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Cyhist Apr 07 1997 E
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Date: Mon, 7 Apr 1997 15:41:44 PDT
Reply-To: "CYHIST Community Memory: Discussion list on the History of
Cyberspace" <CYHIST@MAELSTROM.STJOHNS.EDU> Sender: "CYHIST Community Memory: Discussion list on the History of
Cyberspace" <CYHIST@MAELSTROM.STJOHNS.EDU> From: David Wise <david_wise@PHOENIX.COM>
Subject: firing up old iron + venue suggestions
______________________________________________________________________
Community Memory: Discussion List on the History of Cyberspace ______________________________________________________________________
Most of my postings seem to start out as private replies. This is what I wound up with when I answered George at the American Computer Museum, who expressed amazement that I keep my 1620 running, and enthusiasm at my decision to will it to a museum.
While my interests coincide a lot with yours (all you on this list), some of what I have to offer (and need!) aren't relevant here. I want to get in touch with other keepers of still-running iron, to compare notes and scrounge spare parts. Does anybody know where I should ask? Surely I don't have the last running 1620! I want to play with it still, for years maybe, before I give it up. It'll be nice to have it on display, but I still think people would get a bigger kick out of seeing a museum piece that RUNS.
One man wants to write a 1620 emulator in C, and hopes that I can get some paper tapes onto floppy.
I'll do it, sometime. But here's the ticket if you want to go emulation-crazy. Do a 360/20 emulator, which can then run a 1620 emulator (which no doubt exists), which can then run a Bendix G15 emulator (which I have), which can then run a Bendix G15 program. I'm sure someone can come up with one.
The rest of this is sort of a continuation to my story of acquiring and restoring a 1620.
You have very solid reasons not to walk up to a piece of old equipment and just flip the switch, particularly with tube-era equipment. But it is possible to bring them back, if you take care.
In between the odd computer, I also collect vintage radios and test equipment. Every piece I have, works, but about half would have smoked if I hadn't gone through them first. Most tube equipment will have bad electrolytic filter caps, partly due to heat, partly from high-voltage stress. My Tektronix oscilloscopes were ok in that respect, surprisingly. They used premium parts, and it shows.
None of the 1620 power supplies is over 48V, and low-voltage electrolytics survive very well. Plus, the 1620 power supplies are fused, circuit-breakered, crowbarred, and interlocked so if anything trips, the mains shut down. I know it's not a fair comparison [with George's machine, untouched for 20+ years], since my machine had been occasionally powered on at least into the 70's, but I've never had a single power supply problem, nor any problem where something overheated and caught fire - never even a whiff of smoke.
Before I ever powered it up, I tested every SMS card, even measuring rise time and propagation delay. This revealed about a dozen bad transistors, which I replaced with modern units. I bench-tested all eight power supplies; they were fine. So I put it back together and plugged it in. Nothing, which is what I expected, since I had the main breaker open. I closed it. Bang-Hummmmm! I jumped, but it turned out to be normal; when a big relay closes, it makes a big noise. The hum came from a large transformer. The red THERMAL light was on. This is also normal. Although I knew nothing would happen, I went ahead and flipped the power switch without pressing RESET to kill the red light. Whirrrrr! the fans came on but nothing else. This was normal too. Some of the fans sounded pretty bad. I turned everything off and examined them. Half of the 1620's thirteen cooling fans were dead, mostly from worn-out bearings. I replaced them with good ones, rebuilding all the air filters at the same time, got brave, pressed RESET (Click! and the red light went out), and flipped the Switch.
Bang-Whirrr-Clickclickclickclick... White lights on the panel!. The bang was other big relays closing. The clicking came from a spinning cam that opens and closes the typewriter sequencing interrupters. In my excitement, I forgot an important fact and pressed START. Nothing happened. Oh, yes, you have to wait for the core memory to warm up to 104F. While I waited I played with the typewriter.
The only enabled keys were Tab and Return. This is normal. Tab worked so badly that I realized the typewriter was gummed up. I shut everything off and spent the next few hours cleaning the typewriter. Yuck, what a mess. When it was satisfactory I powered back up and waited ten minutes for the green POWER READY light. When it clicked on I forgot another important fact and pounced on START. The RUN light went on! But nothing else happened. Oh, yes, you have to have a program! (Remember, I was excited.).
