[Simh] RD53 image size

[Seth Morabito]

Hello all,

I'm trying to build an RD53 image that I can transfer to a real RD53
on an 11/73. I did the same with an RD52 on another system and it
worked perfectly, but I noticed something odd about the RD53.

The RD52 image size is 30,965,760 bytes. That maps exactly to 480
cylinders, 7 heads, 18 sectors/cylinder, 512 bytes per sector.
(480 * 7 * 18 * 512 = 30965760).

The RD53 image that SIMH generates, on the other hand, is 71,000,064
bytes. This does not match what I would expect. The RD53 is 1024
cylinders, 8 heads, 17 sectors/cylinder, 512 bytes per sector. That
should be 71,303,168 bytes, shouldn't it?

Is something wrong with my math, or one of my assumptions?

-Seth