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Re: MS2000 MicroDos Development System

Lee Hart
 

Stuart Remphrey wrote:
The number of times I saw people carrying 8" or 5.25" floppies out of
their jackets and with their sticky fingers all over the media; add to
that finding a few sticky write-protect/enable tabs sitting in those
older drives...
Here's a fun Christmas "hack" for us old-timers. I once had a pile of bad 5.25" floppies. So I wrote "Happy Holidays from Lee Hart" messages directly on the magnetic surface with a Sharpie pen (write a couple letters, rotate the disk a bit, write a couple more, etc.)

Then I put the address label and stamp directly on the naked disk, and MAILED it that way!

The post office delivered them, and furthered the joke by obligingly putting them in plastic bags that said something like "damaged in shipment".

PS: You have to know the people you are sending them to well enough to know they won't put them in a disk drive! :-)

Lee Hart

--
ICEs have the same problem as lightbulbs. Why innovate and make
better ones when the current ones burn out often enough to keep
you in business? -- Hunter Cressall
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

Re: MS2000 MicroDos Development System

ajparent1/kb1gmx
 

The 70 track drive may be readable on later 80 track drives but might require help to get
tracks to match up.   Someone that wants to might read the spec and do the work.

I'd go with plan C, one drive of oddball and another drive of the more modern form.
the FDC will not care and then you can get everything to a more common form
and with less gnashing of teeth.

AS to formatted capacity it was the 512 VS 256 or some case 1024 bytes sector and 
game like 8 sector of 512 vs 9 sectors by 512.  Since the 70track drives  do not have
the 10 tracks they are obviously smaller.

Re: Prototyping PCBs and Ipso Facto / ACE 1802 PCBs... #Electronics #IpsoFacto #Serial

ajparent1/kb1gmx
 

Interesting....

Tricks to make boards.

THe most common for one off is a cleaned piece of board and a Sharpie marker.
The ink in the marker is resistant to most etching solutions. Fast and cheap.

For years (many decades) a favorite for one off board is clear packing tape or
similar and usually 2" wide but can be found wider.   So packing tape and a
fresh Xacto knife blade and a while in ferric-chloride gets me a board.  Two
sided I use tape both sides.

The other uses sensitized board and a a light table with clear (acetate)
sheets with a printed pattern advantage is for small more than one to
maybe 10 boards works well and for two sided its more work but I've
found it good.

The latter technique can use used to scan and reproduce boards.

Re: Prototyping PCBs and Ipso Facto / ACE 1802 PCBs... #Electronics #IpsoFacto #Serial

Stuart Remphrey
 

On Tue, Apr 23, 2019 at 03:40 PM, Tom C wrote:
3. Original Tape-on-Mylar PCB Designs:
Hi Tom: just a thought, is it worth scanning those 2x tape-on-mylar/vellum designs and uploading somewhere? -- Stuart.

Re: MS2000 MicroDos Development System

Stuart Remphrey
 

Ooo, the Apricot, I'd forgotten those; we had a few in Oz IIRC (though of the fruit, I'd only used the Hitachi Peach 6809).

I do recall being pleased at the sliding media cover and write-protect "switch/tab": no more sticky write-protect/write-enable labels needed, yay!
The number of times I saw people carrying 8" or 5.25" floppies out of their jackets and with their sticky fingers all over the media; add to that finding a few sticky write-protect/enable tabs sitting in those older drives...

Still, I wouldn't mind something with an 8" drive for old-times sake (media must be getting mostly-past-it by now though?)

Re: MS2000 MicroDos Development System

Stuart Remphrey
 

Hmm, wondering about data interchange.
If I understand correctly: 70 tracks (vs 80) but still 135 TPI, with 125 micron track width and 63 micron blank guard band each side.

Was the recording density 3805 BPI (FM) and 7619 BPI (MFM) common between this drive and others? (maybe due to similar head geometry and media?)
It seems like it may be, with 160-vs-180 KB and 320-vs-360 KB formatted data capacity between these 70-track and the more common 80-track drives.

