(Topic ID: 221615)

Oscilloscopes and Pinball


By oldschoolbob

1 year ago



Topic Stats

  • 49 posts
  • 11 Pinsiders participating
  • Latest reply 1 year ago by barakandl
  • Topic is favorited by 8 Pinsiders

You

Linked Games

No games have been linked to this topic.

    Topic Gallery

    There have been 22 images uploaded to this topic. (View topic image gallery).

    Pages from Dolly Manual Complete-2 (resized).png
    u9 p37 (resized).jpg
    u9 p3 (resized).jpg
    u14 p4 (resized).jpg
    u12 p3 (resized).jpg
    cpu 12 (resized).jpg
    cpu 11 (resized).jpg
    cpu 10 (resized).jpg
    cpu 9 (resized).jpg
    pic_24_7a (resized).jpg
    pic_24_6a (resized).jpg
    pic_24_5a (resized).jpg
    pic_24_4a (resized).jpg
    pic_24_2a (resized).jpg
    pic_24_1a (resized).jpg
    a0a (resized).jpg

    #1 1 year ago

    I just got a new oscilloscope. I don’t think I really need it and I don’t really know how to use it but I find them fascinating and want to learn more.
    I have an old MPU 100 that I rebuilt a while back. It boots up on the bench, it boots up in a game and plays fine so I thought I’d try some tests to learn something.

    I started my testing on the CPU (U9). D0 – D7 (pins 33 – 26). The wave forms looked about what I expected.

    d0a (resized).jpg

    Then I looked at A0 – A14 (pins 9 – 24). Again the wave forms looked pretty expected.

    a0a (resized).jpg

    Except A3 and A7 don’t show any dips like the other wave forms.

    a3a (resized).jpg

    Also A4, A8, A11, A13 and A14 all show garbage.

    a4a (resized).jpg

    And the voltage looks way down – 200 MV.

    Why are there no dips in the A3 or A7?

    Why do I get low signal on A4, A8, A11, A13 and A14?

    Is there anything else I might want to look at to learn something?

    Thanks

    (Student) Bob

    #2 1 year ago

    Is this during attract mode?

    #3 1 year ago

    These measurements were taken on the bench after 6 flashes. Would the seventh flash make a difference?

    Bob

    #4 1 year ago
    Quoted from oldschoolbob:

    These measurements were taken on the bench after 6 flashes. Would the seventh flash make a difference?
    Bob

    I think it just sits in a loop if a test fails, but I'd have to check the code to be sure. I could see it never hitting certain addresses in an infinite loop.

    #5 1 year ago

    In order to reduce overall chip count, creative things were done with the memory map / addressing. Sometime, an address line was used only to select PIAs etc. Therefore, while you may see what look like normal waveforms on most of the address lines, others may look totally dead if your scope can't catch and display a single fast change (a single read or write to a port).

    And, as others stated, while in a repeating loop, the code may not cause lower address lines to change until it jumps outside the loop.

    #6 1 year ago

    Interesting discussion. A few things to add/reiterate:

    (1) I think for at least some platforms (Data East I think), there may be custom unofficial test ROMs that cycle more predictably through the address lines. At least with the Data East MPU, the ROMs sit in the upper 48K which should be safe to traverse and still excercise all 16 address lines.

    (2) Because of the nature of memory-mapped I/O, you would want to be careful if you wrote your own code to cycle address / data lines. Depending on the circuit design, a lot of memory-mapped I/O is read/write line agnostic and treats reads and writes identically. The danger is energizing a coil accidentally and not turning it off in time. You'd also have to make sure you tickled the watchdog circuit often enough.

    #7 1 year ago

    Would being in attract mode make a difference? I have a transformer that I often use to get the seventh flash. If I connected that and did the bench test would that be the same as attract mode? Would that get me out of the failed test and out of the loop?

    Quoted from CactusJack:

    Therefore, while you may see what look like normal waveforms on most of the address lines, others may look totally dead if your scope can't catch and display a single fast change (a single read or write to a port).

    My scope has single sequence - Would that help to catch a fast change?

    Most of this stuff is way over my head. I'm not an electrical engineer or a computer programer but I find this stuff very interesting. One thing I've learned is that I need to learn a lot more.

