On Wednesday 20 September 2017 10:29:08 Larry Martell wrote: > On Wed, Sep 20, 2017 at 5:09 AM, Gregory Ewing > > <greg.ew...@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 life. 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> -- https://mail.python.org/mailman/listinfo/python-list
