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Thread: Tektronix 4041 computer from the early 1980's - WORKING!!

  1. #1

    Default Tektronix 4041 computer from the early 1980's - WORKING!!

    I had purchased two of these Tektronix 4041 computers in 2000 after acquiring my 4052 computer.

    I thought I would use them as GPIB test automation controllers for a TM500 with relay modules and digital multimeter - but never got around to doing that project.

    I did capture the ROMs and plan to post them on my Tektronix 4050 github repository.

    Both of the 4041 had the Programming Development Option ROMs, and one also had Graphics ROMs, Plotting ROMs, Signal Processing, and Utility #1 ROMs!

    I purchased the 4041 Operating and BASIC Programming manuals, but never had the Option ROM manuals. I found they have been posted on bitsavers - I'll have to check them out.

    I plugged both units in - both powered up and completed self tests - both have 512KB of RAM.

    The Tektronix 4041 used a Motorola 68000 CPU, and had similar BASIC ROM commands to the 4051/4052/4054.

    The 4041 has a one line text display and a built in DC100 tape drive and small thermal printer. The thermal printer isn't working on the one I tested today, maybe when I test the other one - the printer will work.

    Here is a photo of the 4041 - auto loaded the System Verification tape that I had!

    I had received the 4041 System Verification tape from Stan Griffiths in 2000, along with a box of 4051 tapes.

    All three DC100 tapes I had with my 4041 had broken drive belts. I got the tapes working with 4 1/4 inch Plastibands from Amazon:

    Here is a photo of the CPU board - there is a small board on the left on top of the CPU board with the ROMs - so you can't see the 68000 CPU.

    Searching the web - it appears no one has posted the service manual for the 4041.

    The tape on top of the 4041 had a label I wrote: "SERIAL 1 mcm 5/24/00".

    Looking at the operators manual - it indicates that you can configure the 4041 console to use an external terminal (but you have to load a program from tape to do that).

    In order to create a program on the 4041 you must have the Programming Development option ROMs - and use the keyboard connector on the front panel.

    I never had the keyboard and must have hacked into the four-pin LEMO connector on the front panel. The manuals don't give a pinout for that connector, but I saw a post this morning that indicated it is 5V serial TX/RX, so I must have also used a level converter to create the SERIAL 1 program.

    When I was able to auto load the SERIAL 1 tape - I hooked up my laptop with a USB serial converter, but had to experiment to remember the port speed and configuration. It was 9600 7S1 with XON/XOFF.

    My next post will list the SERIAL 1 program, and the directory listing of the System Verification Tape.
    Last edited by nikola-wan; May 24th, 2020 at 01:13 PM.

  2. #2


    I spent quite a while today recovering all the files on the 4041 System Verification Version 2.8 tape.

    Here is the directory listing of all the files on that tape:

    SYSVER 2.8 29-APR-85 09:46:04  SOFT ERRORS = 0        
     FILE  FILE  LENGTH  START  NUMBER         LAST       
    ------ ---- -------- ------ ------- ------------------
    AUTOLD  IT     2550     5     10    13-SEP-84 16:08:00
    TERMIN  IT     8160    15     32    13-SEP-84 16:08:00
    SYSVER  IT     3570    47     14    13-SEP-84 16:09:00
    CONFIG  AS      510    61      2    01-JAN-81 00:02:00
    PROCED  IT     1020    64      4    13-SEP-84 16:09:00
    LINK    IT      765    68      3    13-SEP-84 16:09:00
    DISP    IT     1275    71      5    13-SEP-84 16:09:00
    KEYPAD  IT     1530    76      6    13-SEP-84 16:09:00
    PRINTE  IT      765    82      3    13-SEP-84 16:09:00
    TAPE    IT     4590    85     18    13-SEP-84 16:10:00
    SOFTER  IT      765   103      3    13-SEP-84 16:10:00
    IO      IT     4590   106     18    13-SEP-84 16:10:00
    TIMER   IT     1530   125      6    13-SEP-84 16:10:00
    PDKYBD  IT     4335   131     17    13-SEP-84 16:11:00
    GPIB    IT     2040   148      8    13-SEP-84 16:11:00
    GPIBLB  IT     3315   156     13    13-SEP-84 16:11:00
    GPIBCO  IT     2040   169      8    13-SEP-84 16:11:00
    SLAVE   IT     3315   177     13    13-SEP-84 16:11:00
    MASTER  IT     1785   190      7    13-SEP-84 16:12:00
    PAUS    IT      765   197      3    13-SEP-84 16:12:00
    TPCAL   IT     1275   200      5    13-SEP-84 16:12:00
    PTRCAL  IT     1020   205      4    13-SEP-84 16:12:00
    FRMAT   IT     1020   209      4    13-SEP-84 16:12:00
    TSTPTN  IT     2040   213      8    13-SEP-84 16:12:00
    CHKOPT  IT     1275   221      5    18-SEP-84 13:04:00
    OPT2    IT      765   226      3    13-SEP-84 16:12:00
    HELP    IT     3060   229     12    13-SEP-84 16:12:00
    PDTEST  IT      255   241      1    13-SEP-84 16:12:00
    SCSI    IT     2550   242     10    13-SEP-84 16:13:00
    TSYSVR  AS     4080   252     16    13-SEP-84 16:13:00
    TSCSI   AS     3315   268     13    13-SEP-84 16:13:00
    TDIR    AS     2295   281      9    01-JAN-81 00:25:00
    I created a new github repository for the Tektronix 4041 GPIB Controller:

    I have posted all the files recovered from the tape, and added a folder with the ASCII text version - as all the programs were written to the tape in ITEM form (Tektronix binary).

