Subj : Re: what's classic now?
To   : Sean Dennis
From : Jeff Thiele
Date : Fri Jul 02 2021 09:29 am

On 01 Jul 2021, Sean Dennis said the following...
 SD>  JT> Here's the current state of my PDP-8 FPGA project:
 SD> 
 SD> That's really cool.  The oldest computer I've used is a VAX.

I worked with DEC Alphas for a few years, but have only encountered
architectures older than that as a hobbyist. SIMH will emulate a VAX, but the
problem is in acquiring the OS. HP (which bought Compaq, which bought DEC)
still requires a license to use VMS. Up until fairly recently they had a
hobbyist program through which one could get a non-commercial hobbyist
license for free, but they discontinued it. I'm not sure what, if anything,
took its place.

I completed all but the Extended Arithmetic Element opcodes yesterday; it was
much easier than I thought it would be.

I have, however, run into a small snag. The Mojo IO Shield uses all of the
available IO pins, so there are none left for peripherals such as an SD card
or a serial port. I figure I have 4 options:

1. Try to use IO pins for unused switches or LEDs, despite those components
being hardwired in;
2. Make a new fron panel from scratch with only the necessary components
(which I could, of course, make any size and with any layout that I'd like);
3. Forgo the front panel altogether; or
4. Move everything to an Alchitry Au/Au+ FPGA board which has more IO pins
and a virtually identical IO shield, but is physically almost ridiculously and
unusably small.

Jeff.

"For every complex problem there is an answer that is clear, simple, and
wrong." -- H. L. Mencken, who indeed was a racist thereby proving himself
right.

--- Mystic BBS v1.12 A46 2020/08/26 (Raspberry Pi/32)
 * Origin: Cold War Computing BBS (1:387/26)

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