17 Jun
2023
17 Jun
'23
7:57 p.m.
I finally got an IBM 5120 earlier this month, to complement the 5100 and
5110 that I already have.
It had a few issues, but I did manage to get it to "boot" to BASIC.
I put together a few notes about it here. Nothing too exciting, but two
things I've learned: (1) the 5120 does actually still have the video
REVERSE feature. (2) the 5120 has both an external (red power switch) and
internal power switch (internal one is at rear below disk drives).
Notes here:
https://voidstar.blog/ibm-5120-aka-ibm-5110-3/
IBM 5120 (aka IBM 5110-3) — voidstar
<https://voidstar.blog/ibm-5120-aka-ibm-5110-3/>
My only question is: how "universal" are 8" disk? This 5120 only came
with
a single IBM 8" Diagnostics disk. It looks to be in fine condition, but
I've no idea about the data.
So far I haven't been able to read it - it's probably more hardware/drive
issues, I'm still investigating. But I'm wondering if I had other 8"
disks (3M SS/SD), should I be able to format/MARK them?
I've used old tape decks and 5.25" drives - but 8" drives is all new
territory for me.
Also, I'll be talking about the 5100/5110 at VCF next Sunday on the 25th of
this month, June.
17 Jun
17 Jun
9:03 p.m.
On Sat, 17 Jun 2023, Steve Lewis via cctalk wrote:
I finally got an IBM 5120 earlier this month, to
complement the 5100 and
5110 that I already have.
. . .
My only question is: how "universal" are 8" disk? This 5120 only came
with
a single IBM 8" Diagnostics disk. It looks to be in fine condition, but
I've no idea about the data.
So far I haven't been able to read it - it's probably more hardware/drive
issues, I'm still investigating. But I'm wondering if I had other 8"
disks (3M SS/SD), should I be able to format/MARK them?
I've used old tape decks and 5.25" drives - but 8" drives is all new
territory for me.
I do not know anything about 5120.
But, several sources mention the drives as being 1.2M
That would be double sided, double density.
Are you sure that you want SS/SD?
One article mentioned 256 bytes per sector, which would be consistent with
double density, as single density 8" was usually 128 bytes per sector.
You can usually get away with formatting a SD (FM) disk as DD (MFM), but
SS and DS 8 inch are different!
A few quick things about 8", (which you are likely to already know)
1) write protect is opposite of the way 5.25" does it; an open notch is
write protected, you need to cover the write protect notch if you want to
write.
2) single sided and double sided 8" disks have the index hole in the
jacket in different places. Therefore, they are not fully
interchangeable.
single sided disks will often have a "1" on them; double sided sometimes
have a "2"
"1D" and "2D" are single and double sided, double density.
Some drives have two sets of index sensors, to be able to handle both
single and double sided; some do not.
Punching additional holes in the jacket does work to convert one to the
other, which ends up looking a lot like the index holes for the
hard-sectored disks.
http://www.bitsavers.org/pdf/3M/3M_Diskette_Reference_Manual_May83.pdf
figure 3 shows the locations of the index holes
With a SS and a DS side by side, it's obvious; if you don't have both, . . .
If you imagine a line along the read/write slot, and a line from the
center of the hub hole, the SS is at a 7 degree angle, and the DS is at a
26 degree angle
--
Grumpy Ol' Fred cisin(a)xenosoft.com
9:17 p.m.
1) write protect is opposite of the way 5.25"
does it; an open notch is write
protected, you need to cover the write protect notch if you want to write.
If I remember correctly, in the 1994 "Computer Bowl", Bil Gates' team was
unable to answer the question about where the write protect notch is on an
8" disk. It is on the front edge of the disk. That helps 8" disks to
leave loose write enable tabs that fall off where they can do more damage.
19 Jun
19 Jun
8:38 a.m.
On Sat, 17 Jun 2023, Steve Lewis wrote:
My only question is: how "universal" are
8" disk? This 5120 only came with
a single IBM 8" Diagnostics disk. It looks to be in fine condition, but
I've no idea about the data.
