DATE: July 29, 1982
REVISION DATE: September 8, 1986
BULLETIN NO: II:33
PRODUCT: 26-4001/2 Model II 26-6001/2 Model 16
SUBASSEMBLY: AXX-0501 Z-80 CPU AX-9242 Z-80 CPU
SUBASSEMBLY REVISION:    All Revisions (Rev. A,B,C,&D)
PURPOSE: Checksums for Model II/16 Boot ROM's.
 
   DISCUSSION: The  following checksum values are for the boot ROM (U11) on the
  Z-80 CPU board in both the Model II and Model 16 using MEMII.
1. 432F Boots floppy drives only. (Early Model II's only)
2. 0A79 Boots floppy drives only.
3. 4A6A Hard drive boot ROM. (Installed with hard drive upgrade)
4. 88E2 or F42A
Also Hard drive boot ROM. These two ROM's have a slightly
different boot sequence. The ROM checks for track 00
indication, if the head is on track 00 it will be stepped
out and then back in before reading the boot track. This is
because the Tandon drive does not have a track 00 stop, and
it is possible for the head to fall out beyond track 00 and
still give a track 00 indication.
5. C9AC or E996
These checksums will be found in Model 12/16B/6000's
normally, but will also be found in newer Hard Drive Upgrade
kits. These checksums are compatible with Western Digital
hard drive controllers The E996 checksum will usually
only be found in machines with internal Hard Drives. Both
checksums are backward compatible which means they will work
with all current Hard Drives.