I pressed INSERT. K-ChackTickTickTickTick... as the typewriter shifted into numeric and relays clicked in time with the interrupters, I entered my first program:
260000200003
I pressed RELEASE (K-Chack! and the ticking stopped), took a deep breath, and pressed START. The panel came alive as the 1620 cycled through all memory writing zeroes. I could hardly believe it. It was running! I pressed INSTANT STOP and RESET, and flipped the paper tape unit's power switch. Grrunnn! as the big motor spun up. I was surprised the lights didn't dim. I clumsily loaded the basic diagnostic tape, and entered my second program: 360002400300 4900828. START, and the tape started coursing past the read head, then stopped. Oh-oh, CHECK-STOP red light. And I spent the next hour calibrating the photodiodes. The next performance worked better: the tape kept moving right to the end, and the typewriter came to life. After a few garbled blotches on the paper, we stopped with another CHECK-STOP, and I spent another hour adjusting the typewriter (I had merely _cleaned_ it before). Third try was the charm, and I was treated to a rhythmic clatter as it printed a greeting. I pressed START again, and settled in to watch the hypnotic lightshow on the panel as my own piece of ancient IBM iron ran its diagnostic. It was the start of a long and happy relationship.
Over the years, another half-dozen transistors have failed. Each time, armed with scope and clip leads, I've found the trouble and fixed it. I continue to write and upgrade small programs. You might wonder why I do it,
when I could boot my PC and click on MS Developers Studio. I've asked myself that more than once. I think it gives me a feeling of groundedness, of having roots. I also think that my 1620 is a BETTER machine for the purpose of understanding what a computer is and how one works. More fun. A PC is a featureless box with gee-whiz on the screen, but kids are used to that, they see it on TV every day and become deadened to the wonder and complexity of what is going on behind the scenes. The complexity has become so daunting (and so cheapened) it's easier to ignore it. But you can walk inside the 1620 cpu. You have complete control and observation of every bit of the hardware. When you punch STOP it really stops, in its tracks. That's easy to understand compared to an OS's control-c trap. The panel lights tell the story of what the machine is doing, every little step of the way. You can't do that to a silicon die outside a research facility.
Plus, I like blinkenlights, and the smell of paper tape and old wire :-)
David Wise (david_wise@phoenix.com, in Portland, Oregon) Dinosaurette Keeper
-------------
Original Text
From: <Bitenbyte@aol.com>, on 4/4/97 3:33 PM: A working 1620!!!! Amazing!!!!!
No, ours does not work. I understand that it was last used over 20 years ago.
We typically do not turn on our machines as the power supplies, wiring, etc.
ages (especially in the machines from the 1930s and 40s. Best to preserve and
not gamble that a small fire or other electrical damage may occur.
However, having said that, I am amazed that you have a working 1620. Hats off!!!
We have no scematics or manuals. We saved this unit from the scrap heap by a
few days.
George K.
American Computer Museum
______________________________________________________________________
Reply-To: "CYHIST Community Memory: Discussion list on the History of
Cyberspace" <CYHIST@MAELSTROM.STJOHNS.EDU> Sender: "CYHIST Community Memory: Discussion list on the History of
Cyberspace" <CYHIST@MAELSTROM.STJOHNS.EDU> From: David Wise <david_wise@PHOENIX.COM>
Subject: firing up old iron + venue suggestions
______________________________________________________________________
Community Memory: Discussion List on the History of Cyberspace ______________________________________________________________________
Most of my postings seem to start out as private replies. This is what I wound up with when I answered George at the American Computer Museum, who expressed amazement that I keep my 1620 running, and enthusiasm at my decision to will it to a museum.
While my interests coincide a lot with yours (all you on this list), some of what I have to offer (and need!) aren't relevant here. I want to get in touch with other keepers of still-running iron, to compare notes and scrounge spare parts. Does anybody know where I should ask? Surely I don't have the last running 1620! I want to play with it still, for years maybe, before I give it up. It'll be nice to have it on display, but I still think people would get a bigger kick out of seeing a museum piece that RUNS.
One man wants to write a 1620 emulator in C, and hopes that I can get some paper tapes onto floppy.
I'll do it, sometime. But here's the ticket if you want to go emulation-crazy. Do a 360/20 emulator, which can then run a 1620 emulator (which no doubt exists), which can then run a Bendix G15 emulator (which I have), which can then run a Bendix G15 program. I'm sure someone can come up with one.
The rest of this is sort of a continuation to my story of acquiring and restoring a 1620.
You have very solid reasons not to walk up to a piece of old equipment and just flip the switch, particularly with tube-era equipment. But it is possible to bring them back, if you take care.
In between the odd computer, I also collect vintage radios and test equipment. Every piece I have, works, but about half would have smoked if I hadn't gone through them first. Most tube equipment will have bad electrolytic filter caps, partly due to heat, partly from high-voltage stress. My Tektronix oscilloscopes were ok in that respect, surprisingly. They used premium parts, and it shows.
None of the 1620 power supplies is over 48V, and low-voltage electrolytics survive very well. Plus, the 1620 power supplies are fused, circuit-breakered, crowbarred, and interlocked so if anything trips, the mains shut down. I know it's not a fair comparison [with George's machine, untouched for 20+ years], since my machine had been occasionally powered on at least into the 70's, but I've never had a single power supply problem, nor any problem where something overheated and caught fire - never even a whiff of smoke.
