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#108362 - 01/06/17 11:39 PM Re: Requirements? [Re: Bavarese]
Al Kossow Offline
Senior Member

Registered: 01/06/11
Posts: 144
Originally Posted By Bavarese


Time for new ventures... Corvus hard disks (of type B/H) are now working under CP/M 1.x...!

I admit, that's a bit old skool smile

Once upon a time Corvus supported MS-DOS 2.x and CP/M 2.2 too. But are there any driver disks left?


Al Kossow, to the rescue?


yea.. I have it somewhere. I have the manual sitting here too at least for Omninet support. Flat cable support should be somewhere, I worked with the guy who wrote the DOS driver at Corvus at Apple around 1987. I've got the CP/M driver on an 8" floppy

CP/M stuff is in bitsavers.org/bits/Corvus/Floppies/corvus1.tar



Edited by Al Kossow (01/07/17 12:35 AM)

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#108363 - 01/06/17 11:48 PM Re: Requirements? [Re: rfka01]
R. Belmont Offline

Very Senior Member

Registered: 03/17/01
Posts: 15435
Loc: USA
From a2corvus.cpp:

5 MB: -chs 144,4,20 -ss 512
10 MB: -chs 358,3,20 -ss 512
20 MB: -chs 388,5,20 -ss 512

Those were taken from Corvus technical documentation on Bitsavers.

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#108364 - 01/07/17 12:37 AM Re: Requirements? [Re: rfka01]
Bavarese Offline
Senior Member

Registered: 04/29/12
Posts: 140
Loc: Germany
Thanks. There is a bit of confusion around the hard disks used.

The CP/M 1 tools shown in the screenshot only mention the (larger, later) type H drives.

How did Corvus achieve 20 sectors on MFM drives, by the way?

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#108365 - 01/07/17 12:51 AM Re: Requirements? [Re: Bavarese]
Al Kossow Offline
Senior Member

Registered: 01/06/11
Posts: 144
Originally Posted By Bavarese
Thanks. There is a bit of confusion around the hard disks used.

The CP/M 1 tools shown in the screenshot only mention the (larger, later) type H drives.

How did Corvus achieve 20 sectors on MFM drives, by the way?


B drives used IMI 6 meg native flat cable drives
H drives are IMI 5006, 5012 or 5018 which are ST-412 and a formatter board

it is clocked at 11MHz

see corvus_mfm_decoder.c in Dave Gesswein's MFM emulator source for details of the sector format


Edited by Al Kossow (01/07/17 12:57 AM)

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#108366 - 01/07/17 01:01 AM Re: Requirements? [Re: R. Belmont]
Al Kossow Offline
Senior Member

Registered: 01/06/11
Posts: 144
Originally Posted By R. Belmont
From a2corvus.cpp:

5 MB: -chs 144,4,20 -ss 512
10 MB: -chs 358,3,20 -ss 512
20 MB: -chs 388,5,20 -ss 512

Those were taken from Corvus technical documentation on Bitsavers.


hm.. that doesn't look right. H drives had 1,2 or 3 platter drives in them. you're missing the 6mb H drive, they have 306 cyls, and 2, 4 or 6 heads.

-- ah the 10 and 20 are the 8" "A Drive" values

Board revision B detected
Found drive at select 1
Drive RPM 3596.0
Primary transition period 180 ns, should be around 200
Matches count 24 for controller Corvus_H
Header CRC: Polynomial 0x8005 length 16 initial value 0xffff
Number of heads 6 number of sectors 20 first sector 0
Interleave (not checked): 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Drive supports buffered seeks (ST412)

No sectors readable from cylinder 306
Stopping end of disk search due to two unreadable tracks in a row
Number of cylinders 306, 18.8 MB


Edited by Al Kossow (01/07/17 01:38 AM)

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#108367 - 01/07/17 09:57 AM Re: Requirements? [Re: rfka01]
Bavarese Offline
Senior Member

Registered: 04/29/12
Posts: 140
Loc: Germany
Yes, 306 cyls with 2, 4 or 6 heads are consistent with what i took from one of the many PDFs

Code:
Type H drives, used on the TRS 80-II and DEC Rainbow 100
6 MB :  -chs 306,2,20 -ss 512
11 MB:  -chs 306,4,20 -ss 512
20 MB:  -chs 306,6,20 -ss 512


I wasn't quite sure, given the 20 sector oddity...


Edited by Bavarese (01/07/17 09:59 AM)

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#108371 - 01/08/17 02:31 PM Re: Requirements? [Re: rfka01]
Bavarese Offline
Senior Member

Registered: 04/29/12
Posts: 140
Loc: Germany
Now that we emulate even exotic hardware from ancient times, i'd like to tackle long standing bugs smile

1. all hard disk boot loaders i tried crash our emulation (including, but not limited to latest WUTIL 3.2.x and DSKPREP).

It is possible to generate boot diskettes with DSKPREP for both MS-DOS and CP/M, yet neither 'autoboot' (from BIOS) nor a manual boot (W key) works correctly.

2. the ZFLIP flag or another Z80 register is wrong after CTRL/Setup (= standard method to warm boot the Rainbow)

I got some clues why 1. happens, and will report later smile


Edited by Bavarese (01/08/17 03:57 PM)

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#108483 - 01/18/17 05:39 PM Re: Requirements? [Re: rfka01]
Bavarese Offline
Senior Member

Registered: 04/29/12
Posts: 140
Loc: Germany
I have added info about 6 and 20 MB Corvus drives (and how to format / use them) under CP/M 86/80 version 1.

Al Kossow kindly provided driver source for Corvus on Lifeboat CPM 2.2, but this requires - more or less - skillful modification to work with DEC's CP/M 86/80 2.x.

There are wo obstacles: a specific patch address must be determined (RWMLOC & RWMDTA in old source from Maslin), and LDCOPY seems to be hard coded in version 2.x (will not write arbitrary loader files as in CPM 1). See HINSTALL.SUB:

(script from *, modifies 3 core CP/M 1.x files)
Code:
; CORVUS INSTALLATION DISKETTE IN A, CURRENT SYSTEM DISKETTE IN B
B:STAT B:*.SYS DIR
ERA B:Z80CCP.SYS
ERA B:Z80.SYS
ERA B:PRMTVPVT.SYS
B:PIP B:Z80CCP.SYS=A:HZ80CCP.SYS[V]
B:PIP B:Z80.SYS=A:HZ80.SYS[V]
B:PIP B:PRMTVPVT.SYS=A:HPRMTVPV.SYS[V]
B:STAT B:*.SYS SYS
B:LDCOPY A:HBOOT.LDR B:
; === THE DISKETTE IN DRIVE  B  HAS NOW BEEN CONFIGURED FOR USE WITH THE CORVUS DRIVE


Maybe one of the few remaining CP/M experts can have a look (Robert...)? smile
The TRS-80 variant uses the same type H drives, by the way...

http://www.retroarchive.org/maslin/disks/dec/
* http://www.retroarchive.org/maslin/disks/dec/drcdutil.zip
(Al Kossow's link, from Lifeboat CP/M 2.2):
bitsavers.org/bits/Corvus/Floppies/corvus1.tar


Edited by Bavarese (01/18/17 06:29 PM)

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