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Thread: Reproduction SIM4-01 set?

  1. #11

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    The SIM8 uses the same MP7 board as the SIM4. It would have the same issue. There is no feedback from the MP7 board to say when it is done. The delay loop for the SIM4 would be the wait for the board to finish so the code can change the address and data. It is an open ended control so it only needs to deliver a constant signal while the MP7 sets the right pulse width and dwell between pulses. The 1702 needs more dwell time between shorter pulses and more pulses than the 1702A. It would either have to use a different port pin like the SIM4 or have a switch to select the different dwell signal if using the MP7. I don't know how the MOD8 or MOD4/40 deal with programming as I've not studies either of them that closely. They may both completely control the dwell between pulse and the pulse rate. The SIM4 does not.
    Dwight

  2. #12

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    Quote Originally Posted by Dwight Elvey View Post
    The SIM8 uses the same MP7 board as the SIM4. It would have the same issue. There is no feedback from the MP7 board to say when it is done. The delay loop for the SIM4 would be the wait for the board to finish so the code can change the address and data. It is an open ended control so it only needs to deliver a constant signal while the MP7 sets the right pulse width and dwell between pulses. The 1702 needs more dwell time between shorter pulses and more pulses than the 1702A. It would either have to use a different port pin like the SIM4 or have a switch to select the different dwell signal if using the MP7. I don't know how the MOD8 or MOD4/40 deal with programming as I've not studies either of them that closely. They may both completely control the dwell between pulse and the pulse rate. The SIM4 does not.
    Dwight
    I haven’t found the SIM programmer code online to look through it. My suggestion was that the MIL MOD8 uses the same dual monostable hardware design as the MP7. However, the MIL does not use both pulse generators so it would not surprise me if the SIM didn’t either. The MIL only triggers the shorter one and uses a software loop to determine the duty cycle. They also speed up the overall programming by doing a program-check, program-check loop until the eprom matches and then it does the overprogram. there are many common aspects between the programming hardware between the MIL and the SIM systems, soo.... I would not be at all surprised if the monitor for the sim8 and SIM4 also ignores the dual multivibrator hardware setup, does duty cycle in software, and uses the program-check + overprogram algorithm since that is fastest.

  3. #13

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    i had no idea that the MIL mod-8 board set had been reproduced. The board set is probably not cheap, but where else are you going to go for one?

    As I recall, those boards used first-gen TTL and some of those chips might be getting a bit scarce/pricey particularly in non-LS versions (the -L's might be tricky, for example) if you wanted something period-correct.
    And then, there is the memory-but I've got some gold lid white ceramic 2102's looking for work...this would be very tempting. I've even got a MIL8008 for such a project!

    I really like the MIL monitor. I use it in an emulator (Dunfield's transcription) and it is amazing what they packed into it. I have read somewhere that there is a bug in that transcription; I've never followed up on it. But my ESP8266 emulator hangs up if I dump a certain location and I've run a lot of other real 8008 software including SCELBAL in my emulator OK. Believe me, I've made more than my share of mistakes "digitizing" worn-out ASR-33 teletype output!

  4. #14

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    Slob..

    I wasn’t going for period perfect so i don’t have any idea how much extra that would take in time and cost. There are a dozen boards in the set, I forget how much they cost. I think Charles has some boards available still.

    You are right about the mil monitor, it is very powerful and the symbolic input and symbolic output in the MON80 can’t be beat.

    Craig

  5. #15

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    Quote Originally Posted by candrews View Post
    I haven’t found the SIM programmer code online to look through it. My suggestion was that the MIL MOD8 uses the same dual monostable hardware design as the MP7. However, the MIL does not use both pulse generators so it would not surprise me if the SIM didn’t either. The MIL only triggers the shorter one and uses a software loop to determine the duty cycle. They also speed up the overall programming by doing a program-check, program-check loop until the eprom matches and then it does the overprogram. there are many common aspects between the programming hardware between the MIL and the SIM systems, soo.... I would not be at all surprised if the monitor for the sim8 and SIM4 also ignores the dual multivibrator hardware setup, does duty cycle in software, and uses the program-check + overprogram algorithm since that is fastest.
    OK, you made me look. For the 1702A, the SIM4 only sends one 0.5 second pulse to the MP7 per address. The MP7 generates approximately 100 ea 3 ms pulses with a dwell time of about .25 ms. It does this only once per address totaling 2 minutes. There is no significant delay between addresses.
    For the 1702, the SIM4 only does a 0.05 second pulse for a about 15 ea 3 ms pulses. It does this for each address and then repeats the address/data sequence for 10 passes. The MP7 actually creates the dwell time between the 3 ms pulses but the SIM4 creates no specific delay for each address. Each address gets 10 shorter passes, only for the 1702, non-A.
    Dwight

  6. #16

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    Dwight

    Good information to know, thanks

    This is pretty much what the MIL documentation SAYS its resident monitor does, but it does not. I think MIL lifted some design aspects from the MP7 and then maybe did one better with the software to speed up the programming. I have had 1702As that only required one 3ms hit in the MIL to get a matching data byte. It can do a 1702A lickety-split.

    Craig

  7. #17

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    Dwight

    were the SIM4-01 and SIM4-02 contemporaries that were differentiated by price and capability or are they revisions that came out sequentially and the intent of the -02 was to replace the -01?

    Thanks

    Craig

  8. #18

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    Quote Originally Posted by candrews View Post
    Dwight

    were the SIM4-01 and SIM4-02 contemporaries that were differentiated by price and capability or are they revisions that came out sequentially and the intent of the -02 was to replace the -01?

    Thanks

    Craig
    The -02 had 16 RAM sockets and 16 ROM sockets. They both ran the same software but because the SIM4-02 had enough RAM to hold the entire 1702 code, it had a separate copy program, A0544. I wanted to be able to make copies easier on my SIM4-01 but with only 4 RAMs, I could only do 1/2 at a time so I wrote a program that did it in sequence, first read 1/2, program 1/2, read the second half, then program the second half. I used 4 of the lights on the MCB4-10 to sequence things for the person making the copies. The lights would all turn on any time there was an error in either the copy from master to RAM or after programming, the RAM to to the programmed EPROM. This way the operator new there was a problem. Depending on where it errored, one could also tell if one had bad RAM or programming failure. The MCB4-10 has a switch to turn the programming voltage. I always turned it off when the master EPROM was in the socket, just in case it didn't skipped a step. It used the switch for the TEST input to sequence the steps.
    Dwight

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