    Thanks

    Bob

    #8 1 year ago
    Quoted from oldschoolbob:

    Would being in attract mode make a difference? I have a transformer that I often use to get the seventh flash. If I connected that and did the bench test would that be the same as attract mode? Would that get me out of the failed test and out of the loop?

    Yes, that would help. At that point it should be in attract mode, even if it's not visible, flashing all the lights and doing different reads from the rom.

    Also, what roms are you using?

    #9 1 year ago

    Hey oldschoolbob, interesting thread! You inspired me to crank up my old oscilloscope (Tektronix 5440) and mess around with it. I don't have a passive probe so I kinda had to wing it to make sure the oscope works. It does! So, now I'm trying to figure out how to get my hands on a probe. Looking to buy or build a P6028 probe. A few old ones out there on ebay, but I am also reading that you can make one. BNC connector, 1Mohm, 24pF. Spec sheet says it is 33mhz, x1, 600v passive. I found a couple of videos on making your own probe and it looks not too difficult. Anyone have suggestions on how I can get this done? (need resistors, etc.)
    Thanks!
    (Don't mean to hijack your thread but I'm eager to learn about oscopes as well.)

    #11 1 year ago

    I would get one if I could find one at 33mhz specification. I have not found one of them yet. And from what I read at Tektronix, they are not interchangeable.

    #12 1 year ago
    Quoted from Enaud:

    I would get one if I could find one at 33mhz specification. I have not found one of them yet. And from what I read at Tektronix, they are not interchangeable.

    I could obviously be wrong but I would expect that the 100MHz will work just fine.

    Every few of my scopes were rated at 100Mhz and I have always purchased 100's as replacements.

    #13 1 year ago

    Wow! That P6028 is kind of old (1963-1966). I don't see any sign of a cap on the manual. Many probes you buy today have a trim cap at the base so you can fine tune the probe to the scope (scopes often have a square wave output for this purpose).

    I wonder how old my Dad's Vacuum Tube 1MHz Tektronix is I have under my bench? Talk about boat anchors!

    #14 1 year ago
    Quoted from oldschoolbob:

    I just got a new oscilloscope. I don’t think I really need it and I don’t really know how to use it but I find them fascinating and want to learn more.

    I don't have any tech info to add but I love that statement! Some people would just look at an o-scope and say "nope" but not you, nicely done

    #15 1 year ago

    They made for a fine opening for the original B/W The Outer Limits!

    In High School Physics, the Teacher got the use of an O-Scope and Played through the entire song of Free Bird one day for us to "Watch". I guess it was his way of trying to somehow make the class more interesting (late 70's). Either than, or he was nursing a Hang Over that day.

    #16 1 year ago
    Quoted from snakesnsparklers:

    I don't have any tech info to add but I love that statement! Some people would just look at an o-scope and say "nope" but not you, nicely done

    Was thinking the exact same thing ... some guys just take the plunge Good for you!

    #17 1 year ago
    Quoted from CactusJack:

    I could obviously be wrong but I would expect that the 100MHz will work just fine.
    Every few of my scopes were rated at 100Mhz and I have always purchased 100's as replacements.

    I found an adjustable probe that I think will work for me and the old oscope that may just be older than me!
    https://www.digikey.com/product-detail/en/digilent-inc/460-004/1286-1075-ND/4840870

    Thanks for the input!

    #18 1 year ago

    The ROMs are from a Stern Magic.

    Zacaj, You were right. I finally got a little shop time and connected my transformer for the seventh flash. Seems I’m getting regular wave forms on all the address lines now.

    a0a (resized).jpg

    Even A3 and A7 look more like a wave form.

    a3a (resized).jpg

    Also A4, A8, A11, A13 and A14 are showing 4.8 volts and a regular wave.

    a4a (resized).jpg

    Which brings up another question – Are those wave forms always changing? If they are, then why? I thought the ROMs sent the information to the CPU to play the proper game. Why wouldn’t they just send the information once.

    And for those of you that are just starting to mess with your oscilloscope, Stick with it. Maybe these guys that have the knowledge will teach us all something. I’m 72 years old but still learning every day.