    I will be posting all the ROMs that I captured back in 2000 when I finish converting them to binary.

    One of the most interesting is the Utility ROMs that include a PROM File System! They talk about a kit to program tape files into a PROM that will then boot the 4041 if the AUTOLD file is on the PROM.

  3. #3


    Here is a photo of the Tektronix 4041 Option ROM carrier tray with all the available Options:

    There was a Utility ROM #2 but apparently it was added to the internal ROMs at some version - don't know how to check if I have that yet.

    This tray is behind the grill in front of the 4041 - grill is removed and off to the side of the ROM carrier tray in this photo.


  4. #4


    I just uploaded all the Option ROM files, and the combined 16-bit files to my 4041 github repository. I checked all the individual binary ROM checksums against what my Data I/O reported in 2000 when I captured the files - everything checks out.

  5. #5


    Nice system, I guess that these machines were mostly used for laboratory use?
    It looks a bit like a PLC. How do the ROM modules connect to the system? Are there pins at the bottom?
    WTB: Case for Altair 8800 ...... Rolands Github projects

  6. #6


    Quote Originally Posted by Roland Huisman View Post
    Nice system, I guess that these machines were mostly used for laboratory use?
    It looks a bit like a PLC. How do the ROM modules connect to the system? Are there pins at the bottom?

    Yes, Tektronix targeted the 4041 as a GPIB controller to automate testing.
    Tektronix also had a product line of modular GPIB test equipment that plugged into TM5000 power chassis.

    Here is a photo I found of a TM5000 chassis with digital multimeter, programmable power supplies, signal generators, relay modules, A to D and D to A converters, ...

    Not a very glamorous application - but I imagine this gear has been in continuous use in labs since the 1982 introduction.

    There are still 4041's and TM5000's for sale on EBAY.

    I have a TM5000 with digital multimeter, relay modules and A/D modules - I plan to post more info on that in the future.

    My other thought in reviving my 4041's - they have similar BASIC commands to the 4050 computers, and support using the 4050 computers as graphics terminals.
    Since the 4041 has a 68000 with 512KB of memory - I want to experiment with the 4041 driving my 4052 and 4054A computers.

  7. #7


    Quote Originally Posted by Roland Huisman View Post
    Nice system, I guess that these machines were mostly used for laboratory use?
    It looks a bit like a PLC. How do the ROM modules connect to the system? Are there pins at the bottom?

    I didn't answer your second question - the ROM carrier has an edge card connector on the back that connects all the ROMs to the 68000 memory bus.

    The Molex sockets in the ROM carrier were designed to mate with each EPROM with the leads bent around Molex leadframes, with keys to prevent the EPROMs from being inserted backwards.

    The bottom of the ROM carrier has slots that create twelve ejectors to push each of the EPROMs out of the carrier socket. The brown posts in the middle of each socket in the photo above are connected to the ejectors.

    Here is the back view of the Option ROM holder with one EPROM removed. Note each end of the leadframe has different key shapes on both ends to prevent EPROMs being installed upside down.

  8. #8

    Default Success! I made a copy of the 4041 System Verification Tape!

    I successfully created a copy of the System Verification tape and tested it on my 4041 without the ROM Carrier and Program Development ROMs installed!

    Quite an effort - I received the 15 DC100A NOS tapes Sunday and spent the rest of the day trying to record on one of them - unsuccessfully.
    The belt was not broken when I took off the shrink wrap - but it broke immediately when I pressed the AUTO LOAD button on the front panel.

    I replaced the belt with one of the 4 1/4" Plastibands and tried multiple times to format the tape but kept getting errors. The band kept popping off and the tape head was getting clogged with 'tape shed' and the two guide posts collected 'tape shed' and the tape would stick.

    An internet search turned up a youtube video from Curious Marc that itemized several different issues with trying to recover the data from old DC100 tapes in an HP computer - I was seeing most of those issues with these NOS tapes. I believe these five tapes are from 1993, a second box 1992 and the third box from 1991 - based on the publishing date on one of the papers inside the case with each tape.

    The solution recommended in the video was to 'bake' the tapes at 135 degrees F in a dehydrator.

    I went looking for tape 'baking' instructions, and said his best results were from baking for two days.

    I opened up the other four tapes, removed the plastic belt rollers, the capstan and taped the two drive reels together as recommended with the tape directly between the two reels.