I can answer your question very quickly:
A 5120 is exactly the same as a 5110 plus 5114. This said, the diagnostics
and any software apply to both systems.
You can take any 5110 floppy image and recreate a real floppy from it. The
format BTW is "the" standard IBM format. The 5114/5120 can handle
everything from single-sided single-density up to double-sided
double-density. The firmware OTOH has a predefined set called "formats",
ranging from 1 to 9, with an optional suffix indicating the number of
additional directory tracks (only available with DD). The list is
somewhere in the manual, e.g. format 1 is SS/SD 128 bytes/sect. 26
sects/track, and format 8b (b=blank) is DS/DD 512 bytes/sect. 15
sects/track.
IIRC format 1-3 are SS/SD, 4-6 SS/DD and 7-9 DS/DD
Christian
1 Jul
1 Jul
6:21 a.m.
Ok, so I grabbed some DS/DD 3M 8" disks - I assume I can "MARK" them
(reformat). But so far no luck. I never had disks on the 5110, so still
learning about them on the 5120 - I assume they still need to be "MARK"
just like the tapes are?
Here is a short video I made of the 5120 disk drives I have during startup
of the system. I'll double check the fuses of the system tomorrow - the
fuse behind the CRT was blown, so I'm thinking it's possible this system
had some other electrical problems.
IBM 5120 Disk Drive Example (benchtop experiment) - YouTube
<https://www.youtube.com/watch?v=UxyDDx8LOGw>
https://www.youtube.com/watch?v=UxyDDx8LOGw
Much to investigate, but so many other projects - I may need to just put
away these 8" drives for a while.
OH, and I finally got to talk about the 5100 series. I'm not the best
speaker and a couple mistakes I noticed - but mostly I hope I didn't
horribly misrepresent your prior work.
https://www.youtube.com/watch?v=JIJNrBaTenM
-Steve
On Mon, Jun 19, 2023 at 3:38 AM Christian Corti via cctalk <
cctalk(a)classiccmp.org> wrote:
On Sat, 17 Jun 2023, Steve Lewis wrote:
My only question is: how "universal"
are 8" disk? This 5120 only came
with
a single IBM 8" Diagnostics disk. It looks
to be in fine condition, but
I've no idea about the data.
I can answer your question very quickly:
A 5120 is exactly the same as a 5110 plus 5114. This said, the diagnostics
and any software apply to both systems.
You can take any 5110 floppy image and recreate a real floppy from it. The
format BTW is "the" standard IBM format. The 5114/5120 can handle
everything from single-sided single-density up to double-sided
double-density. The firmware OTOH has a predefined set called "formats",
ranging from 1 to 9, with an optional suffix indicating the number of
additional directory tracks (only available with DD). The list is
somewhere in the manual, e.g. format 1 is SS/SD 128 bytes/sect. 26
sects/track, and format 8b (b=blank) is DS/DD 512 bytes/sect. 15
sects/track.
IIRC format 1-3 are SS/SD, 4-6 SS/DD and 7-9 DS/DD
Christian
1:18 p.m.
On Sat, 1 Jul 2023, Steve Lewis wrote:
Ok, so I grabbed some DS/DD 3M 8" disks - I
assume I can "MARK" them
(reformat). But so far no luck. I never had disks on the 5110, so still
learning about them on the 5120 - I assume they still need to be "MARK"
just like the tapes are?
You must lowlevel format them first. There's a utility (on the Utilities
disk) called INITIAL to do this. You will have to choose the layout and
density, i.e. format 1-9 and, if applicable, how many extra directory
tracks (only on DD disks). Only then you will be able to mark them.
OH, and I finally got to talk about the 5100 series.
I'm not the best
speaker and a couple mistakes I noticed - but mostly I hope I didn't
horribly misrepresent your prior work.
https://www.youtube.com/watch?v=JIJNrBaTenM
+1 :-)
Christian
511
days inactive
525
days old
5 comments
3 participants
participants (3)
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Christian Corti -
Fred Cisin -
Steve Lewis