# Tales from the S-100 dark side.



## jcdammeyer (Apr 12, 2022)

It's been too wet to cast aluminum.  Waiting for needle bearings from China for the harmonic drive project.  Haven't decided what to do with the power drawbar project.  So no machining for a while.  What to do......
Well I've been meaning to clean up some of the old S-100 computers that have been collecting dust for the last 30+ years so I thought I'd pull them out and inventory what I have.  Turns out to be a lot.
Found an S-100 facebook group and have had some nice conversations and help.  
At this point I've now been able to get a Hydra 80186 CP/M-86 up and running.  Has 5.25" floppy and hard drive.
Next was the Ithica Intersystem Z80 system with two 8" floppy drives.  What is amazing is all the floppies are readable so far.
Current reforming the power supply capacitors on the third system which has a M68000 with CP/M-68K.  The capacitors in it are pretty poor.  Way more than two hours per cap to reform them.  Going to be a while yet before I can see if it boots.
Another system that was taken apart, cabinet scrapped for the metal used to have two 8" floppy drives that were also scrapped.  It's a Tecmar 8086 with 256K memory and it ran MP/M-86 for a multi-user system.  I think I trashed the hard drives on that one.  So all I have left are the boards.
And finally my own personal Z80 system that had a dual Persci drive.  The heads were moved by a voice coil system instead of stepper motors.  I may plug all those boards into a motherboard (I have extras) and see if I can make it work.  Just for fun.
What's interesting too is the tools for these systems.  I have COBOL, FORTRAN, FORTH, PASCAL, DBASE-II, Plotting programs and of course the Adventure Game.


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## Dabbler (Apr 13, 2022)

what, no FOCAL?   Back in '74 FOCAL was all the rage - I even helped port a copy from a PDP-8 to an Intel 4004 system.

-- I have very little hardware left that is older than a few years.  (I'm a little envious)

the only program I got to write (in FOCAL) was a version of Mastermind (the colour matching peg game)

Before I hit U of Waterloo, most of my programming was in FORTRAN or machine code...


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## jcdammeyer (Apr 13, 2022)

Dabbler said:


> what, no FOCAL?   Back in '74 FOCAL was all the rage - I even helped port a copy from a PDP-8 to an Intel 4004 system.
> 
> -- I have very little hardware left that is older than a few years.  (I'm a little envious)
> 
> the only program I got to write was a version of Mastermind (the colour matching peg game)


The big language, other than TRS-80 and Microsoft Basic was Pascal.  Ithica had PascalZ and Turbo Pascal was $49 which included the book that I still have.   Borland's Turbo eventually became Delphi with Object Oriented Programming.  It's still around in RAD studio although they've drifted towards C and Python.  
Delphi OOP Pascal Programs


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## Dabbler (Apr 13, 2022)

I didn't see PASCAL until around 1977.  By then I had used BCPL and C enough to stay away.


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## jcdammeyer (Apr 13, 2022)

Dabbler said:


> I didn't see PASCAL until around 1977.  By then I had used BCPL and C enough to stay away.


Wirth's book on Pascal is dated 1975, Kernigan and Richie C is 1978.  But it was the dominant language in Unix systems so I used it in a 500 series Comp Sci graphics course on a PDP-10.  But the year before we'd used UBC PASCAL for a telecom course along with a number of other languages.  
After Uni I discovered ICON in a book store in San Fransisco.  Now that was a cool language and Python now has a lot of what was in it.

What I've found now is that the worst languages have the least amount of documentation with the programmers thinking the languages are self documenting.  Really just an excuse for not doing the hard part which is explaining why rather than how.  Python is the worst for that. But let's not go there.

Here's the Hydra 80186.  All on one board with a big cable going to a DTC-520A hard and floppy controller.   Runs CP/M-86.  Nice little machine.  Of course a Pi or Beagle runs circles around it.






Next we have the Z80 system.  Thse are the two 8" floppy drives.





And inside the processor box are a lot of RAM cards.  Why if the Z80 only has 64K memory address-ability?  Well there's a paging system on the CPU board that lets it use at least 512K in 4K pages.  Shades of IBM 360 architecture.  Anyway each track on the floppy is buffered so once it's read into ram it stays there so reading files is slow the first time and after that pretty quick.