If so, while they had a 1/8 narrower recording area, nevertheless *if* track00 started at the same offset, could media written by one of these still be read by a "standard" 35-inch 80-track drive; and vice-versa if the last 10 tracks were usused?  (or not a snowballs or only on a good day with a tailwind?)

Re: MS2000 MicroDos Development System

cellarcat
 

Now that we know what drive was involved a search on Ebay and the net revealed a lot. These drives were used in the Sony SMC-70, the Apricot, the Dragon and HP 91-9200 dual disk drive units for the H-1B interface. I bought one of the Sony drives last night and it should be here next week. I will probably need to get another one as well since it appears that some of RCA's software expects two drives. I also discovered that the HxC floppy emulator can be programmed to replicate the Sony OA-D32. I have a HxC so that will be this weekend's project! 

On Dec 11, 2019, at 9:59 PM, ajparent1/kb1gmx wrote:

There was a short window where 3.5" and 3" floppies were both competing and trying
to dislodge the 5.25 floppies which were moving to half height and two sided and
what was called then quad density (80 cylinders, two sided, double density, about
800kb or so).  It came down to a battle between Teac and Sony, and then the clones.

That window was about '82ish to maybe '85.  By 1988 the microfloppy was standardized at
730K or 1440K.  There was the rare 2880K drives in the early 90s and they were not popular!

It was fun trying to figure what way to jump over the years for media and storage.

Re: MS2000 MicroDos Development System

ajparent1/kb1gmx
 

There was a short window where 3.5" and 3" floppies were both competing and trying
to dislodge the 5.25 floppies which were moving to half height and two sided and
what was called then quad density (80 cylinders, two sided, double density, about
800kb or so).  It came down to a battle between Teac and Sony, and then the clones.

That window was about '82ish to maybe '85.  By 1988 the microfloppy was standardized at
730K or 1440K.  There was the rare 2880K drives in the early 90s and they were not popular!

It was fun trying to figure what way to jump over the years for media and storage.

Re: MS2000 MicroDos Development System

cellarcat
 

600 rpm!  And the motor is turned on when the floppy is inserted. That answers some questions. It appears as well that the early 3.5 inch diskettes had covers that had to be manually slid over before the disc was inserted.


On Dec 11, 2019, at 9:52 AM, ajparent1/kb1gmx <kb1gmx@...> wrote:

That answers a lot of questions..
It does explain the microdos 70 track thing.

Had two of them given to me  back in the 80s and because they were incompatible
with other microfloppies I gave them away as mostly useless.  I'd nearly forgotten them.
It was around the time I was building up a SB180 (I still have) using microfloppies.

Re: MS2000 MicroDos Development System

ajparent1/kb1gmx
 

That answers a lot of questions..
It does explain the microdos 70 track thing.

Had two of them given to me  back in the 80s and because they were incompatible
with other microfloppies I gave them away as mostly useless.  I'd nearly forgotten them.
It was around the time I was building up a SB180 (I still have) using microfloppies.

Re: MS2000 MicroDos Development System

cellarcat
 

Outstanding! I looked all over the net for a reference to this drive. Thanks for the upload.


On Dec 10, 2019, at 10:28 PM, cmdrcosmac <cmdrcosmac@...> wrote:


Hi all,
I believe that this may have been the drive that RCA ran UT71/MicroDos with.
For your reading pleasure...
-Chuck
<Sony_Micro_Floppy_Disk_Drive_Model_0A-D30V_OEM_Manual_Mar82.pdf>

Re: MS2000 MicroDos Development System

cmdrcosmac
 


Hi all,
I believe that this may have been the drive that RCA ran UT71/MicroDos with.
For your reading pleasure...
-Chuck

Re: MS2000 MicroDos Development System

ajparent1/kb1gmx
 

Very good!

So far the most informative document and allows me to check asm against code.

Re: MS2000 MicroDos Development System

David Schultz
 

On 12/10/19 1:45 PM, ajparent1/kb1gmx wrote:
David,

IS the copy of MPM241 yu used for source the same as the copy at
BITSAVERS.org?
After scanning I provided a copy to bitsavers.


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Re: MS2000 MicroDos Development System

ajparent1/kb1gmx
 

David,

IS the copy of MPM241 yu used for source the same as the copy at BITSAVERS.org?