    And a special thanks for all the knowledgeable guys here for taking the time to teach us.

    Bob

    #19 1 year ago

    The CPU doesn't have any storage, it has to read each instruction for the ROM one byte at a time as it runs. Even in a loop it'd be continually reading. You could even write code that writes an infinite loop into ram, jumps to it, and then later on alters the code from an interrupt while the CPU is running it.

    #20 1 year ago

    I understand the CPU has no memory but I thought that’s where the RAM came into play. I guess not.
    So if the ROM keeps sending data to the CPU, is that data changing? I thought every wave form at a certain pin would all be the same. But that doesn’t seem to be the case.

    I experimented today – using only CPU pin 9 (A0) - I took three measurements. Because the wave was jumping around I had to use the RUN/STOP to get a steady measurement. I got three different results. Even the frequency and peak to peak was different.

    pic_24_1a (resized).jpg
    pic_24_2a (resized).jpg
    pic_24_4a (resized).jpg

    Then I thought my method was fraud. Maybe I wasn’t capturing enough wave form. So then I used Single Sequence to capture the wave. (Thinking Single Sequence would capture the beginning of the wave.) Again I get different results.

    pic_24_5a (resized).jpg
    pic_24_6a (resized).jpg
    pic_24_7a (resized).jpg

    Am I doing something wrong? Is there a way to capture the whole wave form?

    Thanks
    Bob

    #21 1 year ago

    I think you're not understanding how all the lines work quote right.

    If you were in an endless loop, maybe you could, but not during normal operation. Each address line is combining to do so many things. The ROM data isn't changing, but it has be be grabbing thousands of bytes from the ROM just to run attract mode, I doubt your scope can record them all.

    I once made test ROM where every single byte was just repeated instructions saying 'jump to this same address', creating infinite loops, so that I could decode the address on the lines with a logic probe and find where the mpu was hanging. Even in that case, the lowest bits of the address lines were still moving though, as the 'BRA' instruction I used was two bytes in size.

    #22 1 year ago

    For that, you can make a NOP test cpu (6800). You lift all data bit lines (D0-D7) on a 6800 chip and tie them high or low to form a data byte of $01 (hexidecimal). 01 is the NOP (no operation) command for a 6800.

    The Cpu resets, goes to address FFFE and pulls the first half of the 16 bit POR jump address. Increments to FFFF and pulls 2nd half. Jumps to $0101 and pulls the first command byte which will be a $01. 01 says do nothing except increment program counter and get next byte. Which will again be 01. Repeats forever. So, you end up with a 16 bit counter as it counts from 0000 to FFFF and rolls over.

    That will give you a steady waveform.

    #23 1 year ago

    WOW, you guys are so far over my head you’re not even a blip on my radar. But bear with me to see if I’m beginning to get the idea. Let’s say the ROM wants to send the word “cat” to the CPU over the A0 line. The first time it sends the letter ‘c’. The next time it sends ‘a’. Then ‘t’. It’s the CPU’s job to put it all together.

    This is why when I watch the wave on the scope it looks like it’s not triggering – just a bunch of waves dashing across. And when I hit the run/stop it is only showing me one of those letters. And when I hit the run/stop again it may be showing me a different letter.

    If it’s sending thousands of letters – then capturing the same wave form twice would be near impossible.

    I understand that it’s not sending letters – just 1’s and 0’s. But I’m trying to put this in terms that I can understand. Am I on the right track?

    There’s no way I’d ever understand how to write the code. I just want to understand how it works. And you guys are very good teachers.

