I picked this up from the Dayton Hamvention
TC
Posts: 1,019
Hello all,
I went to the Dayton Hamvention yesterday. It was the first time in my 36 years being on this earth that I have ever been to any form of electronic convention. I have to say, " I thought it was awesome". I personally don't understand the HAM thing, but that is not the point. The thing I do believe is, if it was not for HAM operators we would not have the electronic hobby we have today. And I respect that, and I offer my thanks to any and all HAM operators.
But that is not the point of this post.
I was looking around at the flea-market, taking in all the cool stuff, and admiring the vintage electronics. Then I seen a tent that had "Home of the $1 per pound" sign. I figured, couldn't hurt. That is when I seen this
.After a little haggling, I picked it up for $10.
I got it home, and powered it up, it says "self test - ok". But that is it. The buttons do not work at all. I was thinking of taking it apart and trying to find out why. I found a Web site that has the manual, and the repair manual.
But I figure I would ask, Does anyone have any experience with this?
Thanks
TC
I went to the Dayton Hamvention yesterday. It was the first time in my 36 years being on this earth that I have ever been to any form of electronic convention. I have to say, " I thought it was awesome". I personally don't understand the HAM thing, but that is not the point. The thing I do believe is, if it was not for HAM operators we would not have the electronic hobby we have today. And I respect that, and I offer my thanks to any and all HAM operators.
But that is not the point of this post.
I was looking around at the flea-market, taking in all the cool stuff, and admiring the vintage electronics. Then I seen a tent that had "Home of the $1 per pound" sign. I figured, couldn't hurt. That is when I seen this
I got it home, and powered it up, it says "self test - ok". But that is it. The buttons do not work at all. I was thinking of taking it apart and trying to find out why. I found a Web site that has the manual, and the repair manual.
But I figure I would ask, Does anyone have any experience with this?
Thanks
TC
Comments
No idea what's in them or how you might fix one.
Interesting fault. Seems, logically enough, that the internal self-test cannot tell if anyone is pressing the keys so it will pass even when they don't work.
If you are lucky it just a simple fault in the keypad matrix scanning. Perhaps a capacitor gone bad in a power supply some place.
I hope it is just dirt, water residue, or worn out contacts. Past that, I am going to have to read over the schematic to see whats going on.
I'm not sure what you base that on, but we'll leave that go.
Anyway.
Do you have any idea what this contraption is?
Why did you buy it?
I would eevblog mailbag that. Even if you have a compatible EPROM laying around the Propeller would hella easier to work with.
Thank you for the advice, I will be doing that. But sadly I don't have a way to check AC ripple.
Would dawn be a mild dish soap?
That is my understanding. From what I can tell a majority of HAM operators were in the service at one point. Now I am talking about when the semiconductor was just a thought, and tubes were the high tech thing. It was those guys that helped start the electronic hobby we have today.
I mean no disrespect, but does it matter? I have always liked vintage digital electronics. I knew one of two things would happen with it when I got it. 1, repair it, then use it to get a better understanding on logic systems. or 2, could not be repaired and it becomes parts for other projects.
And yes I do have a basic idea what it is, and what it was when I seen it. It is a tool that is used to program(use the term loosely) logic parts. EPROMs, PLA's, etc... I would assume the next question to me would be "Di you know how to use it?" And I would say "I have no idea how to use it, how to program with it, or what parts it works with. But that is just the journey of learning.
I was surprised I could find the manual too, but then I found the service manual with a full schematic.
Could you imagine the shipping to Australia
I do agree with you, the prop would be easier, but this will allow me to understand more things.
Your understanding is correct. It's not just that the HAMS started a hobby. They spurred on the growth of the entire industry. They inspired generations to learn electronics and hence make the progress we have seen possible.
It is well know that a lot of progress in electronics has been initiated by amateurs going right back to the early days of tubes, mostly radio related in those times.
Back in the depths of time if you wanted a radio your probably could not afford to buy one even if it was available. Amateurs designed sets that people could build for themselves. And they did in droves. That's how my father got into electronics as a young lad in the 1930s.
Later if you wanted a television after the second world war the same happened again.
Later in the early 1970's if you wanted a crystal controlled digital clock, for example, you had to build it yourself. Coincidently it was at an amateur radio club meeting that I first learned of digital electronics and the new fangled 7400 logic chips that enabled me to build my first digital clock.
A bit later it was personal computers. The first of them being build by amateur tinkerers.
Today perhaps it's the 3D printer scene that has been propelled forward by enthusiastic amateurs.
It's "HAMS" through out history.
