[Info-vax] wrong file format

[Arne Vajhøj]

On 1/3/2021 3:13 PM, Hein RMS van den Heuvel wrote:
> On Saturday, January 2, 2021 at 11:01:12 PM UTC-5, Craig A. Berry wrote:
>> On 1/2/21 8:04 PM, Arne Vajhøj wrote:
>>> On 12/31/2020 10:54 PM, Bill Gunshannon wrote:
> 
>>> * the traditional story is that all language RTL IO goes
>>> through RMS - including C RTL (even though that one
>>> supposedly is a bit more complicated than other
>>> languages)
> 
> Last century, yes.
> Today for the simple sequential file COBRTL, CRTL and SORT switched away from record IO to roll their own with BlockIO ($READ, $WRITE).
> I don't recall them doing direct $QIO calls. BlockIO is a tiny layer over QIO adding error handling mostly.
> Record IO is way to expensive for high volume IO - going in and out of exec mode 'all the time', probing the argument blocks and buffers and so on.
> Block IO incurs this overhead typically much less frequently to the point where it does not really matter ( 10 ...  50 times less is my guess).

Block IO is still RMS.

But a lot more DIY.

Besides the error handling doesn't $WRITE also handle stuff like
extending the file? ($QIOW WRITEVBLK does not).

Arne