Finally we get the M68000 16 bit computer that can linearly address 16MB.  A 256K ram card and a 64K are in there along with the 8 serial port card, and CPU,  and disk controller card.


and big heavy power supply and box for a 5.25" floppy and hard disk. Overkill. The front panel for the Integrand disk box has gone missing...


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## jcdammeyer (Apr 20, 2022)

Aaaargghhh.  I have three different power supplies that used to work with the older 8" drives.  One, a Power-One CP272 is supposed to supply 24V, 8V, -5V and +5V.  The 24V is fine but the 5V can't even provide 1A and it's rated fro 2.2A.  So the 8" drive won't work with that.

Another supply I built years ago is 2.5A at 24V and 1A at 5V.  No problem with 5V but as the regulator gets warm the 23.8V drops to 17V.  

The other supply which should be able to run the hard drives is friggen huge and meant for a 20 slot motherboard in addition to two 8" floppies and a hard drive.

So I buckled and ordered this for delivery on Sunday.  https://www.amazon.ca/gp/product/B07RT54H9V/ 

BTW, if anyone is cleaning out a closet and stumbles onto a 5.25" floppy drive or/and a 5.25" older style hard drive with the two cables I'm interested.  If it's really cheap.  Like shipping costs...

Thanks
John


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## Canadium (Apr 21, 2022)

jcdammeyer said:


> Aaaargghhh.  I have three different power supplies that used to work with the older 8" drives.  One, a Power-One CP272 is supposed to supply 24V, 8V, -5V and +5V.  The 24V is fine but the 5V can't even provide 1A and it's rated fro 2.2A.  So the 8" drive won't work with that.
> 
> Another supply I built years ago is 2.5A at 24V and 1A at 5V.  No problem with 5V but as the regulator gets warm the 23.8V drops to 17V.
> 
> ...



I'm pretty sure I have a floppy drive in an old computer I have kicking around. If I can manage to remove it you are welcome to have it for shipping cost. I'm guessing your power supply problems are nothing more than a blown electrolytic capacitor. Not too hard to replace. When they go the tops usually bulge out so they are quite easily identifiable and replacements are usually pretty cheap. Just a bit fussy to replace. You need a good soldering iron for electronics.


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## Dabbler (Apr 21, 2022)

I think I recycled both my 5 1/4 and 8 inch drives a few years ago... shame...


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## jcdammeyer (Apr 21, 2022)

Well the MPC 8" half height drive has some issues which explains why the Ready signal never shows up.  A scope on the optical sensor that detects the index hole shows no activity.  A meter set to diode mode sees a 1V drop across the double sided sensor but open circuit on the single side sensor.  So I'm guessing the diode is toast or over time vibration has mucked up the diode which of course is glued into the frame.  Or the wire is broken inside.

Second:  the home slotted sensor has a broken wire where it snapped off the top.  I might be able to fix that by carving away some of the plastic to get access to more of the wire.  Don't want to unscrew it if I don't have to because then I have to go through the alignment process.

Guess I should have done those tests before I splurged $32 on the power supply.


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## jcdammeyer (Apr 21, 2022)

Dabbler said:


> I think I recycled both my 5 1/4 and 8 inch drives a few years ago... shame...


Yeah, I did the same about 5 or 10 years ago.  Not only that, some of the CPM system disks, the manuals and the OS9-68K system disks and manuals.  Silly me.


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## jcdammeyer (Apr 21, 2022)

Canadium said:


> I'm pretty sure I have a floppy drive in an old computer I have kicking around. If I can manage to remove it you are welcome to have it for shipping cost. I'm guessing your power supply problems are nothing more than a blown electrolytic capacitor. Not too hard to replace. When they go the tops usually bulge out so they are quite easily identifiable and replacements are usually pretty cheap. Just a bit fussy to replace. You need a good soldering iron for electronics.


Thanks.  Hold off until I get further along into this.


