What would be Disk Parameter Block specs for 720K 3.5 " ???

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retrogear

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Nov 28, 2021, 10:42:18 AM11/28/21
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I've gotten Concurrent CP/M v3.1 bootable for an IBM compatible 3.5" 1.44MB
HD and have several requests for the 720K 3.5". What would be the DPB for those? I think the one I've found so far is for the 720K 5.25" quad density using John Elliot's chart here https://www.seasip.info/Cpm/cpm86form.html
Also what ID byte would it be ?

Larry G

retrogear

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Nov 28, 2021, 10:02:38 PM11/28/21
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Someone just shared a Personal CP/M-86 Teledisk image with me that is for a 720K 3.5". So it's the same format as 1.44MB HD except half the sectors/track.
80 tracks 2 sides 9x512 sectors/track. I converted it with TD02IMD utility to view the sectors and found the ID byte of the first sector = 11h so it is the DPB
in John Elliot's chart for 720K. I think I can make this work in my source code for Concurrent CP/M-86 3.1. I have new 800K 3.5" disks that I might be able to write it on. The 22DISK definition should
be easy enough.

ldkr...@gmail.com

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Nov 29, 2021, 9:24:01 PM11/29/21
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Larry,
Is this about the same as you came up with?
[code]
BEGIN COMF Compupro - DSQD 96 tpi 3.5" - 512 x 9
DENSITY MFM, HIGH
CYLINDERS 80 SIDES 2 SECTORS 9,512
SIDE1 0 1,3,5,2,4
SIDE2 1 1,3,5,2,4
ORDER SIDES
BSH 4 BLM 15 EXM 0 DSM 162 DRM 255 AL0 0F0H AL1 0 OFS 2
END
[/code]

I sent you an email.

Larry K.

retrogear

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Nov 30, 2021, 6:32:19 AM11/30/21
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DSM would be 354 or 162H. I don't even know if the sector order is linear or skewed.
I'm assuming linear. I don't have a formatter yet. I see in the PCPM image I have there is
a DSKMAINT.CMD. I need to see what that does. Work is keeping me busy at the moment.

Larry G

ldkr...@gmail.com

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Nov 30, 2021, 7:44:44 PM11/30/21
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22DISK can format if you have the Definition defined for the Image. Imagedisk ver 1.18
should also be able to format the floppy.

The 635_PCPM.IMD (635_PCPM.RAW) should work well with these Definitions:
[code]
BEGIN SIE3 Siemens PG-635 - DSDD 3.5"
DENSITY MFM, LOW
CYLINDERS 80 SIDES 2 SECTORS 9,512
SIDE1 0 1,2,3,4,5,6,7,8,9
SIDE2 1 1,2,3,4,5,6,7,8,9
ORDER SIDES
BSH 4 BLM 15 EXM 0 DSM 350 DRM 255 AL0 0F0H AL1 0 OFS 4
END

# SIE3 Siemens PG-635 - DSDD 3.5" - 512 x 9
diskdef sie3
seclen 512
tracks 160
sectrk 9
blocksize 2048
maxdir 256
skew 1
boottrk 4
os 2.2
end

# libdsk
[sie3]
description = SIE3 Siemens PG-635 - DSDD 3.5" - 512 x 9
sides = alt
cylinders = 160
heads = 2
secsize = 512
sectors = 9
secbase = 1
datarate = DD

# flashfloppy/GOTEK
[sie3]
cyls = 160
heads = 2
secs = 9
interleave = 1
bps = 512
id = 1
#rpm = 360
rpm = 300
rate = 250
mode = mfm
iam = no
[/code]


Larry


ldkr...@gmail.com

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Nov 30, 2021, 8:04:22 PM11/30/21
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libdsk's dskform can also format the Floppy.

[code]$ man dskform[/code]
[code]$ dskform --help[/code]
[code]$ dskform -type floppy -format sie3 /dev/fd0[/code]

Larry
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