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  1. Replies
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    Pin 3 is N.C. (no connect) so that is right. ...

    Pin 3 is N.C. (no connect) so that is right.

    Pin 37 is the input clock (PHI0) so that is right.

    Pin 39 is the output clock (PHI2) so that is right - but without a 6502 CPU in place there is no...
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    There is something not right here. I think we are...

    There is something not right here. I think we are doubling-back on ourself...

    This logic probe should be able to resolve the frequencies we are talking about on the PET.

    Pin 7 of the VRAM is...
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    Pins 1 and 2 should definitely not be high - they...

    Pins 1 and 2 should definitely not be high - they should be pulsing. However, these two pins are the highest-frequency pulses than the others - and it could be that this is confusing your logic...
  4. Hey Mike, nice job... I would be in the market...

    Hey Mike, nice job...

    I would be in the market for both a green and amber - but live in the UK. If anyone else from the UK wants to 'chip in' then we could split the shipping between us?

    I am...
  5. Thread: Micro PDP 11/73

    by daver2
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    Gary, I hope this isn't the PDP-11 we have...

    Gary,

    I hope this isn't the PDP-11 we have been trying to find for 2 years now...

    It was 'put away safely' by someone on site - never to be found again :-)!

    Dave
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    Sorry, got myself confused! It happens...

    Sorry, got myself confused! It happens occasionally:-)!

    2532A EPROM plugged into an adapter which is (in turn) plugged into an EPROM programmer set to burn 2732A EPROMS.

    Ok, now I understand....
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    Yep, seen a good few examples (as will have many...

    Yep, seen a good few examples (as will have many people on here)...

    The best one I saw was a vaporised hole in a multi-CPU supercomputer...

    Our's only pulled 40 Amps. This one pulled in excess...
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    Don’t worry, you need to get a few posts under...

    Don’t worry, you need to get a few posts under your belt first and then the moderator’s will leave you alone. By adopting this approach, we get very little spam on the board - so it is worth the pain...
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    Just a sanity check here... You are not using...

    Just a sanity check here...

    You are not using your home-built adaptor with the EPROM in the programmer are you?

    If so, please donít!

    The EPROM you have is a 2532A. The ĎAí is important. If...
  10. Replies
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    Yep, 21V programming devices. No, the notch...

    Yep, 21V programming devices.

    No, the notch *** ALWAYS *** indicates where pin 1 is indexed from.

    I think Dwight is referring to the labelling, not the notch...

    Dave
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    Nope, I never found the documentation for the...

    Nope,

    I never found the documentation for the SBD+ in the end (unfortunately). I will keep an eye out though. You never know what I may find in an old box...

    Nice pictures though :-)!

    Dave
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    Looking at the photograph of the label (showing...

    Looking at the photograph of the label (showing how the cards should be installed) and the photographs of the cards themselves, there seems to be a couple of discrepancies:

    1. The M8650 serial...
  13. You can also put a low-valued series resistor in...

    You can also put a low-valued series resistor in line with your ammeter if you are worried about an appreciable current flow. OK, you won't be able to measure the actual current flow this way - but...
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    Can you remind us exactly what your devices are...

    Can you remind us exactly what your devices are (manufacturer, make and model) and what you set in your EPROM programmer?

    VPP over-current usually means there is a short circuit on the VPP line,...
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    >>> Do you have any links or other information...

    >>> Do you have any links or other information about DMS? Always curious...

    djg beat me to it.

    As djg says, start off small with a single serial port and the stand-alone languages and then...
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    True. I didn’t check the amount of memory...

    True.

    I didn’t check the amount of memory installed though.

    I saw the memory extension and assumed (always a bad thing).

    If only 4K there is the 4K DMS. This did require a disk/tape drive...
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    I wish I could find something like that in the...

    I wish I could find something like that in the trash! Nice find, especially in that good condition.

    The first thing is to resist the temptation to power it up as it is. Best case it will work....
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    I agree, that looks like the 'normal' keyboard. ...

    I agree, that looks like the 'normal' keyboard.

    The 'business' keyboard doesn't have the graphics symbols on the keys (after all, no one will want to play games and do programming on a business...
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    First of all - as this is your first post -...

    First of all - as this is your first post - welcome to VCFED.

    Do what dave_m asked first.

    Second, have a look on the main logic board for a couple of 40 pin black ICs with the number 6520 on...
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    If I remember correctly, this type of construct...

    If I remember correctly, this type of construct was used on the DEC PDP-8.

    I will have a quick look at the schematics later and see if it was in the later TTL implementation or the earlier...
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    Hi Kenny, welcome to our community. It is...

    Hi Kenny, welcome to our community.

    It is usually best to add your location to your profile - so that responders to your posts know where you live.

    You will find that your posts are moderated...
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    Not sure where you are in the world, but plenty...

    Not sure where you are in the world, but plenty available here https://www.jameco.com/z/6502-Major-Brands-IC-6502-8-Bit-MPU_43191.html.

    Only buy from China if you are (a) really stuck for the part...
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    Well done... Dave

    Well done...

    Dave
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    You will find the schematics you need over at...

    You will find the schematics you need over at http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/pet/2001/index.html.

    Just beware there are multiple versions of the PET main board - so...
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    What I am seeing in your first video is correct....

    What I am seeing in your first video is correct. With the two (2) video rams removed (C3 and C4), the default data outputs (well, actually the inputs to the character generator A2) will all be HIGH -...
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