After downloading DDBOOT1A.IMD and X820IICPM.IMD, I needed two new defintiions
for cpmtools and libdsk. IMDA & IMDU gave extra information on DDBOOT1A.IMD

$IMDA DDBOOT1A.IMD > DDBOOT1A.TXT

IMageDisk Analyzer 1.18 / Mar 12 2012
IMD 1.18: 24/01/2017 17:07:50

Required cylinders: 40
Required heads : 1
Data rate : 250kbps

Est. maximum track: 3919 bytes

$IMDU DDBOOT1A.IMD DDBOOT1A.RAW /B /E /D >> DDBOOT1A.TXT

IMageDisk Utility 1.18 / Mar 07 2012
IMD 1.18: 24/01/2017 17:07:50

Assuming 1:1 for Binary output
0/0 250 kbps SD 18x128
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
D D D D D D D D D D D D D D D D D D
1/0 D D D D D D D D D D D D D D D D D D

These Definitions should work:
# XER2 Xerox 820 - SSSD 48 tpi 5.25" - 128 x 18
diskdef xer2
seclen 128
tracks 40
sectrk 18
blocksize 1024
maxdir 32
skew 5
boottrk 3
os 2.2
end

# libdsk data below
[xer2]
description = XER2 Xerox 820 - SSSD 48 tpi 5.25" - 128 x 18
cylinders = 40
heads = 1
secsize = 128
sectors = 18
secbase = 1
datarate = SD

Code:
$ cpmls -f xer2 -D DDBOOT1A.RAW
     Name    Bytes   Recs  Attr     update             create
------------ ------ ------ ---- -----------------  -----------------
ASM     .COM     8K     64    
BB2CPM60.COM     9K     68    
BB2FORMT.COM     7K     51    
BIOS    .ASM    12K     96    
BIOS    .DOC     5K     34    
CBIOS   .ASM     9K     69    
CPM60   .COM     9K     68    
DDT     .COM     5K     38    
DEBLOCK .ASM    10K     80    
DISKDEF .LIB     7K     49    
DUMP    .ASM     1K      8    
   11 Files occupying     82K,       0K Free.
and CBIOS.ASM extracted properly:
Code:
$cpmcp -f xer2 DDBOOT1A.RAW 0:*.asm /home/larry/IMD-118/X820/

Which gave me yet another definition for X820IICPM.IMD:
;
;        fixed data tables for four-drive standard
;        IBM-compatible 8" disks
;        disk parameter header for disk 00
dpbase:        dw        trans,0000H
        dw        0000H,0000H
        dw        dirbf,dpblk
        dw        chk00,all00
;        disk parameter header for disk 01
        dw        trans,0000H
        dw        0000H,0000H
        dw        dirbf,dpblk
        dw        chk01,all01
;        disk parameter header for disk 02
        dw        trans,0000H
        dw        0000H,0000H
        dw        dirbf,dpblk
        dw        chk02,all02
;        disk parameter header for disk 03
        dw        trans,0000H
        dw        0000H,0000H
        dw        dirbf,dpblk
        dw        chk03,all03
;
;        sector translate vector
trans:        db        1,7,13,19        ;sectors 1,2,3,4
        db        25,5,11,17        ;sectors 5,6,7,8
        db        23,3,9,15        ;sectors 9,10,11,12
        db        21,2,8,14        ;sectors 13,14,15,16
        db        20,26,6,12        ;sectors 17,18,19,20
        db        18,24,4,10        ;sectors 21,22,23,24
        db        16,22                ;sectors 25,26
;
dpblk:        ;disk parameter block, common to all disks
        dw        26                ;sectors per track
        db        3                ;block shift factor
        db        7                ;block mask
        db        0                ;null mask
        dw        242                ;disk size-1
        dw        63                ;directory max
        db        192                ;alloc 0
        db        0                ;alloc 1
        dw        16                ;check size
        dw        2                ;track offset
;
;        end of fixed tables
;
$IMDU X820IICP.IMD X820IICP.RAW /B /E /D >> X820IICP.TXT

IMageDisk Utility 1.18 / Mar 07 2012
IMD 0.1: 29/07/2005 7:00:51

Xerox 820-II Boot

Assuming 1:1 for Binary output
0/0 500 kbps SD 26x128
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
D D D D D D D D D D D D D D D D D D D D D D D D D D
1/0 D D D D D D D D D D D D D D D D D D D D D D D D D D

BEGIN XER0 Xerox 820 - SSSD 48 tpi 5.25" - 128 x 26
DENSITY FM LOW
CYLINDERS 40 SIDES 1 SECTORS 26 128
SIDE1 0 1,7,13,19,25,5,11,17,23,3,9,15,21,2,8,14,20,26,6,1 2,18,24,4,10,16,22
BSH 3 BLM 7 EXM 0 DSM 242 DRM 63 AL0 0C0H AL1 0 OFS 2
END

# XER0 Xerox 820 - SSSD 48 tpi 5.25" - 128 x 26
diskdef xer0
seclen 128
tracks 40
sectrk 26
blocksize 1024
maxdir 64
skew 6
boottrk 2
os 2.2
end

# libdsk data below
[xer0]
description = XER0 Xerox 820 - SSSD 48 tpi 5.25" - 128 x 26
cylinders = 40
heads = 1
secsize = 128
sectors = 26
secbase = 1
datarate = SD

Code:
$ cpmls -f xer0 -D X820IICPM.RAW
     Name    Bytes   Recs  Attr     update             create
------------ ------ ------ ---- -----------------  -----------------
CONFIGUR.COM    12K     92 R  
COPY    .COM     5K     38    
DDT     .COM     5K     38 R  
DUMP    .COM     1K      4 R  
ED      .COM     7K     52 R  
HELP    .TXT    30K    235 R  
INIT    .COM     4K     28 R  
LOAD    .COM     2K     14 R  
MOVCPM  .COM    10K     76 R  
PIP     .COM     8K     58 R  
STAT    .COM     6K     41 R  
SUBMIT  .COM     2K     10 R  
SW      .COM    12K     92    
SWAP    .COM     1K      3 R  
SYSGEN  .COM     2K     11 R  
XSUB    .COM     1K      6 R  
   16 Files occupying    108K,      13K Free.
And the HxC Software created X820IICPM_IMD.SCP for the GreaseWeazle to write the SCP Image to a Samsung SFD-321B 3.5" floppy strapped for 360 RPM.

Larry