As in here:
http://bitsavers.trailing-edge.com/components/rca/cosmac/ms2000/MPM-241_RCA_MicroDisk_Development_System_MS2000_User_Manual_May84.pdf

Allison

Re: MS2000 MicroDos Development System

David Schultz
 

On 12/10/19 1:25 PM, ajparent1/kb1gmx wrote:
We have the clue that SYSGEN creates a disk and system (bootable) disks
have less user space.  Totally guessing, the track 0, sector 1 disk ID
has a lot
of free space and that has the system pointers to where the system is on
the
disk outside of the directory.
See TKTABL in UT71.

TKTABL DB 1,2,28 ;TABLE CONTAINS TRACK #. STARTING
DB 2,0,36 ;SECTOR # (-1). AND BYTE COUNT (X128)
DB 3,0,32 ;FOR ALL MICRODOS LOAD
DB 0

That is where the regular file OP.SYS should be. UT71 does a sanity
check (MICTST) after loading.

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Re: MS2000 MicroDos Development System

ajparent1/kb1gmx
 

after finding MPM241 in the complete form...

The ODS is a variant of the disk inode format from the days of V6 or 7ish
and ealry linux.

There is a:

Directory on track 00, disk sector 1 disk ID, sector 2-9 file directory

Track 1 sector 1, CAT which maps the used clusters (cluster=sector)
  1 bit per used sector 1=used.   allocation is LBA (not track sector).

Then the file start pointer sector is the SSN (start sector number) locating
the RIB.

The RIB is the mapping of used sectors (called SDW or segment descriptor)

That's a cut to the bone and minimal description.
Also applies to data only disks...

70 Tracks??
No clue why they only used 70 tracks, I suspect it was because the drives
looked like the oddball 100tpI (not 46, 96, or 135!) ones that appeared and
disappeared.  Or a religious thing back then being the inner tracks were
not generally good to use, likely because someone had issues with theirs.
The only mention of 70 tracks was infoworld in 1984 and the article got a
lot of critical attention being mostly wrong.

Gleaned from MPM241 page 89-92:
A small clue is that the OS uses about 4% of the space and apparently there
is an OS disk that has roughly 25Kbytes reserved (about 50 sectors or 5-6 tracks)
if we add that to the directory and CAT that 7-10 sectors used for "housekeeping".
We have the clue that SYSGEN creates a disk and system (bootable) disks
have less user space.  Totally guessing, the track 0, sector 1 disk ID has a lot
of free space and that has the system pointers to where the system is on the
disk outside of the directory.

So unless I unearth something its a mystery.

Allison

Re: MS2000 MicroDos Development System

cellarcat
 

This is from Appendix A in the MS2000 Manual:

Each diskette has 70 tracks with 9 sectors on each track (630 sectors per diskette). However, from MicroDOS's point ofview, the diskette is divided up into clusters with 1 sector in each cluster. The system diskette has two basic configurations, one with a directory and operating system and one with a directory only. These configurations are generated with the SYSGEN command. Because the operating system requires about 4 per cent of the diskette, diskettes with directory only have more disk area for storage of the user's work files. MicroDOS assumes that a me is a string of bytes. When a me is created, a certain number of clusters is allocated to it. If more space is needed for the data than initially allocated, MicroDOS automatically allocates more space. Once a me has been created by the user, the operating system returns to the system any unused disk cluster so that the next file to be created can use this freed-up space. No cluster can be allocated to two different files. 



On Dec 10, 2019, at 11:28 AM, ajparent1/kb1gmx wrote:

cellarcat,

That is one of the stranger drives.  All of the 3.5" drives I ahve (maybe 2 dozen or more) 
are either the early 40 track or later 80.  For that size i'd never seen 70 tracks.

For the 5.25size there was an oddball that tied to be a 77track (like 8") but tht was 
a rare beast.  Again there was a 5.25 that was two sided 35 cylinders (70 tracks).
However that was short lived and went to 40 cylinders to stay in line with
Sa400b/TM100 and others and the two sided versions SA450 were 40 cylinders
and two sided.  Same for the half height 5.25" drives like TEAC FD55 series
(both 40 or 80 track versions were both available in single sided and two sided).

