<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body ><div>Probably a reasonable solution at the rime. Who would ecer be able to fill up such a llarge disk?</div><div><br></div><br><br><br>-------- Original message --------<br>From Bob Supnik <bob@supnik.org> <br>Date: 02/27/2016 11:45 AM (GMT-07:00) <br>To simh@trailing-edge.com <br>Subject [Simh] Unix v0 disk is an RB09 or equivalent <br> <br><br>I've gone through the disk IO routines line by line, with this result: <br>while Unix confines reads and writes to blocks <= 79999, it maps those <br>blocks to the SECOND 512KW of the the disk. See the attached analysis. <br>So the Unix v0 disk is an RB09 equivalent, and the RC09 on the field <br>service listings is probably an RB09. The reason for the different names <br>remains unexplained. (The drive was made by Burroughs - thanks to Tim <br>Litt for finding the reference.)<br><br>dsksav copies side 1 to side 0, and dskres does the reverse, so side 0 <br>was used as a backup for the main disk image: handy if a programming <br>experiment wrecked the disk image.<br><br>/Bob Supnik<br><br>_______________________________________________<br>Simh mailing list<br>Simh@trailing-edge.com<br>http://mailman.trailing-edge.com/mailman/listinfo/simh</body>