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  • daver2's Avatar
    February 18th, 2019, 07:05 AM
    daver2 replied to a thread Its Back!!! IMS 8000 in S-100
    I have some Intel P2114ALS devices here at work (brand new with a Certificate of Conformance...) - if you only need a couple. Send me a PM with...
    10 replies | 241 view(s)
  • daver2's Avatar
    February 10th, 2019, 11:32 AM
    daver2 replied to a thread What is this guy? in CP/M and MP/M
    So you did get the computer with the disk drive :-)! Dave
    12 replies | 821 view(s)
  • daver2's Avatar
    February 5th, 2019, 12:36 PM
    Based on the fact that you say the O1 with the keyboard cable (but no keyboard) works OK, I would say there isn't a fault with the main logic...
    74 replies | 3260 view(s)
  • daver2's Avatar
    February 3rd, 2019, 03:56 AM
    >>> but it seems we're doing autopsies, with little possibility of resurrections. To carry on with the medical analogy - I think the patient is...
    74 replies | 3260 view(s)
  • daver2's Avatar
    February 2nd, 2019, 09:38 AM
    Cheers. Very useful to me. Dave
    37 replies | 2010 view(s)
  • daver2's Avatar
    February 2nd, 2019, 06:27 AM
    daver2 replied to a thread PDP-8L Modules in DEC
    Firstly, good going on your find! You may be able to find someone willing to give/sell you the requisite boards. They do come up on e-bay...
    7 replies | 371 view(s)
  • daver2's Avatar
    February 2nd, 2019, 03:09 AM
    The people that have mentioned balanced and unbalanced interconnections are on the money! I am on the A/V team at our Church and was the original...
    6 replies | 228 view(s)
  • daver2's Avatar
    February 2nd, 2019, 12:48 AM
    Do you want to continue with this or are you going to go down the route of replacing the keyboard with something else? I have two weeks 'spare'...
    74 replies | 3260 view(s)
  • daver2's Avatar
    February 2nd, 2019, 12:36 AM
    Well done that man (once again)... Can you still read the manufacturer, date code and part number from the bits of the chip? I would also be...
    37 replies | 2010 view(s)
  • daver2's Avatar
    February 1st, 2019, 09:30 AM
    daver2 replied to a thread Tektronix 'Board Bucket' 6800 in Other
    Defective chips would do it! The TAPE command stores an entered BASIC program to the serial port that can be subsequently loaded with the LOAD...
    126 replies | 11447 view(s)
  • daver2's Avatar
    February 1st, 2019, 08:33 AM
    daver2 replied to a thread D.R.E.A.M. 6800 Build in Other
    >>> For some reason, the system is always outputting a leader tone. I don't know if that's by design or what the deal is. By design, 2400 Hz is...
    60 replies | 2930 view(s)
  • daver2's Avatar
    January 31st, 2019, 11:39 AM
    daver2 replied to a thread D.R.E.A.M. 6800 Build in Other
    Yes, you are correct in that a BLACK screen indicates that CHIPOS is dumping or loading to/from tape. To record (dump) data, set-up the memory...
    60 replies | 2930 view(s)
  • daver2's Avatar
    January 31st, 2019, 08:49 AM
    daver2 replied to a thread D.R.E.A.M. 6800 Build in Other
    Are you setting up memory addresses 2, 3, 4 and 5 with the start and end+1 addresses BEFORE you save ***AND*** BEFORE you load? I am not sure what...
    60 replies | 2930 view(s)
  • daver2's Avatar
    January 31st, 2019, 08:38 AM
    daver2 replied to a thread Tektronix 'Board Bucket' 6800 in Other
    Did you use the snoopy data from post #110? The strings appear to be limited to 32 characters maximum length. Dave
    126 replies | 11447 view(s)
  • daver2's Avatar
    January 28th, 2019, 10:36 PM
    Another PET successfully resurrected :-). Enjoy. Dave
    102 replies | 5671 view(s)
  • daver2's Avatar
    January 28th, 2019, 10:34 PM
    daver2 replied to a thread D.R.E.A.M. 6800 Build in Other
    It took me a few times to understand the article as well... I would checkout the keypad with a multimeter set to continuity. Find the row and...