    Thanks

    Bob

    #24 1 year ago
    Quoted from oldschoolbob:

    WOW, you guys are so far over my head you’re not even a blip on my radar. But bear with me to see if I’m beginning to get the idea. Let’s say the ROM wants to send the word “cat” to the CPU over the A0 line. The first time it sends the letter ‘c’. The next time it sends ‘a’. Then ‘t’. It’s the CPU’s job to put it all together.
    This is why when I watch the wave on the scope it looks like it’s not triggering – just a bunch of waves dashing across. And when I hit the run/stop it is only showing me one of those letters. And when I hit the run/stop again it may be showing me a different letter.
    If it’s sending thousands of letters – then capturing the same wave form twice would be near impossible.
    I understand that it’s not sending letters – just 1’s and 0’s. But I’m trying to put this in terms that I can understand. Am I on the right track?
    There’s no way I’d ever understand how to write the code. I just want to understand how it works. And you guys are very good teachers.
    Thanks
    Bob

    Technically, the CPU would request the word 'cat' from the rom via the address lines. The ROM sends it back via the data lines. But yeah, your central point is correct. Too much going on normally to hope to capture it via the scope

    #25 1 year ago

    It really sounds like you need to get an old book from the late 70's about Programming Micro computers.

    It sounds like you are thinking along the lines of a "program" that is running in a higher language. The 6800 is using what is referred to as machine language. The "C" in cat, exists in memory as an ASCII byte. It takes many line of code to go fetch that byte and then transfer it to an external device, usually through some kind of an I/O port. If it needs to go out to a serial device (a single transmission wire), it has to shift it out one "bit" at a time, which would require a loop of code.

    Almost no way to see a fixed pattern with a scope. Read up on signature analyzers to see how a tech would trouble shoot a running circuit. And even then, it requires you lock the program into a know mode or condition so you know what "should" be happening as opposed to what actually is happening.

    A0 through A16 form a 16 bit address word which is used to point to one specific byte in memory. D0 through D7 contain the data byte that is either going to be written or read from that memory location.

    #26 1 year ago

    It'll also be important to understand how binary numbers work - that's essentially how a group of address and data lines represent numbers.

    As we did on one of your previous threads using the oscilloscope, removing the ROMs from these Stern/Bally boards pretty much makes the CPU cycle through every address from lowest to highest address, and this shows the address lines double in frequency as you measure up each address line number. This doubling in frequency will make sense when you understand binary. It can give you some reference as to whether the address lines are working.

    An oscilloscope will let you see fixed frequency generators that produce a repeating waveform - such as the pin 3 output of the 555 timer at U12 (around 320Hz), the Zero Crossing detector at pin 4 of U14 (120Hz), Clock signals on the CPU at pin 3 and pin 37 (not sure if you're oscilloscope is fast enough to read these), etc.
    An oscilloscope can let you see chip outputs that are weak (not fully swinging one way or another when it should).

    It's very useful in audio circuits as you can see what audio waveforms look like on sound boards when you need to diagnose volume issues, noise issues and no sound issues. Something a multimeter and logic probe can't/aren't designed to do.

    #27 1 year ago

    You just answered my next question - what’s the difference in Address lines and Data lines. So, the address lines are requesting information and data lines are the information going to the CPU. So when I was getting garbage wave forms on A4, A8, A11, A13 and A14 (without the seventh flash) it was because the CPU wasn’t requesting data.

    Looking at the schematic I’m guessing the CPU is requesting, receiving, and sending data to the RAMs the same way. If I probe the address lines and data lines on the 6810 and 5101 I should see a similar wave form – correct?

    I think I’ll try that next.

    Then I’ll get into PIA’s.

    And I’ll get into Quench’s post shortly – I see some very interesting experiments in there.

    I don’t know who is following this thread but I find this one of the most fascinating and learning subjects in a long time. I just want to thank all you guys for being such great teachers.

    Bob

    #28 1 year ago

    Data lines can be either way. The R/W pin on the CPU tells whether it's reading or writing. If you write to ram then the CPU sends them, etc. Address lines are always being set by the CPU. If it were to change them while reading, the data being read would change.

    #29 1 year ago

    Looking at a serial stream from a single address line isn't super useful.

    The real secret sauce is finding the chip enable decodes. A PIA for instance has 3 chip enables CS0, CS1 and CS2 which has a line drawn over it.

    A line means active low, no line means active high. So in order to access the PIA the address lines go through some logic to set CS0 and CS1 high, CS2 low and boom! The PIA now accepts I/O.

    This is how any IC is selected on the bus. Anything that's not active goes "tristate" meaning its pins aren't affected (and can't affect) the rest of the bus.

    Depending on how many channels your scope has you can set logic triggers to look for these states. IE, if channel 1 is high and channels 2 and 3 are low then trigger. This would allow you to pause the scope when a PIA access takes place for instance.

