36bit still in use ?

Rich Alderson RichA at LivingComputerMuseum.org
Mon Dec 1 14:47:52 CST 2014

From: Eric Smith
Sent: Monday, December 01, 2014 4:05 AM

> On Mon, Dec 1, 2014 at 4:57 AM, Lars Brinkhoff <lars at nocrew.org> wrote:

>> Rich Alderson <RichA at LivingComputerMuseum.org> writes:

>>> I worked at XKL for 10 years before coming to my present job 11
>>> years ago.  Putting the Toad-1 into an FPGA was an experiment when I
>>> left.

>> It was?  During my stint at XKL, I was told the Toad-1 I was working
>> with was an FPGA implementation.  Maybe it was an experiment, but it
>> seemed to work pretty well.  But then, I was a telecommuter, so maybe
>> some information was jumbled in long-distance transmission.

> You guys probably have more information about this than I do, but my
> understanding was that the Toad-1 CPU required multiple FPGAs, CPLDs,
> and other logic, while the Toad-2 CPU is a single FPGA.

Lars, Eric is correct.  The Toad-1 is a multi-board computer system (at
minimum, the XKL-1 CPU, one XMG-1 memory, one XNI-1 Ethernet interface,
and one XRH-1 SCSI interface, in a 7-slot backplane).  Each board used
several programmable parts, from Altera and Xilinx.  In particular, the
CPU was a pair of Xilinx parts for the microcode engine, with an AMD
2900 family sequencer (I forget the particular part number).

The Toad-2 (and the 1U rack mount unit is *not* a Toad-2, but it does
contain two of them, thus the label) is a single FPGA implementation of
the Toad-1 (mutatis mutandis: no SCSI, but it talks to SD cards, for


Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134

mailto:RichA at LivingComputerMuseum.org


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