dkelvey at hotmail.com
Mon Jul 30 23:23:53 CDT 2007
>From: "Ethan Dicks" <ethan.dicks at gmail.com>
>On 7/30/07, dwight elvey <dkelvey at hotmail.com> wrote:
> > An alternative to switches is a diode ROM. You don't need too many
> > diodes if the system already has some ROM boot code and all you need
> > is a call routine.
>In the PDP world, there were diode bootstraps and rope-core
>bootstraps. Most DMA devices were smart enough on their own to easily
>load block zero into core at 0000 with little effort. I recall a
>PDP-11 bootstrap that depended on human reaction time being slower
>than the disk that could boot an RK06/7 in, essentially one word. You
>stuffed the right value into the CSR directly, then jumped to 0000000.
> Before you could type G 0000000 or whatever, the disk pulsed and the
>block loaded, leaving you a boot block to jump into. The full and
>proper auto-boot code wasn't even a dozen words anyway.
My IMSAI's disk controller boots the same way. I hit reset
and the disk spins. I have the switches set to zero and just
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