20 Sep
2013
20 Sep
'13
4:34 p.m.
On 21/09/2013 00:06, Chuck Guzis wrote:
On 09/20/2013 02:27 PM, Dave wrote:
I think the S/360 and S/370 reader/punch machines read by row, e.g. the
2540
http://bitsavers.informatik.uni-stuttgart.de/pdf/ibm/25xx/A21-9033-1_2540_C…
and oddly when reading 51-Column cards it stored the data in the middle
(Cols 15-65) of the buffer (see page 9)
but certainty the 1130 high speed reader read by column, and I believe
that it was supplied with a small toggle that caught the cards and made
them stack taped away in an ineffective position. As a result it would
spew cards across the room if not properley installed....
The only readers I have seen that read row binary
were IBM but I said
"some" as I didn't know if they were the only readers that worked that
way. It seems obvious it should be faster that way so I have in the past
wondered if IBM had a patent on reading by the row...
Yup, the card reader on the 704 read cards starting with the nine's
row, storing right and left sides into 26-bit words. Now you know why
FORTRAN reserved the last 8 columns for a sequence number--the 704
couldn't read them! The 1402 reader, read column-wise and I believe
all subsequent IBM readers did also.
A quick check in my library says that the
"short" cards were 51
column, not 40. I haven't the faintest idea of what or why that
particular format came about. Perhaps something like perforated
inventory cards, where a part of the card could be torn off and used
as a printed record?
Anyone know for certain what the 51-column card was for?
I think the card just grew over the years..
--Chuck
Dave