    If you lack the channels you can go super dorky and use glue logic to make an edge detector. In the case of the PIA you'd put CS1 and CS0 through an AND gate, CS2 through an inverter, then both of those outputs through another AND gate. This would create a signal that goes high whenever CPU is trying to access PIA. You could use this as an external trigger for the scope and probe signals to see what's happening when the PIA is pinged.

    #30 1 year ago

    Today I looked at the address and data lines on the RAM chips. As I suspected they are similar to the wave forms from the CPU.

    The R/W makes perfect sense. How else would it know if it’s supposed to send or receive data? A very complicated system – and extremely fast. I noticed all the major IC’s (except the ROMs, of course) have a R/W pin. Including the PIAs.

    Please correct me where I’m wrong but the PIAs read and write similar to the CPU – it’s reading the switches, sends the data to the CPU, then the CPU tells the PIA to fire the coil or light a lamp or change the score display.

    If my theory is correct when I probe the PA(0-7) pins on U10 and U11 I should see activity but the PB pins should be blank because nothing is connected. (bench testing). I check those next.

    There’s a lot going on inside the pinball game. I’d hate to think what’s going on inside my computer. And it all happens so fast.

    #31 1 year ago

    That's not the Ben Heck I always see on youtube - great show. I read your post but I need a clear head to make some sense of it all. And I'm too tired tonight. I'll digest it in the morning. Glad to have you comment on this thread.

    For some reason this thread is bringing in a lot of great talent.

    Bob

    #32 1 year ago
    Quoted from oldschoolbob:

    Please correct me where I’m wrong but the PIAs read and write similar to the CPU – it’s reading the switches, sends the data to the CPU, then the CPU tells the PIA to fire the coil or light a lamp or change the score display.

    So R/W pins on the other chips are the inputs the CPU's R/W pin is writing to. The PIA is configured internally by the CPU as the whether each PA/B pin is an input or an output, and then the CPU reads and writes to the PIA to access those pins.

    Check out
    https://www.dropbox.com/s/b3irqsneg9s54c9/MC6820.pdf?dl=0 for a good overview of how the pia works

    #33 1 year ago

    PiA has two 8 bit data ports, which can output or input data.

    So if you wanted to use one to drive an 8x8 switch matrix you'd set one to output (to drive columns) and one to input (to read switch rows)

    The CPU would then need to change the column at a certain frequency and then read the result of the rows (one byte at a time) to determine what switch was closed. Thus a complete scan of switches would require 16 accesses to the PIA. (eight writes interlaced with eight reads)

    #34 1 year ago

    Really good topic. I didn't consider owning a scope until now,very interesting stuff here.
    -Mike

    #35 1 year ago
    Quoted from Grizlyrig:

    Really good topic. I didn't consider owning a scope until now,very interesting stuff here.
    -Mike

    For the sort of analysis going on here a logic analyzer would probably be better

    #36 1 year ago

    These work well: https://www.saleae.com/?gclid=CjwKCAjwhevaBRApEiwA7aT535j4nwaTiWniKlFB6iKtHb_jkmWK9RNTkCj3JUNadIhpOQW17H2ZNRoCjz8QAvD_BwE

    and have more bits of resolution than low end oscilloscopes.

    If you're just looking for logic levels an analyzer can be all you need!

    #37 1 year ago

    Thanks for the article on PIAs. I just skimmed it over and can tell it will be very helpful. I'll study it tonight.

    I need just a little help with the basics. I understand frequency, pulse width, rise time and period. I understand minimum voltage, maximum voltage and peak to peak. But what is mean voltage?

    I did some more testing today. I looked at the PA's and PB's on U11. As I expected I got wave forms on the PA's (trying to send data to the displays). I got no wave forms on the PB's (trying to send data to the driver board - no solenoids firing in attract mode)

    Then I looked at U10. I got wave forms on the PA's (trying to send data to the light driver and switch strobes). But what surprised me I'm getting wave forms on the PB's (at a slightly less voltage). The PB's are switch returns. There's no switches connected. Could the wave forms be from the PIA calling for data?