Before I ever powered it up, I tested every SMS card, even measuring rise time and propagation delay. This revealed about a dozen bad transistors, which I replaced with modern units. I bench-tested all eight power supplies; they were fine. So I put it back together and plugged it in. Nothing, which is what I expected, since I had the main breaker open. I closed it. Bang-Hummmmm! I jumped, but it turned out to be normal; when a big relay closes, it makes a big noise. The hum came from a large transformer. The red THERMAL light was on. This is also normal. Although I knew nothing would happen, I went ahead and flipped the power switch without pressing RESET to kill the red light. Whirrrrr! the fans came on but nothing else. This was normal too. Some of the fans sounded pretty bad. I turned everything off and examined them. Half of the 1620's thirteen cooling fans were dead, mostly from worn-out bearings. I replaced them with good ones, rebuilding all the air filters at the same time, got brave, pressed RESET (Click! and the red light went out), and flipped the Switch.
Bang-Whirrr-Clickclickclickclick... White lights on the panel!. The bang was other big relays closing. The clicking came from a spinning cam that opens and closes the typewriter sequencing interrupters. In my excitement, I forgot an important fact and pressed START. Nothing happened. Oh, yes, you have to wait for the core memory to warm up to 104F. While I waited I played with the typewriter.
The only enabled keys were Tab and Return. This is normal. Tab worked so badly that I realized the typewriter was gummed up. I shut everything off and spent the next few hours cleaning the typewriter. Yuck, what a mess. When it was satisfactory I powered back up and waited ten minutes for the green POWER READY light. When it clicked on I forgot another important fact and pounced on START. The RUN light went on! But nothing else happened. Oh, yes, you have to have a program! (Remember, I was excited.).
I pressed INSERT. K-ChackTickTickTickTick... as the typewriter shifted into numeric and relays clicked in time with the interrupters, I entered my first program:
260000200003
I pressed RELEASE (K-Chack! and the ticking stopped), took a deep breath, and pressed START. The panel came alive as the 1620 cycled through all memory writing zeroes. I could hardly believe it. It was running! I pressed INSTANT STOP and RESET, and flipped the paper tape unit's power switch. Grrunnn! as the big motor spun up. I was surprised the lights didn't dim. I clumsily loaded the basic diagnostic tape, and entered my second program: 360002400300 4900828. START, and the tape started coursing past the read head, then stopped. Oh-oh, CHECK-STOP red light. And I spent the next hour calibrating the photodiodes. The next performance worked better: the tape kept moving right to the end, and the typewriter came to life. After a few garbled blotches on the paper, we stopped with another CHECK-STOP, and I spent another hour adjusting the typewriter (I had merely _cleaned_ it before). Third try was the charm, and I was treated to a rhythmic clatter as it printed a greeting. I pressed START again, and settled in to watch the hypnotic lightshow on the panel as my own piece of ancient IBM iron ran its diagnostic. It was the start of a long and happy relationship.
Over the years, another half-dozen transistors have failed. Each time, armed with scope and clip leads, I've found the trouble and fixed it. I continue to write and upgrade small programs. You might wonder why I do it,
when I could boot my PC and click on MS Developers Studio. I've asked myself that more than once. I think it gives me a feeling of groundedness, of having roots. I also think that my 1620 is a BETTER machine for the purpose of understanding what a computer is and how one works. More fun. A PC is a featureless box with gee-whiz on the screen, but kids are used to that, they see it on TV every day and become deadened to the wonder and complexity of what is going on behind the scenes. The complexity has become so daunting (and so cheapened) it's easier to ignore it. But you can walk inside the 1620 cpu. You have complete control and observation of every bit of the hardware. When you punch STOP it really stops, in its tracks. That's easy to understand compared to an OS's control-c trap. The panel lights tell the story of what the machine is doing, every little step of the way. You can't do that to a silicon die outside a research facility.
Plus, I like blinkenlights, and the smell of paper tape and old wire :-)
David Wise (david_wise@phoenix.com, in Portland, Oregon) Dinosaurette Keeper
-------------
Original Text
From: <Bitenbyte@aol.com>, on 4/4/97 3:33 PM: A working 1620!!!! Amazing!!!!!
No, ours does not work. I understand that it was last used over 20 years ago.
We typically do not turn on our machines as the power supplies, wiring, etc.
ages (especially in the machines from the 1930s and 40s. Best to preserve and
not gamble that a small fire or other electrical damage may occur.
However, having said that, I am amazed that you have a working 1620. Hats off!!!
We have no scematics or manuals. We saved this unit from the scrap heap by a
few days.
George K.
American Computer Museum
______________________________________________________________________
