[BBC-Micro] Reversing the Tube ULA (destructively)

John Kortink kortink at inter.nl.net
Tue Oct 26 10:13:17 BST 2010


On Tue, 26 Oct 2010 09:23:43 +0100, Pete Turnbull
<pete at dunnington.plus.com> wrote:

>[...]
>
>The original Tube ULA was made by Ferranti (part no 201,605).  The 
>second version is an AMD chip (2201,266) which isn't an exact 
>replacement, nor is it pin-compatible.

Actually it is, with one exception : power. The Ferranti
requires two power supplies. The AMI (not AMD !) only one,
and if used like a Ferranti, it shorts out the two power
supplies and will eventually go up in smoke. If you give
it just the one power supply, it's fine in any 'Ferranti'
environment.

There's one more difference. The Ferranti cuts out at
roughly 3.5 MHz access speed. The AMI only at roughly
8 MHz.


John Kortink

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