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Forum Index : Microcontroller and PC projects : 8-Bit computer made from 74HC series...
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9751 |
Yee Gods.....  74HC based 8-bit computer No, I don't think I want to go there with all those link wires and breadboards.... Smoke makes things work. When the smoke gets out, it stops! |
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Revlac Guru  Joined: 31/12/2016 Location: AustraliaPosts: 1204 |
 Best RATS NEST I Have seen yet.  Cheers Aaron Off The Grid |
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CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2171 |
truth be, it could be anything under that rat's nest... bet it's a Pi |
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goc30 Guru Joined: 12/04/2017 Location: FrancePosts: 435 |
when I see this computer, I remember Bill Gates "If Ford had kept up with technology like the computer industry has, we would all be driving $25.00 cars that got 1,000 miles to the gallon. |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4126 |
I think it was GM, not Ford. In response to Bill's comments, General Motors issued the following press release - If GM had developed technology like Microsoft, we would all be driving cars with the following characteristics - 1. For no reason whatsoever, your car would crash twice a day. 2. Every time they repainted the lines in the road, you would have to buy a new car. 3. Occasionally your car would die on the freeway for no reason. You would have to pull over to the side of the road, close all of the windows, shut off the car, restart it, and reopen the windows before you could continue. For some reason you would simply accept this. 4. Occasionally, executing a maneuver such as a left turn would cause your car to shut down and refuse to restart, in which case you would have to reinstall the engine. 5. Only one person at a time could use the car unless you bought "car NT", but then you would have to buy more seats. 6. Macintosh would make a car that was powered by the sun, was reliable, five times as fast and twice as easy to drive - but would only run on five percent of the roads. 7. The oil, water temperature, and alternator warning lights would all be replaced by a single "General Protection Fault" warning light. 10. The airbag system would ask "are you sure?" before deploying. 11. Occasionally, for no reason whatsoever, your car would lock you out and refuse to let you in until you simultaneously lifted the door handle, turned the key and grabbed hold of the radio antenna. 12. GM would require all car buyers to also purchase a deluxe set of Rand McNally road maps (now a GM subsidiary), even though they neither need nor want them. Attempting to delete this option would immediately cause the cars performance to diminish by 50% or more. Moreover, GM would become a target for investigation by the Justice Dept. 13. Every time GM introduced a new car, car buyers would have to learn to drive all over again because none of the controls would operate in the same manner as the old car. 14. You'd have to press the "Start" button to turn the engine off. found at whydidthechickencrosstheroad.org - attributed to David Atkinson John |
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| Paul_L Guru Joined: 03/03/2016 Location: United StatesPosts: 769 |
15. When you changed your shoes you would have to reinstall the fuel injection computer. Paul in NY |
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palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 2006 |
The picture could be Bill working on Win 11. Paul. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
This brings back memories. In the very early 70's I was service manager for Roche Biomedical Melbourne, and Roche UK developed a patient monitoring system that had a cathode ray tube with on screen display of ECG, blood pressure, and respiration. Nothing particularly clever about that, except it also had an on screen alphanumeric raster scan readout on one side of the screen, which was revolutionary in that day and age. There was a massive circuit board full of 74 series TTL chips, no microprocessor, but an eight bit bus system that everything hung off. It had all the usual things, ROM, RAM, IO, AtoD converters and worked sort of like a hardware processor, but it was just a simple state machine with top down programming. No branching or conditional jumps, just a hardware program counter that cycled through step by step, then repeated in an endless loop. We were all going like wow, this is real state of the art, which it probably was back then. Pretty laughable now though. Within a year they redesigned it with a real microprocessor. But it made a very interesting introduction into a whole new world of some strange new process called software. Cheers, Tony. |
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| tinyt Guru Joined: 12/11/2017 Location: United StatesPosts: 470 |
Been thru the following: Holerith card technology: IBM card punch, verifiers, sorters, collators, accounting machines, etc. IBM Mainframes: 1401, System 360, System 370. Memories: magnetic core (read/write, sense/inhibit), IBM card capacitor read only storage (C-CROS), transformer read only storage (TROS), and then the solid state memories. IBM Operating systems, etc.: BOS, TOS, DOS, OS360, MFT, MVT, VS1, MVS, VM370, CMS, TCAM, VTAM, DL/1, CICS, IMS. Does not mean I still remember them. And I am also wondering why I am still above the ground. |
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| Paul_L Guru Joined: 03/03/2016 Location: United StatesPosts: 769 |
@tinyt WOW! I've finally found someone here who has been above ground almost as long as me! I started with the IBM 701. I never did work with C-CROS. I loved all of those JOINS in OS360. Paul in NY |
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| tinyt Guru Joined: 12/11/2017 Location: United StatesPosts: 470 |
As far as I know and remember C-CROS is the first read only memory for storing micro-code. Its first use is on the IBM-360 model 30. They used special holerith cards which has conductive pads at the intersections of the matrix of 80 columns and 12 rows. The pads are in between the rows that the card punch normally will punch the rectangular holes. Un-programmed C-CROS has all the pads of each rows connected together by conductive material. The top of each pads have short conductive lines that connect to a conductive line running horizontally for each row. There are also pads at one end of the card for driving the rows with drive pulses. All of these are between the punch out areas. To program a C-CROS, they use a regular card punch to cut the short conductive lines. Pads that are left connected now act as one side of the capacitor that gets sensed by another pad on a large board which has pads covered with thin insulation that are aligned with all pads of the special holerith cards. So the board pad-insulation-pad on card forms a capacitor. I don't remember now how large this board is to accomodate the number of special holerith cards. The holerith cards are pressed against the big board with air bladders. So if something is leaking the built-in air compressor will operate once in a while. The IBM-360 model 30 can be ordered with emulation mode for the 1401. Basically it has two C-CROS assemblies one for 360 mode microcode and another for 1401 mode microcode. My memory is very poor now, I don't know/remember JOINS. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Anyone remember magnetic core RAM ? Or bubble memories ? When I worked at the ABC we had a light dimmer control desk with one of those magnetic core memories. Many hundreds of tiny toroidal cores with wires threaded through in a matrix configuration. Horrible thing, it did not last very long. Cheers, Tony. |
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| tinyt Guru Joined: 12/11/2017 Location: United StatesPosts: 470 |
Yup on magnetic cores. The ones I worked on, they are in stacks of 9, the ninth is for parity. The stack has a heater underneath which has to be controlled. If the stack temperature is too hot, they will pick up bits, too low, they will drop bits. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Amazing when you think back how electronic and computer technology has advanced in just our own lifetime. Its been a great time for us old timers, I think much of the fun has gone out of it now. When I was a teenager even making a telephone call interstate was a big drama, and building my own amateur radio equipment to talk to people overseas a real thrill. Now any kid with the internet or a mobile phone can contact anywhere in the world so easily without even thinking about the technology behind it all. Cheers, Tony. |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4126 |
I (dimly) recall being amazed when memory dropped to only £1 (about $1.50) a bit. I used to be able to punch cards on a hand punch. Horrors. Then there was patching punched tape. Don't miss that. Anyone else used to cut a few feet off a reel of (magnetic) tape? (Because it got used most so was worn.) Oh - and the joy at having access to a machine with a 64K disc. (Fixed disc, mind you, none of that exchangeable stuff.) John |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9751 |
Magnetic core memory is certainly before my time, but I have seen plenty of videos of it, and it is a thing of beauty up close. Imagine having to thread one of those things up! Now you can buy an Intel 256GB SSD with 3D2-TLC technology for $85 - and that's not even the cheapest in the range! (128GB same series for $57!) 500MB read AND write speed, 75,000 IOPS random read, 85,000 IOPS random write. ....oh how far we have come.... Smoke makes things work. When the smoke gets out, it stops! |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Can I borrow the knitting needles again dear ? I need another 64 bytes of memory for a really really long program.  Cheers, Tony. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9751 |
As I said - thing of beauty....  Smoke makes things work. When the smoke gets out, it stops! |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3466 |
Yes, I remember patching punched tape. I got to where I could read the tape, and in some instances could make a correction by punching an additional hole or two instead of splicing in the correction or copying the entire tape, making the necessary corrections. Anybody else re-wire a card sorter? I've forgotten why I had to do it. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| BrianP Senior Member  Joined: 30/03/2017 Location: AustraliaPosts: 292 |
Jeez we're an old bunch!  Really lovely memories... B |
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