Micropolus, Inovex has a few oddbals and there were the 3.0inch drives.
Most oall of those were extinct before they got traction.

What maybe the case is RCA used 10 tracks for system tracks or other hidden uses.
We can speculate....
An example of that is 8" SSSD (Single sided single density) was 77 tracks but the
first two (0 and 1) were reserved for the system and the directory and data were
stored on track 2 through 76 netting 75 usable tracks.  That practice was retained
even on CP/m on 1.44mb 3.5" floppies where two tracks would easily store the
system twice over.  Why?  Tradition!  No other good reason.  FYI the only reasonable
one I've heard is that keeping the directory off the outer track (000) was a bit more
robust but over time that proved unlikely.

FYI: I have not seen any information on the ODS (on disk structure) or organization
of how the tracks and sectors are used.   I could offer that MAYBE a far stretch the
first 10 tracks were boot tracks for the system (maybe 2-3tracks worth) and directory
for up to 80 files where each sector has a file name, details (meta), and allocated
spaces listed in that 512byte block. That's a wacky scheme but I've seen
many others.  Without the ODS information it is speculation.

So ODS?  Where did you get he Microdos 70track info?

Allison

Re: MS2000 MicroDos Development System

ajparent1/kb1gmx
 

cellarcat,

That is one of the stranger drives.  All of the 3.5" drives I ahve (maybe 2 dozen or more) 
are either the early 40 track or later 80.  For that size i'd never seen 70 tracks.

For the 5.25size there was an oddball that tied to be a 77track (like 8") but tht was 
a rare beast.  Again there was a 5.25 that was two sided 35 cylinders (70 tracks).
However that was short lived and went to 40 cylinders to stay in line with
Sa400b/TM100 and others and the two sided versions SA450 were 40 cylinders
and two sided.  Same for the half height 5.25" drives like TEAC FD55 series
(both 40 or 80 track versions were both available in single sided and two sided).

Micropolus, Inovex has a few oddbals and there were the 3.0inch drives.
Most oall of those were extinct before they got traction.

What maybe the case is RCA used 10 tracks for system tracks or other hidden uses.
We can speculate....
An example of that is 8" SSSD (Single sided single density) was 77 tracks but the
first two (0 and 1) were reserved for the system and the directory and data were
stored on track 2 through 76 netting 75 usable tracks.  That practice was retained
even on CP/m on 1.44mb 3.5" floppies where two tracks would easily store the
system twice over.  Why?  Tradition!  No other good reason.  FYI the only reasonable
one I've heard is that keeping the directory off the outer track (000) was a bit more
robust but over time that proved unlikely.

FYI: I have not seen any information on the ODS (on disk structure) or organization
of how the tracks and sectors are used.   I could offer that MAYBE a far stretch the
first 10 tracks were boot tracks for the system (maybe 2-3tracks worth) and directory
for up to 80 files where each sector has a file name, details (meta), and allocated
spaces listed in that 512byte block. That's a wacky scheme but I've seen
many others.  Without the ODS information it is speculation.

So ODS?  Where did you get he Microdos 70track info?

Allison

Re: MS2000 MicroDos Development System

cellarcat
 

Thanks, Dave! I think I will just fire up Linux and follow your instructions.

On Dec 9, 2019, at 6:26 PM, David Schultz <david.schultz@...> wrote:

On 12/8/19 11:51 PM, cellarcat wrote:
I should have looked more closely at the origins of the .img file. Dave
Schultz produced it and Dave, I assume, from reading your web page that
you used dd under Linux. I always thought dd and rawrite were similar
and could read each other's .img files but maybe not!
I have no idea what rawrite is looking for but that disk image is just
that, an image. It contains zero information on the disk geometry and is
just a linear collection of the disk sectors and tracks.


My notes say that this is how I read the data:

sudo ./setfdprm -p /dev/fd0 SS DD sect=9 cyl=80 ssize=512
sudo dd if=/dev/fd0 of=image bs=512 count=630




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