Storage Cost Calculation

Steven D'Aprano steve+comp.lang.python at
Sun Sep 28 04:47:05 CEST 2014

Chris Angelico wrote:

> The RAM was presumably the only difference between the two models, so
> as long as Model A cost at least £100 (which seems likely; a bit of
> quick Googling suggests that it may have been of the order of £400), a
> £100 difference can plausibly be called the price of the RAM.

Hah! I read MRAB as saying the *RAM* came in two models, "Model A RAM"
and "Model B RAM". I wondered why they didn't just say "16K" versus "32K",
but it was the 1980s, who knows why people did anything back then...

But no, you can't put the £100 difference down to the price of the RAM even
if RAM were the only difference between the two model Micros. There's not
enough information to tell how much of that £100 represents the cost of
RAM, and how much is pure profit on the part of the vendor, Acorn. In fact,
there were considerable differences apart from RAM:

The Model B supported more graphics modes, had a six-pin DIN connector for a
monitor (both the A and B had UHF output for connecting to a television,
but only the B supported a dedicated monitor), had support for an optional
floppy disk controller and even an optional hard drive controller. It also
had RS-232 and Centronics parallel interfaces, a 20-pin "user port" for
I/O, and even support for a second CPU! The Model A didn't support any of

At the time, the BBC Micro memory was (I think) expandable: the Model B
could be upgraded to 128K of memory, double what Bill Gates allegedly said
was the most anyone would ever need. (He probably didn't say that.) So what
we need is to find out what an upgrade would have cost.


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