# How to find the amount of inter record gap in a magnatic tape?

1. Sep 9, 2011

### seini

hello i have a question given to me on a tutorial which is to find what is the largest IRG that will allow 80 percent of the tape to be data in 2400 foot magnetic tape has recording density 6400 Bpi and data records are 100 bytes and memory buffer is 10,000. i have been looking every where but i did not find any luck ...can someone help me with this question please

2. Sep 9, 2011

### Staff: Mentor

Welcome to the PF.

What kind of information does the tutorial give you before asking this question? There must be some context and useful information in the tutorial to help you answer this question, right?

3. Sep 9, 2011

### seini

well it suppose to be a tutorial but our lecturer said to go and do some research on it and the information that was given is the one i post it and our text did cover magnetic tape and i have been searching in the internet for it but it seem it does not really give me information on how to find it...

4. Sep 9, 2011

### Staff: Mentor

I could be missing something, but it looks to be just a straight math problem. You are given the data density in Bytes per inch (is that what Bpi stands for?), and you are given the amount of data and the length of the tape. You want the data to end up being 80% of the tape, so how big can the gaps be?

Try just working it as a math problem using the numbers you are given. Show us your work, so we can see if it seems you are on the right path.

5. Sep 10, 2011

### AlephZero

I think that's right, because this is back-to-front compared with how the format of real mag tape used to work. The inter-record gap was a fixed size, long enough (usually a few mm) to allow the tape to stop and start between records. The thing you could change was the data record (block) length, not the gap length.