It would be a shame to gut that "contraption" for spares. It's an iconic part of electronics and computing history. When I first ever programmed a microprocessor it was with one of those. And nothing else. We had no computers to run compilers or assemblers on. No, design your code on paper. Assemble it to HEX by hand, enter it into the Data I/O and program an EPROM.
I understand where you're coming from, get an EPROM and test it out.
And that is exactly what I was referring to on my first post. That is why I respect them, and thank them.
I did not want to gut it. That was going to be the last resort, of course after I would get advice from people here.
How would you Assemble it by hand?
I have a few, but I have to fix the buttons first.
Oh?
I asked two questions.
I don't get the attitude.
Anything you wanted to talk about?
You get the programmers instruction reference, which usually is on the datasheet. That document contains the list of CPU instructions and their functions, arguments, addressing modes, etc...
From there, you think about your program, then you write out the instructions you need for it, then you simulate that by walking through your instructions mentally, checking with pencil and paper and the datasheet. Once you've got it mostly sorted, you go instruction by instruction, writing down the hex code for the opcode, then encoding the operands. For relative branches and such, you compute your branch offsets, and at the end of it all, you get a hand listing much like you see from an assembler.
DAT test_program { Program Origin $6000 zero = $30 nine = $39 screen = $7bff numbers = $7cc7 lda #zero 'get zero digit loaded ldx #8 'we are gonna do nine digits digits sta numbers, x 'put them on screen, right to left dex 'next digit? cpx #0 'done ? bne digits 'no, continue writing digits to screen! 'yes, move on to counting on them.... } byte byte $a9, $30 ' lda #zero byte byte $a2, $08 ' ldx #8 byte byte $9d, $c7, $7c 'digits sta numbers, x (check endian on this one) byte byte $ca ' dex byte byte $e0, $00 ' cpx #0 byte byte $d0, $f8 ' bne digits (check branch offset)That's one I did for a test here some time ago. Basically, you just do everything an assembler would do, and then type the hex digits in, one by one...
I've attached a page from the datasheeet, just as a point of reference. Typically, there is some more info about addressing modes and various instruction details too.
I am sorry if it sounded like I had an attitude, I did not. I tried to make it sound like I did not have an attitude, but that was the best I could come up with. Again I am sorry.
You asked
And I still have to respond "Does it matter(happy thoughts while saying it
There was other things I wanted, a old commodore computer (could not see the model number), a Texas instruments computer with internal OS, And an autoclave for sterilizing stuff (that would've been reflow oven V2). But I had to choose the programer because of price. I wanted some left over to be able to get some parts (LED's, caps, etc..)
It was in no way, shape, or form that I wanted to portray an attitude. And I am so sorry it did.
Holy Cow!!! I now have even a larger respect for the old programers. We have it easy today. I don't know if I could do it like that. I have trouble visualizing what the code is doing.
And those logic programmers or EPROM burners didn't check your program either. All they could do is take the hex codes you entered and write them to the chip. It was all up to you to get it right and enter it right. When you were done, you hit the BURN or PROGRAM button an waited as your chip was programmed. Then, take that over to your device, plug it in, turn it on and hope for the best. Sometimes it worked, other times, not so much. Maybe even a blank screen or no function at all. Just one hex code wrong and you're whole program is shot. So you pull out the chip, put it under the UV light as you go back to your notebook and try to figure out what went wrong. Programs were written in tiny pieces just to get parts working. Those pieces got placed in fixed locations as the program grew around them. This led to messy code until you had to clean it up to free up more space in the chip.
I wrote an entire traffic signal light controller this way and it was no easy task. But you sure do get an understanding of the underlying instruction set. I had all the op-codes memorized by the time it was done. Later I wrote an assembler on an early PC just to make the conversion-to-hex step error free. Computing branches is often where mistakes are made as you have to count over both the instructions and operands. NOPs (no operations) were used for padding so minor changes could be made without a wholesale change to the program.
If you ever get it working, take a step back in time and write a little program like potatohead's example. It will give you a real sense of the luxury we now take for granted.
Great fun!
I really want to, I think it would be a great learning experience.
Exactly!! What would've been your reason to buy it? Mine was to learn.
Easy, let's say you are using a Propeller and you have written some PASM code for it.
loop: mov x, #1 mov y, #2 add x, y jmp #loopOf course you have written that out on paper with a pen. Better still use a pecil as it's easier to rub out mistakes and rework it. Yes, you are not allowed an editor. Back in the day getting time on the mainframe to do this kind of editing was impossible.Now you have to turn that into binary instructions.
Let's start with the first instruction. In the Propeller manual we see that "mov" is a thirty two bit instruction with some fields in it.