    Bob

    #38 1 year ago

    I always thought logic analyzers were super expensive. But that don't look bad.

    #39 1 year ago
    Quoted from oldschoolbob:

    The PB's are switch returns. There's no switches connected. Could the wave forms be from the PIA calling for data?
    Bob

    I think you are seeing the U10 PA5-PA7 and CB2 port come back through closed dip switches. The CPU reads the dip switches by sending strobes through those PA ports and then reading back the PB ports just like it does when it scans the switch matrix. The return PB ports are in common to both dip switches and normal switch returns, but different PA ports (and CB2) are used for the strobes. PA0-PA4 is normal switch matrix strobes and PA5-PA7+CB2 are the dip switch strobes.

    You will also notice U10 PA ports also handle the lamp driver board and display latching (with the help of u20). So when the dip switch is closed and the PIA is controlling the lamp board and displays those PB will show data like you see. The CPU does not care about those PB ports at this point, so it is just ignored. U10 is very busy in Bally games. Has a hand in lamps, switches, and displays.

    If you read the theory of operation PDF it talks more about the interrupt routines, switch matrix, and dip switches.

    #40 1 year ago

    Now that you say that, I do remember reading somewhere that when diagnosing problems on a MPU you should turn off all dip switches. I guess that's the reason why.

    Would it I see a difference if I turned off all the dip switches?

    #41 1 year ago

    I turned off all the dip switches and re-probed. No difference. You’re right, U10 is a busy place.

    I tested the remaining pins on U10 (pins 18 – 40) and screen captured each one. I read the PIA article several times and compared my captures to the info in the article. All this helped me to better understand what’s going on in a PIA. My goal isn’t to fully understand binary numbers and code but to just get a general road map.

    I did see some interesting frequency’s – D0 was over 1.1 MHz and the IRQ’s were in the Hz.

    Next I think I’ll try some of the experiments that Quench suggested. That should be interesting.

    Bob

    #42 1 year ago
    Quoted from oldschoolbob:

    I turned off all the dip switches and re-probed. No difference. You’re right, U10 is a busy place.
    I tested the remaining pins on U10 (pins 18 – 40) and screen captured each one. I read the PIA article several times and compared my captures to the info in the article. All this helped me to better understand what’s going on in a PIA. My goal isn’t to fully understand binary numbers and code but to just get a general road map.
    I did see some interesting frequency’s – D0 was over 1.1 MHz and the IRQ’s were in the Hz.
    Next I think I’ll try some of the experiments that Quench suggested. That should be interesting.
    Bob

    Irqs are being generated by the 120hz zero crossing detector and the 555 timer for the displays

    #43 1 year ago

    Quench, a quick story about binary – years ago a friend of mine (computer geek) built a binary clock. He forced me to read binary because it was the only clock in his workshop. With some thinking (and maybe pencil and paper) I can read some binary.

    I removed the ROMs and started checking the CPU address lines (A0 – A14).

    A0

    cpu 9 (resized).jpg

    A1

    cpu 10 (resized).jpg

    A2

    cpu 11 (resized).jpg

    A3

    cpu 12 (resized).jpg

    At first I didn’t think it was working – then I noticed the frequency wasn’t doubling but it was half-ing (each frequency was half the one before). Don’t know why mine is counting backwards.

    Then I checked the 555 pin 3. It’s close – 305.2 Hz.

    u12 p3 (resized).jpg

    The zero crossing was spot on.

    u14 p4 (resized).jpg

    This new oscilloscope didn’t have any problems reading the CPU clock signals

    Pin 3

    u9 p3 (resized).jpg

    Pin 37

    u9 p37 (resized).jpg

    I may be looking for your help soon on a sound card. I just started working on a Stern Lectronamo that needs a lot of work – including no sound.

    This has been a very educational and enjoyable few days. I know I’ve learned a lot. I want to thank everyone for their suggestions, comments and mostly their knowledge.

