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Thread: Tektronix 4052

  1. #31
    Join Date
    Jul 2012
    Location
    Switzerland
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    149

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    Remove the 68B50 from the MFM module. Maybe there is a conflict there ....

  2. #32

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    Quote Originally Posted by jdreesen View Post
    Remove the 68B50 from the MFM module. Maybe there is a conflict there ....
    Hi Jos,

    The MFM module was not in the system while testing the TransEra serial module...
    So no conflicts at that moment... Good to know for the possible problems in the future.

    Regards, Roland
    WTB: Case for Altair 8800 ...... Rolands Github projects

  3. #33

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    Quote Originally Posted by Roland Huisman View Post
    According the TransEra manual the default BAUD rate at power on is 9600 BAUD.

    But with simple command like PRINT @41: "Hello World!" the I/O lamp goes on and the machine locks up.
    Hitting the break button two times hands over control to the user again. So it seems to wait for data or a response.
    I've been playing with the jumper settings to disable DTR, because I was wondering if it was waiting for a clear to sent signal.

    But somehow I can't use the module. Also some strange behaviour on other settings...


    Regards, Roland
    Roland,

    I think this is good progress.

    Page 1-2 in your manual indicates the RS-232 module uses DTR/CTS hardware handshake. The second paragraph indicates when DTR is not asserted by the external device - the ROM pack waits if it is outputting data.

    Third paragraph indicates CTS in the ROM pack is the output signal to the external device to indicate the ROM pack is NOT ready for data from the external device.

    Realterm supports hardware flow control but uses either DTR/DSR or RTS/CTS signals. If you have an RS-232 breakout box between the 4052 and your PC, rewire the ROM Pack DTR/CTS to either RTS/CTS or DTR/DSR on the PC cable side.

    Or if you want a simpler test - just jumper the ROM Pack DTR pin to +12V inside the ROM pack, and retry your PRINT hello world test without any cable attached to the ROM pack. This should allow the PRINT command to complete without locking up waiting for DTR.

    Monty

  4. #34

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    Roland,

    Your TransEra RS-232 ROM Pack includes all the jumpers you need!

    Try jumpering your ROM Pack like my diagram below and configure Realterm for RTS/CTS hardware handshake. You may need to reverse the RTS/CTS or TX/RX based on your cable.



    Monty

  5. #35

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    Roland,

    My last diagram was not very clear.

    This diagram shows the jumpers I see in your board photo, followed by my recommended configuration of all the jumpers (several jumpers not needed):

    My suggested jumpers2.jpg

    Monty

  6. #36

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    Hi Monty,

    Quote Originally Posted by nikola-wan View Post
    Or if you want a simpler test - just jumper the ROM Pack DTR pin to +12V inside the ROM pack, and retry your PRINT hello world test without any cable attached to the ROM pack. This should allow the PRINT command to complete without locking up waiting for DTR.
    That was what exactly what I have done right after the lock up behaviour as you can read in #30, because I like to cancel out all other possible errors right away. I used jumper settings from schematic B-2 to be precise. But it keeps locking up the machine. Unfortunately I don't have an extender card. Would be nice to have to measure on the board...

    I'm still waiting for the RS232 driver chips for the MFM module. When I have these I guess I can use the MFM to load programs into the machine?

    Regards, Roland
    Last edited by Roland Huisman; August 16th, 2020 at 01:40 AM.
    WTB: Case for Altair 8800 ...... Rolands Github projects

  7. #37

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    I have received the last parts for the MFM module. So I could try to use that module to upload software.
    But I think the commands will be different. Any info on how to use the serial port on the MFM module?
    I guess that in the first slot the addresses will be @41...@48 ? But at which address is the serial port?

    Regards, Roland
    WTB: Case for Altair 8800 ...... Rolands Github projects

  8. #38

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    Roland,

    I think your MFM ROM image has the wrong RS232 image. I think that ROM is stored at 08000 - the third 16KB ROM pack slot.

    If you have a programmer that can read and write that EPROM, look at address 8010 hex, 40, 52 needs to be at address 10 hex.

    If it isn't there - look at address 9010 and if you find 4052 there - that is the good part of the RS232 ROM.

    Copy the 4KB block from 9000 to 9FFF to 8000 to 8FFF.

    I'm having issues with testing my MFM board from Jos - I can't get the RS232 to work with the MFM in the left slot.

    Jos's MFM doc indicates how to change the two-slot backpack board so the MFM RS232 will be decoded as the Option 1 - and you won't need to fix the MFM ROM - you will be using the full featured BASIC support for Option 1.

    Variants :
    - for those with only the firmware backpack board : with a small change of the firmware
    backpack PCB ( move "xpc2" signal from U361 pin 13 to pin 14 ) the printer serial interface will
    assume the role of the main RS232 interface of the communications backpack. ( within
    limitations of the MFM hardware i.e. no programmable baudrate, as the necessary chip is not
    present. Not tested, and not for 4051 which needs a separate baudrate-clock)

    I'm still trying to debug why my MFM is rebooting my 4052 and 4054A - so I suggest you try rewiring your backpack backplane as above - then you should be able to use the RS-232 connector at GPIB address 40 (LIST @40:, PRINT @40: etc).

    Monty

  9. #39

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    Hi Monty,

    I used the ROM versions that Jos has on his ftp. I burned proms with the 52V1 and 52V2 eprom files.
    And I just wondered if Jos could use the ROM image of the TransEra RS232 module in the MFM unit

    This is the circuit board in the 4 slot module.
    PCB expansion module.jpg

    The schematic of my backplane circuit board is on page 5 from document 4052_schematics-chap07-10.pdf
    I checked the schematics. The LS138 which Jos talked about is also in the 4 pack expansion.

    The version with RS232 shows the line from the LS138 to enable the 6850
    Schematic expansion module with rs232.jpg

    That LS138 is present at my board too and indeed an open output which I could use.
    Schematic expansion module.jpg

    I think it is a shame that Tek didn't use the same board and just left some components out.
    Instead of that they made a completely different PCB. Probably to prevent that people like me
    would expand the machine without paying big money to Tektronix...

    I would like to hear some advice. What would be better, use the wire to enable the
    original Tektronix RS232 capabilities? Or wait for an updated ROM version?
    Is there a problem using an interface other than the Original Tek RS232 port?

    I just don't prefer wires soldered between pluggable modules and the machine...

    Edit: Just thinking to hack an 74LS138 into the MFM module. All the necessary input signals seem to be there...

    Regards, Roland
    Last edited by Roland Huisman; August 30th, 2020 at 03:38 AM.
    WTB: Case for Altair 8800 ...... Rolands Github projects

  10. #40
    Join Date
    Jul 2012
    Location
    Switzerland
    Posts
    149

    Default

    Roland,

    just make a temporary connection inside the backplane module and use the original ROM software ? And try things out

    Mind you there still seem to be some issues with my MFM module, as both me and Monty get occasional resets of the whole machine.

    Jos

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