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Topic: Capturing MUX'd BCD from ICL7135 (Read 332 times) previous topic - next topic

Grumpy_Mike

Quote
my model B was only 2MHz clock
Was it a US one?

PaulRB

Was it a US one?
No, I believe it was made at the ICL factory in Kidsgrove, where my father worked as an engineer for over 20 years, and I had a summer job for a couple of months while I was studying in Manchester.

Grumpy_Mike

Interesting, I got offered a job there after my post grad research, but I turned it down in favour of a lecturing career in Manchester.

I never knew the made a 2MHz one, I wonder why they did that?

PaulRB

#18
May 09, 2019, 01:21 pm Last Edit: May 09, 2019, 01:26 pm by PaulRB
I never knew the made a 2MHz one, I wonder why they did that?
I didn't know they made a 4MHz one. I remember the ram clock speed was 4MHz, so that the CPU and video chips could access it on alternating cycles, avoiding contention with each other.

EDIT: was that the "BBC Master Turbo" with the faster second processor?

Grumpy_Mike

Oh I never had one of those. Looks like they identified a bottle neck and sacrificed processor performance for graphics.  Maybe because it looked more impressive.

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