WD9000 Pascal microengine schematics available

Jos Dreesen jos.dreesen at bluewin.ch
Mon Nov 9 13:39:47 CST 2015

On 09.11.2015 20:15, Eric Smith wrote:
> On Mon, Nov 9, 2015 at 7:04 AM, Brad Parker <brad at heeltoe.com> wrote:
>> I was wondering about software.  Is anyone planning to turn those schematics
>> into verilog?
> I'm working on dumping the microcode.

Your post overlapped with mine...

> The WD9000 board contains one WD chip for which no documentation is
> available, the WD2083U-04.

It is indeed an interrupt priority encoder.
I believe it is identical to the am25ls2513, as that is what is used in and early version of the schematics.


When I traced the signals it appeared to be
> a custom interrupt and DMA request prioritizer. That appears to be
> confirmed by the recently found WD9000 schematics (also on Bitsavers).
> I suspect that the WD2083 is a mask-programmed PLA.
> Other than the WD90 chipset and the WD2083, all of the chips on the
> WD900 board were readily commercially available and reasonably well
> documented.

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