Hi all,
thanks, Chuck, for pointing to my website with the 604 drive, but
it's currently offline as I am required to update the disclaimer part.
This is required, since in Europe,a new law for data protection was
introduced on Friday, 25th of May.
I plan to put the website back online this week
11:27 AM
To: CCtalk
Subject: Whence 556?
List:
This is one that's bothered me for most of my adult life. As you may or may
not know, there were three industry standard densities for 7 track 1/2" tape:
200, 556 and finally 800 cpi/bpi.
So 200 and 800 are nice decimal multiples of 10.
On Tue, 5 Jun 2018, Chuck Guzis wrote:
And we're talking bits/chars per inch, so I don't see the connection,
particularly on a 75 ips drive.
Ehm, yes, I was thinking too fast and too simple... it's a hot day here.
Christian
On 06/05/2018 01:29 AM, Christian Corti via cctalk wrote:
> Just a guess, but 556 kHz is 5 MHz divided by 9.
Actually, it's a repeating decimal 555.
And we're talking bits/chars per inch, so I don't see the connection,
particularly on a 75 ips drive.
More guesses welcome! This one's b
On Sat, 2 Jun 2018, Chuck Guzis wrote:
So 200 and 800 are nice decimal multiples of 10. But 556 doesn't fit
that pattern--it's not a "nice' number, being the product of 4 and 139
and doesn't correspond to any computer-related characteristics that I
know of. It's not metric. So why 556 and not
On 06/04/2018 11:20 AM, Rich Alderson via cctalk wrote:
> For decades, I remembered the lowest density for magnetic tapes as 225
> bits/in,
> not 200. I have never been able to find the number "225" in any manual since
> starting the project which became the museum 15 years ago (sob!), but it st
From: Shoppa, Tim
Sent: Sunday, June 03, 2018 10:35 AM
> The 729 CE manual quotes 555 BPI. I’m not sure when it became 556.
> http://bitsavers.trailing-edge.com/pdf/ibm/magtape/729/223-6845_729_CEman_1959.pdf
> The IBM 728 was 248 BPI. Before that it was the nice round number 200 BPI.
> I tried
The 729 CE manual quotes 555 BPI. I’m not sure when it became 556.
http://bitsavers.trailing-edge.com/pdf/ibm/magtape/729/223-6845_729_CEman_1959.pdf
The IBM 728 was 248 BPI. Before that it was the nice round number 200 BPI.
I tried permutations of standard IPS and round number data rates and do
List:
This is one that's bothered me for most of my adult life. As you may or
may not know, there were three industry standard densities for 7 track
1/2" tape: 200, 556 and finally 800 cpi/bpi.
So 200 and 800 are nice decimal multiples of 10. But 556 doesn't fit
that pattern--it's not a "nice