    I have an Excalibur dehydrator and set the control to 135F. I put all five NOS tapes in the dehydrator, numbering each on the 'invisible tape'. I measured the temp of the tapes multiple times during the two days with an infrared temp sensor - got within one degree of 135F every measurement.

    Instructions indicated letting the cartridges cool for an hour - I waited longer than that.

    First I tried reassembling tape #1 that I was unable to use on Sunday - with a fresh Plastiband belt. The 4041 kept indicating an Invalid Tape error. Possibly from previous recording attempts.

    I then put tape #1 aside and picked tape #2, fresh band, plugged it in and got CRC error when I pressed AUTO Load. I was able to format the tape and began writing one file at a time to the tape, checking the directory list after each operation. I had to replace the belt a couple of times, and retension a couple of times, but got all the files written.

    Here is the resulting directory list of my first System Verification Tape copy. Notice that I didn't put a tape name in the FORMAT command, and didn't SET TIME until several files were recorded.

    My process steps were not quite correct - here is a new sequence, after you have bootstrapped the console to COMM: (COMM0: if you have two serial ports)

    1 - SET TIME
    2 - Format the tape, recommend adding the parameter to name the tape
    3 - Select an ASCII file to SEND with Realterm
    4 - Start the transfer - you will see the lines of the program on the Realterm window
    5 - Select the Realterm console window in order to type commands to the 4041
    6 - SAVE "filename(OPE=NEW,CLI=YES,FOR=ITEM)"
    7 - If you don't get an error, type DIR and check that 'filename' is at the end of the DIR and the correct type (IT) and filesize. If error, DELETE FILE "filename" and do STEP 6
    8 - LOAD "COMM:" then press front panel "ABORT" button. This clears the previous program in memory.
    9 - now repeat starting with STEP 3 until done

    Here is my tape copy long directory list. Only file that didn't match length with original is the last file TSCSI.ASC.
    I actually I wrote both the TDIR and CONFIG files in 2000 - note the file dates are the 4041 default of 1981 if the SET TIME command is not run.

    From the timestamps - it took me three hours to write the files to the tape.

               01-JAN-81 00:15:50  SOFT ERRORS = 21       
     FILE  FILE  LENGTH  START  NUMBER         LAST       
    ------ ---- -------- ------ ------- ------------------
    AUTOLD  IT     2550     5     10    01-JAN-81 00:28:00
    TERMIN  IT     8160    15     32    01-JAN-81 00:40:00
    SYSVER  IT     3570    47     14    01-JAN-81 00:44:00
    CONFIG  AS     1020    61      4    01-JAN-81 00:50:00
    PROCED  IT     1020    65      4    01-JAN-81 00:59:00
    LINK    IT      765    69      3    01-JAN-81 01:01:00
    DISP    IT     1275    72      5    03-JUN-20 19:33:00
    KEYPAD  IT     1530    77      6    03-JUN-20 19:37:00
    PRINTE  IT      765    83      3    03-JUN-20 19:41:00
    TAPE    IT     4590    86     18    03-JUN-20 19:43:00
    SOFTER  IT      765   104      3    03-JUN-20 19:45:00
    IO      IT     4590   107     18    03-JUN-20 19:48:00
    TIMER   IT     1530   125      6    03-JUN-20 19:49:00
    PDKYBD  IT     4335   131     17    03-JUN-20 20:01:00
    GPIB    IT     2040   148      8    03-JUN-20 20:10:00
    GPIBLB  IT     3315   156     13    03-JUN-20 20:12:00
    GPIBCO  IT     2040   169      8    03-JUN-20 20:13:00
    SLAVE   IT     3315   177     13    03-JUN-20 20:15:00
    MASTER  IT     1785   190      7    03-JUN-20 20:17:00
    PAU     IT      765   197      3    03-JUN-20 20:21:00
    TPCAL   IT     1275   200      5    03-JUN-20 20:23:00
    PTRCAL  IT     1020   205      4    03-JUN-20 20:25:00
    FRMAT   IT     1020   209      4    03-JUN-20 20:27:00
    TSTPTN  IT     2040   213      8    03-JUN-20 20:37:00
    CHKOPT  IT     1275   221      5    03-JUN-20 20:39:00
    OPT2    IT      765   226      3    03-JUN-20 20:56:00
    HELP    IT     3060   229     12    03-JUN-20 21:00:00
    PDTEST  IT      255   241      1    03-JUN-20 21:05:00
    SCSI    IT     2550   242     10    03-JUN-20 21:07:00
    TSYSVR  AS     4080   252     16    03-JUN-20 21:09:00
    TSCSI   AS     4590   268     18    03-JUN-20 21:19:00

  9. #9


    I paid for scans of the latest 4041 Controller Service Manual (Vol1 070-6965-00 and Vol2 070-6966-00), and the 4041 DDU (disk drive unit) service manual (070-5853-00).

    Here is a snapshot of the pdf front page of the service manuals:

    If you would like either set of scans please send me a PM on this forum.



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