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## Dabbler (Apr 21, 2022)

jcdammeyer said:


> AI did the same ... Not only that, some of the CPM system disks, the manuals and the OS9-68K


OS9 68K rocked.  I only got to use it for a year or so, but I like it a lot.  Pity.


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## jcdammeyer (Apr 21, 2022)

Dabbler said:


> OS9 68K rocked.  I only got to use it for a year or so, but I like it a lot.  Pity.


I used it for two years in The Netherlands at a company that made Trim & Form equipment for bending and trimming the leads on Integrated Circuits.  One of the reasons I got that job was because I'd ported it to a system here in Canada just before we moved.  This was before Linux.  Hard to say if it would be any better.


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## Susquatch (Apr 21, 2022)

jcdammeyer said:


> BTW, if anyone is cleaning out a closet and stumbles onto a 5.25" floppy drive or/and a 5.25" older style hard drive with the two cables I'm interested. If it's really cheap. Like shipping costs...



I am soooooo envious. 

I will see what I have. Most things got put out with the trash in one of my moves. I had a giant S100 rack system. I cried as I took it to the curb to wait for the Hearst. 

I am almost certain I have a few drives of various sizes laying around that you can have. I mostly kept stuff like that for parts (screws, motors, steppers, magnets, etc) I'll look later today or tomorrow. 

I have very much enjoyed reading all the posts on this thread. Waaaaayyyyy too much of my young life represented here. I'm too old to start crying over hardware and software. 

But while everyone is sharing their history, my own specialty was at the hardware/software interface. After the early days of designing and hand building small dedicated systems, etching circuit boards, boot loaders, tape readers, building my own computers, writing my own OS, etc etc along came CPM........ O M G...... Soooooo beautiful! Sooooo Structured! Sooooo Adaptable! So many others out there doing the same things. Assemblers, compilers, etc etc all became possible! 

I started to focus on designing and building boards for specialty purposes - mostly early controllers (not microcontrollers) that were controlled by the OS. That meant writing drivers with time critical functioning. I didn't follow the coder rules so things actually worked......LOL! I recall getting blasted by a larger company for software I wrote that mixed data and code - in particular I modified the code itself according to inputs received. They told me to rewrite it properly, I told them to FO, they wanted their money back, I wanted my code back, they tried to fix it themselves, then folded and let me do it my way. In hindsight I was more stubborn then than now! 

I continued to like that side of things through the advent of the first microcontrollers. I still have a tray of 8748 controllers that I used to do all kinds of things. Some probably still have code in them. As time passed, I also learned to like the Parralax Basic Stamp - talk about a fast development system! 

That's prolly why I can't wait to get cracking on the Arduino. 

But first I need to finish a few major hardware projects...... 

Ya, life is a big circle. Wtf is going on with that fountain of youth thing they are working on? They better hurry up or ill miss out and never get to my Arduino!


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## jcdammeyer (Apr 21, 2022)

My first computer was a National Instruments SC/MP with teletype at work for I/O.  After that S-100 Vector Graphics Z80, Vector Graphics Serial, a kit 8K memory board, Vector graphics Floppy controller board and Persci dual 8" disk drive with voice coil positioning.  I used the monitor that came with the Z80 board to key in hex bytes, into ram to bring in the bios from the CP/M distribution disks.  Modified that to access my console and disk routiines and then inserted a new 8" floppy and performed the write track code for tracks 0 and 1.

After a few attempts which memory has lost as to how many is a few I booted CP/M.   From there the second drive was used to pull in the rest of the .com programs off the Digital Research disk and it was put safely away.  First step after that was to use ed.com to modify the bios in the same way I'd done it manually.  Assembled it with asm.com and was able to create a proper bios hex file that became the system bios.

In looking through my 8" floppies I've found the wordstar document files for several of the courses I took in University.  I was the only one in the non-computing science classes who was using a computer and printer to submit essays.  So long ago.  

The Arduino is pretty simple and has amazing support for all sorts of hardware.  The downside is it doesn't easily let you get under the covers.  So no break points.  No looking at variables or registers.  So if a program that runs great for 17.5 hours suddenly reboots you are 'screwed' essentially because one of the many library routines has decided to lose memory or run a loop until it runs out of memory.

But it's really easy to work with too.  And amazing things can be built with it.


