I’m wondering what has been added to this system in photo 2 can anyone shed any light on this for me many thanks
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It looks like a home made add-on sideways ROM board, but the best place to ask is very probably the stardot forums…
-Gordon
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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.
-Gordon