Rich kids are into COBOL

Jon Elson elson at
Mon Mar 2 11:57:20 CST 2015

On 03/02/2015 12:19 AM, Mark Linimon wrote:
> On Sun, Mar 01, 2015 at 09:51:25PM -0600, Jon Elson wrote:
>> Yup, I tried to help bring up a surplus G-15D, but finally
>> discovered the drum was trashed.
> Too bad.  Was it physically dead, or just the bits scrambled?
The G-15 had a drum sectored off into short lines and long 
lines. the long lines
were the "main memory", the short lines were the register 
set.  Each line
had a write head, read head and an erase magnet, except for 
the clock
track, which only had a read head, and was recorded at the 

So, whenever you turned the machine off, the drum was 
erased.  The
sealing of the drum was REALLY bad, just an aluminum cover 
with a bundle
of wires fed through a hole with caterpillar grommet around 
the edge.
So, the drum area was FULL of dirt, and some had wedged 
against the heads
and scored several tracks.  At least one track was scored 
down to brass.

We tried writing data to the drum and reading it back, but 
got a lot of
garbage.  There were probably some bad tubes in the machine, 


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