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## Dabbler (Apr 21, 2022)

I came along just a little after:  My first micro was helping wire wrap a 4004 board, but my first design job was a 6800 'fox' generator for teletypes.  I was paid with an ASR33 teletype.  I designed the I/O part of the board and wrote all the software.  This was for a Waterloo company that was still maintaining ASR and KSR teletypes. (in 1975)

I didn't actually own my own computer until a few years later - a used Apple II with one floppy.


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## jcdammeyer (Apr 21, 2022)

So the latest in this saga is why the MPI 41 series 8" disk drive didn't create an index pulse.  There are two sensors and two IR drivers.  One of them had a wiggly lead and it was the one for the standard 8" floppy in the normal position.  And measuring at the connector showed one had a diode drop of 1.3V and the other open circuit.  Had to take a fair amount apart in order to get at it.  Then heat the body with the soldering iron so it was hot enough to melt the glue holding it in.  And the insulation for the black wire just melted and the wire fell off.  Clearly snapped at the body which is why it didn't work.

Now I can read the part number.  It's an extinct TL 31B with 100mA max current and emissions at 980 nm.  I found a replacement for about $9 at Digikey that is now on the way.  Spectral output is at 945 nm.  Hopefully that will be close enough.  The ony 980 nm ones l could find are surface mount devices.  

PART: 1125-1026-ND
MFG : MARKTECH OPTOELECTRONICS / MTE9440N
DESC: EMITTER IR 945NM 100MA TO-18

There are more expensive ones at 950nm but we'll see.


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## Susquatch (Apr 21, 2022)

jcdammeyer said:


> In looking through my 8" floppies I've found the wordstar document files for several of the courses I took in University.



Someplace somewhere I have the source code for an early version of Wordstar when it was last written in assembler before it was rewritten in C. As I recall they were looking for a more efficient way to manage formatting control codes and more efficient data caching on disk. As I recall, they never paid me for the full job because faster processors and bigger faster disks solved their problems for them.

That was back before bloatware was invented. It had to be compact and efficient then because it had to fit in the available memory.


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## Susquatch (Apr 21, 2022)

jcdammeyer said:


> So the latest in this saga is why the MPI 41 series 8" disk drive didn't create an index pulse.  There are two sensors and two IR drivers.  One of them had a wiggly lead and it was the one for the standard 8" floppy in the normal position.  And measuring at the connector showed one had a diode drop of 1.3V and the other open circuit.  Had to take a fair amount apart in order to get at it.  Then heat the body with the soldering iron so it was hot enough to melt the glue holding it in.  And the insulation for the black wire just melted and the wire fell off.  Clearly snapped at the body which is why it didn't work.
> 
> Now I can read the part number.  It's an extinct TL 31B with 100mA max current and emissions at 980 nm.  I found a replacement for about $9 at Digikey that is now on the way.  Spectral output is at 945 nm.  Hopefully that will be close enough.  The ony 980 nm ones l could find are surface mount devices.
> 
> ...




If it doesn't work, I might have something. But I will have to dig for it and might even have to test it. I won't do that unless you need it.

Also, have you considered buying the pair instead?


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## jcdammeyer (Apr 21, 2022)

Susquatch said:


> If it doesn't work, I might have something. But I will have to dig for it and might even have to test it. I won't do that unless you need it.
> 
> Also, have you considered buying the pair instead?


Looking at the curve of the new device it seems like it should be fine.  It's on the way from Digikey so I'll find out next week.  I likely also have some IR diodes in my parts bin but they are fully plastic and I wanted something with roughly the same beam angle too.  We'll see.  I don't want to remove the receiver assembly.  Even if I scribe lines in the casting, which I'd do before I remove it I'd rather not.  And a broken wire on the sender is a pretty big clue to the missing index pulse.


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## jcdammeyer (Apr 21, 2022)

Susquatch said:


> That was back before bloatware was invented. It had to be compact and efficient then because it had to fit in the available memory.


I recall the punch card and a lot of terminals adding up to over 300 users at UofA with disk paging to deal with only 16MB of addressable memory.  Now you can get a Raspberry Pi4 with 8GB of memory.  That's 500 times as much.  But then the FLACC (ALGOL-68) compiler was written in assembler.