    Thanks

    Bob

    #44 1 year ago

    And you realize this is what you are looking at:

    Address line:
    76543210

    00000000
    00000001
    00000010
    00000011
    00000100
    00000101
    00000110
    00000111
    00001000

    #45 1 year ago
    Quoted from oldschoolbob:

    I may be looking for your help soon on a sound card. I just started working on a Stern Lectronamo that needs a lot of work – including no sound.

    http://www.techdose.com/projects/Stern-Pinball-SB100-Sound-Board/346/page1.html. Mostly just need to find where the signals are disappearing

    #46 1 year ago
    Quoted from CactusJack:

    00000000
    00000001
    00000010
    00000011
    00000100
    00000101
    00000110
    00000111
    00001000

    0
    1
    2
    3
    4
    5
    6
    7
    8

    not sure about address line

    #47 1 year ago

    Thanks Zac, I think I have that in my file already. But I need to get a bunch of other stuff going first. I know I have power problems then connectors. It's really tired electronically.

    Bob

    #48 1 year ago
    Quoted from oldschoolbob:

    At first I didn’t think it was working – then I noticed the frequency wasn’t doubling but it was half-ing (each frequency was half the one before). Don’t know why mine is counting backwards.

    Arghh, sorry had my wires crossed there, yes as you go up address line number the frequency will halve the previous line.

    Quoted from oldschoolbob:

    I may be looking for your help soon on a sound card. I just started working on a Stern Lectronamo that needs a lot of work – including no sound.

    No problem - there's probably lots of useful stuff in that Magic sound board thread we worked on nearly a year ago:
    https://pinside.com/pinball/forum/topic/stern-magic-no-sound
    .
    .
    Coming back to binary, the MPU board communicates with the solenoid driver board for momentary solenoids in 4 bits. It also communicates the "number to display" (BCD binary coded decimal) to the displays. And also 4 bits to the lamp driver board decoder chips.
    These groups of bits come from the PIA chips output on the MPU board.

    Below are 4 binary bits on the left. Grouped together they can represent 16 different numbers based on their logic levels - a 0 is Lo, 1 is Hi: Can you see the pattern in the binary numbering? For every binary bit you add to the left, you double the amount of numbers that can be represented. 8 bits are usually referred to as a 'byte' and can represent one of 256 different numbers.

    BIT
    3210
    0000 = 0
    0001 = 1
    0010 = 2
    0011 = 3
    0100 = 4
    0101 = 5
    0110 = 6
    0111 = 7
    1000 = 8
    1001 = 9
    1010 = 10
    1011 = 11
    1100 = 12
    1101 = 13
    1110 = 14
    1111 = 15

    Understanding these can help you pinpoint communication issues between the MPU board and the peripheral boards.

    #49 1 year ago

    Pages from Dolly Manual Complete-2 (resized).png

    Promoted items from the Pinside Marketplace
    $ 229.99
    Lighting - Other
    Lighted Pinball Mods
    $ 25.00
    Cabinet - Other
    Filament Printing
    $ 1,099.00
    Flipper Parts
    Mircoplayfields
    € 3.70
    £ 20.00
    $ 4.49
    Electronics
    Yorktown Arcade Supply
    From: $ 99.99
    Cabinet - Other
    Lighted Pinball Mods
    From: $ 9.99
    Eproms
    Matt's Basement Arcade
    $ 5,799.00
    Pinball Machine
    Flip N Out Pinball
    $ 66.95
    Cabinet - Shooter Rods
    Super Skill Shot Shop
    $ 18.99
    Eproms
    Matt's Basement Arcade
    From: $ 200.00
    Playfield - Toys/Add-ons
    Williamson Pinball Mods
    $ 999.00
    $ 5,899.00
    Pinball Machine
    Classic Game Rooms
    $ 750.00
    Flipper Parts
    Mircoplayfields
    $ 59.99
    Hardware
    Chroma Pinball
    $ 9.99
    Eproms
    Matt's Basement Arcade
    $ 79.99
    Cabinet - Armor And Blades
    PinGraffix Pinside Shop
    $ 400.00
    Playfields
    Maple Street Sign Shop
    $ 66.95
    Cabinet - Shooter Rods
    Super Skill Shot Shop
    $ 25.00
    Cabinet - Other
    Filament Printing
    $ 229.99
    Lighting - Other
    Lighted Pinball Mods

    Hey there! Got a moment?

    Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside