Image Map Image Map

Search:

Type: Posts; User: Dwight Elvey

Page 1 of 20 1 2 3 4

Search: Search took 0.26 seconds.

  1. Most memory test are only look to see if the...

    Most memory test are only look to see if the location can read and write. Address faults can go untested. Early on, many used GALPAT but it grows in exponentially with memory size. Then "March C" was...
  2. RS232 got messed up by a number of applications....

    RS232 got messed up by a number of applications. Some uses don't need or use hand shake. Male and female connectors get mixed up. Not all follow the rules. I tend to ignore what it is suppose to be...
  3. You may still need to rewire some. It could be...

    You may still need to rewire some. It could be straight through or need a null modem. It always helps to have a RS232 breakout box to crisscross the wires as needed to make both ends happy.
    Dwight
  4. Other than common text functions like home, clear...

    Other than common text functions like home, clear screen, CRLF and scroll. Locating to an XY is about all that is need, that I can think of.
    Dwight
  5. Replies
    123
    Views
    7,703

    I'm not a Pet expert but the fact that is waits...

    I'm not a Pet expert but the fact that is waits to see a key pressed to bring on the signon, leads me to think the computer is seeing a constant key press or something. Maybe related to an interrupt....
  6. It really depends on which escape sequences you...

    It really depends on which escape sequences you intend to support. Most software is relatively limited.
    Dwight
  7. Yep, I hadn't thought of that. Dwight

    Yep, I hadn't thought of that.
    Dwight
  8. For the first one, just replace the resistor. I...

    For the first one, just replace the resistor. I doubt it is critical that it is a 1% but these are easily available.
    For the second one that the buttons work but not the mouse ball. It is likely...
  9. I don't know of any generic CP/M applications...

    I don't know of any generic CP/M applications that assume memory mapped video. That is at the bios level. CP/M assumes one byte at a time going to a terminal. It has no idea how that terminal...
  10. I'm more concerned that the first picture is not...

    I'm more concerned that the first picture is not the same board as the second picture. The OP has got to be consistent or we are just guessing as to what it is expecting of us. The second is a...
  11. I don't see the problem. CP/M was intended to be...

    I don't see the problem. CP/M was intended to be able to revector both input and output. You just need the serial I/O handler code and select between the two as needed. While running Xmodem, you...
  12. Before removing the stepper and losing the track...

    Before removing the stepper and losing the track zero adjustment, check that the control signals to the stepper are working correctly. It is common that one of the phase drives to the stepper will...
  13. I believe the orange band is a thermal...

    I believe the orange band is a thermal coefficient and not the first band, note the spacing. I believe the value would be 121 ohms, 1%. The second picture is not the same mouse board. I'm not sure...
  14. The hamming distance of a check sum is 1. That...

    The hamming distance of a check sum is 1. That means 2 bits being wrong can cause a missed error, for many 2 bit errors. XOR by it self is even worse.
    Dwight
  15. Replies
    18
    Views
    220

    If I have the right schematic. UE-12 is a 74154....

    If I have the right schematic. UE-12 is a 74154. It decodes all the blocks of address for the top 4 address bits, A12, A13, A14 and A15. Looking at the decoded outputs, you can see which address...
  16. Replies
    18
    Views
    220

    You might check the address decoder lines to see...

    You might check the address decoder lines to see what address it is stuck at. There are 16 possible places to get stuck.
    If you have a digital scope, you can usually see data before the trigger. If...
  17. It could also be a FIB as well. Both an electron...

    It could also be a FIB as well. Both an electron microscope and a FIB would have a long column for focusing the beam.
    Dwight
  18. If you have space for 256 byte table, the CRC can...

    If you have space for 256 byte table, the CRC can be as simple as one table look up, using the current byte as an offset and one XOR per each byte fetched. That is about as simple as it gets and much...
  19. Replies
    43
    Views
    1,259

    Life happen some times. Dwight

    Life happen some times.
    Dwight
  20. The computer is a HP. Above it is a Diablo 30...

    The computer is a HP. Above it is a Diablo 30 hard disk drive or different version with a paper tape above that. It looks like an electron microscope in the back but these are usually mounted...
  21. Replies
    20
    Views
    3,352

    No. Often for a single card, it is not done. It...

    No. Often for a single card, it is not done. It likely expects multiple cards.
    It might need a change of the address mux as well. I know that for the Olivetti M20 it requires changes at the address...
  22. If you have a windows machine, you can use Paint...

    If you have a windows machine, you can use Paint program to reduce them. You need to experiment as the program expects a pixel dimensions.
    Dwight
  23. Replies
    20
    Views
    3,352

    I don't think it is designed to take 41512 chips....

    I don't think it is designed to take 41512 chips. You'll likely only see the 128K, with those chips. It may only do 256K but I'd be suspicious of that.
    Dwight
  24. Never used one. Dwight

    Never used one.
    Dwight
  25. A momentary value that changes to OL is not a...

    A momentary value that changes to OL is not a value. It is opened. You are seeing a capacitance that is someplace else in the circuit that is in parallel with the resistor. That momentary value is...
Results 1 to 25 of 500
Page 1 of 20 1 2 3 4