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## jcdammeyer (Apr 21, 2022)

Turns out the cathode was the case so I was able to solder on a new thicker wire.  I then built a mold out of tape and plastic and poured in some epoxy.  Tomorrow I'll solder on some slightly more flexible wires and attach them to the existing stiffer ones and then give it a try.  I'd rather make some sort of clip to hold it in place as opposed to the original glue it in place.  Not sure what to do there yet.


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## jcdammeyer (Apr 22, 2022)

Final report on the MPI 8" disk drive repair.  Dug away some plastic on the track zero slotted connector.  Soldered on the broken wire.  Built a dam around it with tape and filled the cavity with epoxy.  Now it's safe from being knocked around.  
Next soldered more flexible red and black wires to the IR LED.  Then heatshrink around each of those.  And then larger diameter heatshrink around both.  Bend at right angles and connect to original wires, now  a bit shorter to deal with the new wires.  Hot melt to hold the sensor and the wires in place.

End result is:

```
D)isk, T)track, S)ector, B)locksize, R)ead, W)rite, V)iew, F)ormat, E)xit -->r

Read command....
Track = 0 Sector = 2 Blocksize = 128
CORRECT? (Y/N)y
Reading disk drive
Disk sector size is -->128

D)isk, T)track, S)ector, B)locksize, R)ead, W)rite, V)iew, F)ormat, E)xit -->v

0000 C3 5C E7 C3 58 E7 7F 00 20 20 20 20 20 20 20 20  >.\..X..        <
0010 20 20 20 20 20 20 20 20 43 4F 50 59 52 49 47 48  >        COPYRIGH<
0020 54 20 28 43 29 20 31 39 37 39 2C 20 44 49 47 49  >T (C) 1979, DIGI<
0030 54 41 4C 20 52 45 53 45 41 52 43 48 20 20 00 00  >TAL RESEARCH  ..<
0040 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  >................<
0050 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  >................<
0060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  >................<
0070 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  >................<
D)isk, T)track, S)ector, B)locksize, R)ead, W)rite, V)iew, F)ormat, E)xit -->
```

Yahoo!  It works again.


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## jcdammeyer (May 28, 2022)

jcdammeyer said:


> Looking at the curve of the new device it seems like it should be fine.  It's on the way from Digikey so I'll find out next week.  I likely also have some IR diodes in my parts bin but they are fully plastic and I wanted something with roughly the same beam angle too.  We'll see.  I don't want to remove the receiver assembly.  Even if I scribe lines in the casting, which I'd do before I remove it I'd rather not.  And a broken wire on the sender is a pretty big clue to the missing index pulse.


Can't believe that was 21APRIL2022.   Went on next to the ERG M68000 S100 system.  Got it going after many contortions to create a boot floppy for OS9-68K.  Next step is to modify the EPROM monitor to test for a floppy and if not there with an OS then boot from the hard drive. 

Meanwhile the parts arrived for the S100 board that interfaces to IDE hard drives or Compact Flash cards.  Still don't have the compact flash card holders but did write a short program to cycle the displays.  Here's a Youtube video.
Testing IDE_CF display.
With this board I can add an IDE hard drive to the dual 8" floppy system that runs CPM-2.2.  Likely will upgrade to CP/M 3 since it works better with larger sectors.  And the board also uses Compact Flash cards so don't even need a noisy disk drive at all for this.  Add a solid state relay to power down the 8" drives and the system would actually be very quiet.


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## Perry (May 28, 2022)

This is a good thread.   Takes me back to 1976 when the Radio Shack catalog came out.   There it was the TRS-80 ..... and I wanted it.  I don't remember the exact price but it was around $2500.  I do remember my dad saying "NO" and that it cost the same amount as my mom's new Dodge Dart.    lol

A few weeks later I talked him into lending me some money.  (I think it was $500)   From this I bought my first  Zilog Z80 chip  (I believe it was close to $150, just for the chip) and started to build my first computer from scratch.   Slow and steady it actually progressed into an assembly driven unit.   (Years later Timex Sinclair came out with a Z80 unit you could build.  I wrote a letter to them and they actually sent me a free eprom that had their BASIC language on it)   This was wired in and worked very well. 