The first field is the instructions operation code for "mov". It is 101000 so write that down:
101000
Next field is 4 bits, ZCRI, indicating if the zero flag should be changed, or the carry. If the result written and if the required addressing mode. The description of "mov" in the manual says we should set the Z=0, C=0, R=1 so write that down following the bits we had above, use the correct value of I:
101000 0011
Next field is CON that sets the conditional execution. We want this to execute always so 1111 will do it. Add that to the growing instruction:
101000 0011 1111
Next field is the destination address. In our case the address of x. We will know that as we have allocated some location to hold x. So turn that number to binary and add it to what we have:
101000 0011 1111 101000000
Next field is the source operand. In our case the immediate value of 1. So add that to the binary we already have:
101000 0011 1111 101000000 000000000
There we are done. We need that in HEX for the Data I/O or whatever programmer so let's do that conversion. First pack all the bits together:
10100000111111101000000000000000
Now split them into groups of 4 bits:
1010 0000 1111 1110 1000 0000 0000 0000
And rewrite as HEX bytes:
A0 FE 80 00
And there we have it. Repeat for all the rest of your program. Then check it over two or three times.
Enter it into your Data I/O, blow it into your ROM (EEPROM for the Propeller) and see if it runs.
Now, when you are doing this kind of thing, one of the first things you are going to do is write a little monitor program for your Propeller that drives a keyboard and display and will allow you to enter HEX codes directly into memory and then run them. This saves all that EEPROM blowing and you can test out code faster.
Then you are going to want the machine to do all that binary instruction manipulation for you and start to program some simple assembler into it. That would let you write "mov 123, #10" and have all the bits calculated and entered into memory automatically.
Slowly that grows into a proper symbolic assembler and so on and so on until you have written a high level language compiler like Spin.
And that is how we got to where we are today.
I said it before, and I will say it again. Holy Cow!! that is insane!!
I think it is sad that I have never seen any information (paper, documentary, etc...) on how programing has grown to what it is today.
It sounded like it.
(I have that machine (clone) too and it's actually quite fast to program when you get the hang of it. It helps to be able to translate octal to and from binary in your head. If you can already do that with hex then octal is easy of course.)
-Tor
Thats really cool, thanks for sharing.
I used to be able to write quite reasonable programs without the need to refer to the manual for the opcodes. And I wasn't the only one!!!
In fact it was a requirement for maintenance engineers on the mini I repaired and programmed
It get's worse...
You see we only had the chips, Motorola 6809 in this case, no compiler or assembler for them not even a dev board. First we had to build that. CPU, RAM, ROM, UARTs, Timers etc all wire wrapped by hand.
Yes, I remember wire wrapping many boards in the 70s
The 6800 was my firstmicro. Bought a Motorola D1 kit on release - 1976.
I wrote my own cross compiler on a System Ten mini-computer (mini was thelength of my garage).
Those were the days!
I remember a bug that took days to fix. I cheated on my cross compiler and made labels begin with chars G-Z. Immediates began with 0-9 and A-F (not $). Well I forgot once and coded a jump to label BCC to calculate the block check char (a simple CRC) but of course my compiler presumed $BCC. I just could not find the bug in my program. Took me days to realise it was not the program,but my compiler!
BTW That is the mini I could program directly in raw hex (actually 6bit ASCII). Still could today without manuals - that instruction set is burned indellibly into my brain.
Disks were 10MB removable 6x 19" platters worth ~$400 ea. The drives were the size of a washing machine and cost $16,000 ea. And on each course I taught, we pulled the drive to pieces and rebuilt it back up, performing all the alignment checks, including re-aligning all the heads on a special CE disc pack worth $30,000 - any write to the disc would destroy it. BTW each drive used on the course was brand new and afterwards was sold to a customer. Lucky the customer didn't know
Certainly some fun days. I bought my own second hand mini in 1977 - installed in my own garage - sealed and air conditioned. As they say, started my company in the garage and kitchen table
I took it apart, and I was surprised that the boards(4 of them) looked brand new. No dirt, dust, water, nothing. So I checked the buttons, using my meter I could not find any problems with the buttons. So I plugged the boards back together. Turned it back on to see if I could probe the button traces, and the VFD would not come on. I took a closer look, and seen I plugged one plug in wrong. It was the +5V for all the logic, that had nothing on it now. Great!! Had it for a couple days and I broke it.
I spent about 30 minutes tracking down why I had no +5V. Found out I blew a 10A fuse that I first thought was a resistor. So now I have to wait until I need some parts from DigiKey so I can buy the $0.70 fuse that I blew.
Oh, but there is a fan. A loud one.
I tried that before I took it apart. I tried 7 different EPROMs, and a couple AMD pld's PLA. Still nothing.