Even Older Man Yells At Whippersnappers
On Wednesday 20 September 2017 10:29:08 Larry Martell wrote:
> On Wed, Sep 20, 2017 at 5:09 AM, Gregory Ewing
> <greg.ewing at canterbury.ac.nz> wrote:
> > Never mind that fake assembly rubbish, learn a real assembly
> > language! And hand-assemble it and toggle it into the front
> > panel switches like I did!
> 1979, I was working at Bausch and Lomb in Rochester NY. We had a 16
> bit Data General Nova 'Minicomputer'. It had 4 registers, called
> accumulators. It had 16 front panel toggle switches, one for each bit,
> one that said 'deposit', and one that said run. It had a dial with
> stops for AC0, AC1, AC2, AC3 (for the 4 accumulators), PC (program
> counter), address and contents.
> When you powered up the machine it did not boot. You had to hand enter
> a short bootstrap program in binary. Do to this you had to turn the
> dial to address, key in a 16 bit address, click deposit, turn the dial
> to contents, key in a 16 bit line of assembly code, click deposit, and
> repeat this for each line of code (there were like 5 or 6). Then key
> in the address of where you wanted to run from turn the dial to PC,
> deposit, and click run. Any mistake and it would not boot. Often took
> 3 or 4 tries.
> After a few weeks of this I was sick of it. I had the boot code burned
> into an EEPROM (which I had to send out to be programmed). Then I
> build a very small wire wrapped board with the EEPROM and an
> oscillator and few TTL chips. I tapped into the 5V power on the CPU
> board and used the leading edge of that to trigger a one shot which
> 'woke up' my circuit, and caused it to clock out the code from the
> EEPROM and load it to the appropriate place, set the program counter
> and start the program. I drilled holes in the CPU board and mounted
> this with little plastic standoffs.
> I did this all on my own, coming in on the weekends, without company
> approval, and when it was working I showed my boss. He was blown away
> and he was sure we could patent this and sell it. He had me formalize
> the design, write it up, have an actual PCB made, go to the company
> lawyers, the whole 9 yards. Then Data General announced the new
> version of the Nova .... with auto boot.
Chuckle, love it Larry. But then I am sure it was not that much of a
problem for you.
That super elf? Used a broadcast audio cart in an old machine whose
capstan was badly worn so it played a regular cart at about 90% speed
for its non-volatile memory. Didn't bither the elf a bot, never had it
fail to load and run the next copy of my program. I had saved 4 or 5
copies on a 2 minute cart. Then did another for backup, and a 3rd cart I
took home. Fast fwd to 2017, it and a paper copy of that machine code is
on the top shelf here in this room. Yeah, I've had packratitis all my
Cheers, Gene Heskett
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>