I'm going from memory here but I think the Timex Sinclair had 4k of ram.   I was running 16k of ram.   All programs had to be typed in and power left on or they were gone.  lol.     When the Timex Sinclair started to get more popular I  started to make memory expansion boards for my friends to bring them up to the 16k of ram.     The money I made from this was enough to purchase a TRS-80.

This all happened over a few years, but that first fall day of picking up the Radio Shack catalog is still stuck in my head.    I was in grade six, walking home from school.


The trials and errors of learning in this manner have stuck with me for life.   Best money my father ever invested in my education.


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## jcdammeyer (May 28, 2022)

Perry said:


> The trials and errors of learning in this manner have stuck with me for life.   Best money my father ever invested in my education.


I was 12 when my dad bought me the Heathkit 6 transistor radio.  My first project.  Years later, from a suggestion of a friend I'd met in high school band, I was convinced to start the Electronics-10 program in Grade 11.  So high school took 4 years instead of 3 just to get that third year of Electronics.
From there to CJOI in Wetaskiwin as an evening 'rock jock'.  While there I managed in my off time to figure out that RTL logic was overheating in the control cabinet of their automation machine.  The skills from High School paid off.  From CJOI, to IBM in Edmonton as an OPCE.  (Repair Selectric Typewriters).  That was the time when it was possible on one salary to afford a one bedroom apartment and put a girlfriend through University.
Of course the danger in doing that is that once they graduate they may not stick around.


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## Perry (May 28, 2022)

The real bug started earlier.  My dad had given me a Rocket Crystal radio he had as a kid.   From there I built my own crystal radio.  

Do you remember Radio Shack had the Free Battery of the month club.  I would stop in each month to get my free battery and hound the repair tech that worked in the back.   That poor tech took mercy on me and gave me a brand new Ungar Soldering iron and a Heathkit (for some type of electronic tester.....I don't remember what it was for.)   I read the instructions, learned to follow directions, solder, understand the circuits.    All small steps leading you down a road. 


I also did the electronics program in Grades 9,10,11, and 12.   I was way ahead of the game.  The instructor would let me play in a back room with an amateur radio.   Studied the morse code and wrote my amateur radio license. 

The electronic magazines back in the day always were a good source of learning also.  Lots of cool interesting projects.   I grew up in a small town and that made it harder to obtain a lot of the parts I needed.  Lots of letter writing and waiting.   


I still have that soldering iron today.   If I could only count the things it has repaired, designed and built.


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## jcdammeyer (May 28, 2022)

I have an old Weller WTCP-60 that I still use as the second iron to heat up parts that need to be heated at both ends to come lose.


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## Dabbler (May 28, 2022)

In high school all I could take that was close was Electrical Wiring.  For the final project, most guys built a 3-way (or more advanced students 4-way) light circuits.

I was bored, so I made a 4 digit combination lock, with 5 buttons using 8 or 9 relays.


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## Perry (May 28, 2022)

Dabbler said:


> using 8 or 9 relays.


You're older then you look.....


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## whydontu (May 28, 2022)

Lost my microprocessor virginity to a Netronics ELF II RCA COSMAC 1802 processor with 256 bytes of RAM. Wirewrapped a 1024 byte add-on memory card. Added a Don Lancaster video interface.

Pestered the local Radio Shack until they hired me. Spent all my spare money buying parts and tools from myself.

As the on-staff computer geek at my store, I made our first TRS80 26-1001 micro sale to my older brother.


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## jcdammeyer (May 28, 2022)

Radio Shack was my first job too.


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## Dabbler (May 29, 2022)

@whydontu Another COSMAC guy!  Remember the 'hokey' COSMAC trainer with the 8 toggle switches?  I used that to prototype code for a project at University.  Small world.


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## Dabbler (May 29, 2022)

Perry said:


> You're older then you look.....


Perhaps not quite so old... I salvaged the relays and push buttons from F104 (starfighter) navigation equipment the school had around.  This happened in 1972.


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