering what has been added to this system in photo 2 can anyone shed any light on this for me many thanks
It looks like a home made add-on sideways ROM board, but the best place to ask is very probably the stardot forums…
Thanks Gordon much appreciated
If the imprint “8036” on the chip at the top left of the board is a date code, this might be a rather early one.
The 74ls154 is simply a 4 → 16 decoder - which would be needed as the Beeb can have up to 16 sideways ROMs. the other - the '245 is a bi-directional bus transceiver. (buffer).
These may not be out of place in some hobby enthusiasts collection - so personally I’d not be overly concerned about the date codes, especially if this is a home-made board. The Beeb was announced in 1981 but wasn’t generally available until 1982.
The Beeb came with 4 slots on-board for sideways ROMs (which all occupied address $8000 through $BFFF) but very quickly 3rd party add-on boards were produced firstly for ROMs (or EPROMs) then RAM.