开云体育

I just received my EBAY purchase of another 4041 - this time with the DDU
disk drive unit attached.

The auction indicated they were working at the time they were taken out of
service - I'm not so sure of that, but both 4041 and DDU powered up during
my test last night.

However, even though the 4041 powered up, showed v2.1 firmware and 512KB
of memory, the LED display showed a prompt, so I suspected it did not load
any AUTOLD file from the DDU.

There are SCSI DIP switches on the 4041 rear panel for SCSI Option 03, one
of which changes the default storage from internal tape drive to DDU hard
disk - and that switch was set to DDU hard disk.

Looking at the front of the DDU, I could see the hard drive LED blinking
three times, repeatedly. The DDU service manual indicated in the Shugart
hard drive section that this meant the spindle failed to come up to speed :(

I turned off both units and changed that switch to tape, powered up the
4041 by itself with one of my tapes, but got an error on the LED display
indicating 840 Lamp/Servo failure.

The tape did not move, so it appears I need to troubleshoot the tape Lamp
circuit.

In the meantime, I pulled off the right side cover and did my front panel
board mod to allow my USB to TTL serial adapter to be used with the front
panel keyboard connector.

- Power off the 4041.
- Remove the 4041 two rear plastic "corners" securing the right panel and
slide off the right panel.
- I dipped my desolder braid in flux, place the braid on the pad and apply
your hot soldering iron to the braid and resistor lead to suck the solder
completely from the pad. Be sure to cut off the braid and apply fresh flux
before desoldering the pad for each resistor.
- Unsolder and lift the 'left' side of the two resistors closest to the
unused J86 connector as shown in my resistor mod photo: [4041 Resistor Mod](
/g/TekScopes/photo/247590/4?p=Created,,,20,2,0,0)
- Solder a 1K ohm resistor into the hole (I first cut the resistor lead
down to .25 inch).
- Then solder the tomb-stoned 1K ohm resistor to the lower resistor and
clip off any extra leads per my photo
- Replace the right side panel to ensure proper 4041 cooling.
- Connect your TTL Serial interface ground to the top left keyboard
connector female contact.
- Connect your TTL Serial interface TX to the lower left keyboard
connector male pin.
- Configure your TTL Serial interface for 4800N2 speed, parity, stop bits.
- Power on the 4041 and you should be able to type on your PC using the
TTL Serial interface - and see your typed characters on the front panel LED

I only use this TTL Serial interface to bootstrap to the rear panel COMM0
interface (if you have the Programmer ROMs installed in the ROM tray behind
the front panel grill):
1. Type "SET DRIVER "COMM0(BAU=9600,FLA=BID,EDIT=STORAGE):"
2. Type "SET CONSOLE "COMM0(ECHO=YES):"

I find the EDIT=STORAGE parameter is easier to use when correcting PC
typing errors, as the console will echo back each character you are
deleting.

After the 4041 keyboard mod, I used my PC to type the command to format a
DDU 5 1/4" floppy, and to run the DDU service manual program to do write
and read performance tests on the floppy.

I got 1117 Bytes per second, which meets the 1000 bytes per second listed
in the floppy spec.

So my DDU SCSI controller and floppy drive are working and I've ordered a
Seagate 40MB ST-506 drive to replace the failed Shugart drive.

I also noticed my new 4041 has a newer CPU board which includes the memory
on the CPU board and also only has four EPROMs!

The 4041 service manual indicates 4041 serial numbers B070100 and above
have this CPU board.

The service manual also indicates two of the EPROMs contain 128KB of
system ROMs - 28KB more than the earlier CPU boards. I believe the
additional 28KB is the UTL2 ROM only available for these CPU boards.

The service manual indicates the Option 10 for this CPU board is the two
additional 27256 EPROMs, which contain the R01 Graphics, R02 Plotting, R03
Signal Processing, R04 Utility1 option ROMs, which leaves room in the ROM
drawer for developer ROMs to be installed.

I ran the ASK$("ROMPACKS") command and got the list of all those option
ROMs and the UTL2.

I will capture the two Option EPROM images and post them on my 4041 github
repository sometime this weekend.