18 Nov
2005
18 Nov
'05
2:24 a.m.
Today I was hooking up my homebrewed driver board to the M-series
connector on the back of my Tally 420PR tape punch (interfaces to
my 8/A and . Fortunately, before I inserted the eight data pins
into the connector body it occurred to me that Tally and DEC might
not interpret the holes in the same order. And indeed they don't!
The paper tape has five holes on one side of the sprocket hole and
three on the other. Typical DEC terminology is Bit 1 = MSB and Bit
8 = LSB. Is that in fact how DEC labeled it?
Is the MSB on the outside of the 5-hole side or the 3-hole side?
Which hole on the tape is which?
Even more interestingly, Tally labels their punch pins as follows:
(* is the sprocket hole)
8 7 6 1 2 * 3 4 5
and I confirmed this by actual test. So much for consistency
<sigh>
-Charles
18 Nov
18 Nov
2:45 a.m.
Charles wrote:
Today I was hooking up my homebrewed driver board to
the M-series
connector on the back of my Tally 420PR tape punch (interfaces to
my 8/A and . Fortunately, before I inserted the eight data pins
into the connector body it occurred to me that Tally and DEC might
not interpret the holes in the same order. And indeed they don't!
The paper tape has five holes on one side of the sprocket hole and
three on the other. Typical DEC terminology is Bit 1 = MSB and Bit
8 = LSB. Is that in fact how DEC labeled it?
Is the MSB on the outside of the 5-hole side or the 3-hole side?
Which hole on the tape is which?
Even more interestingly, Tally labels their punch pins as follows:
(* is the sprocket hole)
8 7 6 1 2 * 3 4 5
For the pdp-8 tty punch/reader
channels 8 7 6 5 4 * 3 2 1
and I confirmed this by actual test. So much for
consistency
<sigh>
mind you as long as you only punch/read your own paper tapes does it
matter? :D
-Charles
4:49 p.m.
>>>> "Charles" == Charles
<charlesmorris at direcway.com> writes:
Charles> Today I was hooking up my homebrewed driver board to the
Charles> M-series connector on the back of my Tally 420PR tape punch
Charles> (interfaces to my 8/A and . Fortunately, before I inserted
Charles> the eight data pins into the connector body it occurred to
Charles> me that Tally and DEC might not interpret the holes in the
Charles> same order. And indeed they don't!
Charles> The paper tape has five holes on one side of the sprocket
Charles> hole and three on the other. Typical DEC terminology is Bit
Charles> 1 = MSB and Bit 8 = LSB. Is that in fact how DEC labeled it?
Charles> Is the MSB on the outside of the 5-hole side or the 3-hole
Charles> side? Which hole on the tape is which?
DEC PDP-11 era terminology is bit 0 is LSB, bit 15 is MSB. The PDP-10
numbering is the reverse (bit 0 MSB). The only one I can think of
that labeled the MSB bit 1 is IBM...
Anyway, in the usage I have seen, the paper tape rows are numbered
sequentially with the LSB at the outside edge of the 3-row side.
Certainly that's how it shows up in DEC PDP11 papertape interfaces (so
the outside edge 3-row hole translates to the LSB, bit 0, in the data
once it shows up in the CSRs or in memory).
paul
19 Nov
19 Nov
2:27 a.m.
Today I was hooking up my homebrewed driver board to the M-series
connector on the back of my Tally 420PR tape punch (interfaces to
my 8/A and . Fortunately, before I inserted the eight data pins
into the connector body it occurred to me that Tally and DEC might
not interpret the holes in the same order. And indeed they don't!
The paper tape has five holes on one side of the sprocket hole and
three on the other. Typical DEC terminology is Bit 1 = MSB and Bit
8 = LSB. Is that in fact how DEC labeled it?
Err, that depends on the DEC machine. My PDP11 has bit 0 as the LSB and
bit 15 asn the MSB. The PDP8/e on my desk has bit 0 as the MSB and bit
11 as the LSB . I don't know of any DEC machine that has bit 1 as the MSB
Is the MSB on the outside of the 5-hole side or the 3-hole side?
Which hole on the tape is which?
MSB LSB
7 6 5 4 3 * 2 1 0
Even more interestingly, Tally labels their punch pins as follows:
(* is the sprocket hole)
8 7 6 1 2 * 3 4 5
I have an idea that gets 1...5 right for 5-level baudot tape...
-tony
4:22 a.m.
Err, that depends on the DEC machine. My PDP11 has bit
0 as the LSB and
bit 15 asn the MSB. The PDP8/e on my desk has bit 0 as the MSB and bit
11 as the LSB . I don't know of any DEC machine that has bit 1 as the MSB
Actually I was referring to the labels within the PC8E schematic
where the punch lines are labeled "HOLE1" through "HOLE8". I agree
that bits should start at 0, and usually do...
As it turns out Hole 8..1 corresponds on a PDP-8 to data bits
4..11 respectively (more significant to least significant). I was
surprised since I expected the hole numbers to increase directly
with the data bit number.
I also found in the archives a copy of the manual DEC-08-NGCC-D
(PDP-8 Family Paper Tape Systems User's Guide) and on page 26/155
(manual page Intro-13) there is a nice diagram of the 8-bit tape.
So in conclusion the relationships on a PDP-8 are as follows:
Holes: 87654x321
Significance: MSB.......LSB
Data bus bits: D4.......D11
The punch is now hooked up (correctly) via my homebrewed driver
card to the PC8E interface, and merrily spews chad all over the
floor at high speed! I can email an Eagle schematic/board layout
for the drive card if anyone wants...
Now looking for a Tally 420 chad bucket :)
-Charles
20 Nov
20 Nov
12:48 a.m.
As it turns out Hole 8..1 corresponds on a PDP-8 to
data bits
4..11 respectively (more significant to least significant). I was
surprised since I expected the hole numbers to increase directly
with the data bit number.
That's exactly what I'd have expected. It puts the 'holes', in order, in
the low 8 bits of the machine word.
The punch is now hooked up (correctly) via my
homebrewed driver
card to the PC8E interface, and merrily spews chad all over the
Any chance of schematics being posted somewhere? I have a PC8e linked up
to my homebrew PC04 (well, converted from a PC05...). But I also have a
Tally 420, and I'd like to give it a go sometime.
floor at high speed! I can email an Eagle
schematic/board layout
for the drive card if anyone wants...
Please don't e-mail them to me. Can they go on a web page somewhere?
Now looking for a Tally 420 chad bucket :)
I have one, but it's not spare, if you see what I mean.
-tony
6985
days inactive
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ard＠p850ug1.demon.co.uk -
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