    60 replies | 2930 view(s)
  • daver2's Avatar
    January 28th, 2019, 12:29 PM
    If this pin is floating it has probably more to do with electromagnetic interference than light. Dave
    102 replies | 5671 view(s)
  • daver2's Avatar
    January 28th, 2019, 12:06 PM
    Pin 18 on a 2732A should be hard connected to ground/0V for it to work properly. Not pulled-up or floating. If pin 18 was pulled-up high - the...
    102 replies | 5671 view(s)
  • daver2's Avatar
    January 28th, 2019, 11:46 AM
    daver2 replied to a thread D.R.E.A.M. 6800 Build in Other
    I don't know what manual you are reading - but that is not the same as the manual I am reading. To edit the display buffer you enter the following...
    60 replies | 2930 view(s)
  • daver2's Avatar
    January 28th, 2019, 11:30 AM
    I can't remember now whether you put electrons into an EPROM cell to change the logic sense (when read) from a '1' to a '0' - or remove them (i.e....
    102 replies | 5671 view(s)
  • daver2's Avatar
    January 27th, 2019, 11:07 PM
    Last time I came across this exact fault it was a dicky EPROM... it must have been the EDIT EPROM I think... The owner put an LED above the EPROM...
    102 replies | 5671 view(s)
  • daver2's Avatar
    January 27th, 2019, 02:57 PM
    daver2 replied to a thread D.R.E.A.M. 6800 Build in Other
    Is the CPU running? Pin 40 (/RST) should be high. Pin 2 (/HALT) should be oscillating - but not permanently high or low. Pin 5 (VMA) should be...
    60 replies | 2930 view(s)
  • daver2's Avatar
    January 27th, 2019, 12:24 PM
    daver2 replied to a thread Bought a PDP-11/03-L in DEC
    There are four additional address lines bussed on the 22-bit backplane - so you can check these pins from the 'front' with a cheap and cheerful...
    65 replies | 4196 view(s)
  • daver2's Avatar
    January 27th, 2019, 12:20 PM
    daver2 replied to a thread Tektronix 'Board Bucket' 6800 in Other
    Yes, it's quite impressive isn't it! I have a partial hand disassembly of DDT and I fed it through f9dasm. I need to enter the data areas I have...
    126 replies | 11447 view(s)
  • daver2's Avatar
    January 27th, 2019, 10:18 AM
    daver2 replied to a thread What is this guy? in CP/M and MP/M
    Never seen one like that before - but (from the photographs) I wouldn't have been surprised to find another board tucked under that drives (as you...
    12 replies | 821 view(s)
  • daver2's Avatar
    January 27th, 2019, 10:03 AM
    daver2 replied to a thread D.R.E.A.M. 6800 Build in Other
    I am getting really slow in my old age!!! I have just looked back at M.J. Bauer's website and noticed a ZIP file there that I hadn't seen before...
    60 replies | 2930 view(s)
  • daver2's Avatar
    January 27th, 2019, 09:35 AM
    daver2 replied to a thread D.R.E.A.M. 6800 Build in Other
    Just looking at the original schematics - and can't see any other components in-line with the tape in or tape out connectors. On the PCB there is...
    60 replies | 2930 view(s)
  • daver2's Avatar
    January 27th, 2019, 09:02 AM
    daver2 replied to a thread Tektronix 'Board Bucket' 6800 in Other
    README.TXT file uploaded (probably with half a dozen spelling mistakes)... Enjoy... Dave
    126 replies | 11447 view(s)
  • daver2's Avatar
    January 27th, 2019, 08:22 AM
    daver2 replied to a thread Tektronix 'Board Bucket' 6800 in Other
    OK, The ROM files basic.bin and ddt.bin have been uploaded to https://drive.google.com/open?id=1ctaYD5Pwifz0N2-VN0h50mZUVbKq6cZB. BASIC is 8K...
    126 replies | 11447 view(s)
  • daver2's Avatar
    January 27th, 2019, 08:02 AM
    daver2 replied to a thread Tektronix 'Board Bucket' 6800 in Other
    Will do when I have warmed up and had my coffee (just got back from my daily walk)! What format is best for you to handle? Just plain old binary?...
    126 replies | 11447 view(s)
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About daver2

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About daver2
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UK - Worcester
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SW/HW design engineer

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