Date   : Mon, 23 Jan 2012 16:24:04 +0000
From   : stuart@... (stuart)
Subject: Help figuring out ICs and ROMs for BBC (B or Master)

> I've gathered that the ICs with a "window" are EPROMS

Yup.

> that the SAA5050 are text graphics chips,

Well they are teletext chips for mode 7 on the BBC.

> but the rest of the ICs are unknown to me.

The following are all still available over the counter:

All the smaller chips (and one larger one SN74154) that typically have
the number 74 on them are logic chips. Worth keeping as spares should
you be interested in fixing a BBC or similar aged computer, or if you
still like to use TTL in designs.

The chips with 8 legs are 741 op-amps.

The AM26LS31 is a line driver that I think is used in the Econet
circuit.

I do not think the following are easily available.

The TBA720 is a demodulator chip used in TV sounds stages and the like.

The WD1770s' are part of the floppy disk sub-system used in the likes
of the BBC B+.

The R6502A is a CPU as used in a BBC B.

I am not sure but IIRC the HD486A21P is a video ULA.

There were a couple on the 3rd picture I could not read so I have no
idea what those ones are.

HTH,

-- 
Stuart
Microsoft - products from convicted criminals