kdj11-sd eproms

Douglas Taylor dj.taylor at starpower.net
Sat Mar 12 11:25:37 CST 2005

At 11:29 PM 3/5/2005, you wrote:
>I recently attempted to modify a decserver board
>to use the 11/53 roms.  I installed the pullup and
>burned the images into a pair of am27128A-2dc eproms,
>but when I powered up the board it couldn't pass test
>#1 with the "KDJ11-D/S 1.00" message.

I have successfully modified a DecServer board with the pullup resistor, 
but your experience sounds familiar to me.  It has been a while since I did 
this conversion but I seem to remember that there was a ROM contents 
checksum in the PDP11 boot and you had to burn the new rom completely to 
make sure all the locations were correct.

>I reverified the contents of the eproms and thought
>that I must've damaged the board when installing the
>pullup.  Just to be sure though, I remapped the 11/53
>images with "cat 261E5.bin 261E5.bin > 1.bin",
>"cat 262E5.bin 262E5.bin > 2.bin", then erased the
>original 27256's and burned the new images into them.

I think I tried this, burning two copies of the 128 ROM into the 256 ROM, 
and it didn't work without the pullup resistor.  I could be wrong since I 
am old (probably equal to the average age of people on this list) and MY 
memory may be failing!

>After reinstalling these I powered up, and the board
>came up okay:
>         9 8 7 6 5 4 3 2 1
>         Commands are Help, Boot, List, Map, Test and Wrap.
>         Type a command then press the RETURN key:
>So my question is, did I botch the pullup install
>or did I use the wrong eproms?  What eproms should
>work in the kdj11-sd?  The originals were am27256dc.
>My next step is to test a teac fd55gfr 149-u5 floppy
>drive for use as an rx33.  It appears to have the
>correct jumpers, but I haven't seen it listed as
>one known to work.  Can anyone confirm whether
>this model can be configured as an rx33?
>Eric Josephson

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