
Anatomy of the 4040 Disk Drive (1988) - eaguyhn
https://www.pagetable.com/docs/anatomy-4040.html
======
localhost
During school summer holidays back in the day at Richvale Telecommunications,
I and a few of my friends there, including a guy named Troy Hacker (not making
this up!) spent most of a summer reverse engineering the "OS" for the 4040 and
8050 disk drives.

The 6504/6502 pairing in the drive with the 6504 handling disk controller
operations and the 6502 handling IEEE 488 bus communications was ...
interesting. Especially later on when Commodore created the 1541, where they
emulated the functionality of the original 4040 design by doing everything via
software on a single 6502, including the GCR decoding step which was handled
by a dedicated ROM in the 4040 - all presumably to drive down the cost of the
drive.

Since we didn't have a memory map of the drive (and certainly no easy way to
debug code running on it) we had to read the boot code to figure out what it
did and construct our own memory map from that. I still remember the moment
when my 13 year old self realized that the code I was reading was blinking the
drive LED lights as part of the POST test and then figuring out what the
different error codes that I had never seen before were. Good times.

------
tyingq
Interesting that the drive has 2 65xx processors, so it's twice as powerful as
the PET computer using it.

~~~
myrandomcomment
Commodore owned MOS so it was cheap for them. The PET and the other commodores
did not have any code (beyond sending messages to the bus) for the drive, or
anything else. The bus devices where thus generally intelligent. I have an old
8050 drive on the shelf here (another version of this drive).

[https://en.m.wikipedia.org/wiki/Commodore_8050](https://en.m.wikipedia.org/wiki/Commodore_8050)

The most amazing thing is how heavy it is. All folded steal. 28lbs, 13kg!

Also the size of the caps in it is amazing.

[https://farm6.static.flickr.com/5316/14028063048_1ae4c72023_...](https://farm6.static.flickr.com/5316/14028063048_1ae4c72023_b.jpg)

I have not powered it up in years. I might try to get an old PET on eBay and
get it all working again.

~~~
jacobush
There are ways to connect C64 drives to a PC and other modern things, so maybe
you can go that or similar route

~~~
myrandomcomment
I have the IEC (VIC20 bus) to parallel port cable from a few (10) years ago
that I used to use to use under DOS to write images to my 1541. The 8050 and
PET stuff is IEEE-488 connectors. I think I even have a C64 user port to
IEEE-448 adapter. I have 4 C64 in various state of repair here that I am
pulling apart to put in the C64 Reloaded MK2. The biggest issue is time. I
have had the dang thing for 6 months now. I also have 2 x C128 I am trying to
make a single working one from. I have replaced a number of the ROMs but still
having issues. Need to desolder and replace the RAM now as that seems to be
failing. I have a stacks of unopened 5-1/4 disk and boxed games. Issues is
always time :)

[https://icomp.de/shop-icomp/en/produkt-
details/product/c64-r...](https://icomp.de/shop-icomp/en/produkt-
details/product/c64-reloaded-mk2.html)

One of the biggest things now is you can get is an IEC to compact flash. Looks
like a 1541 to the C64.

~~~
jacobush
Yeah... we have only one life. Gotta do the important stuff and not fill it
with _only_ distractions.

------
myself248
Not to be confused with the Winchester "30 30" disk drive, which was a hard
disk pack, or the Deskstar "50/50" drive, which refers to the likelihood of
getting data back off the thing...

~~~
tyingq
"Winchester 30 30" is pretty curious branding for a disk drive. For most
people, that's a popular ammunition type for a lever action rifle:
[https://en.m.wikipedia.org/wiki/.30-30_Winchester](https://en.m.wikipedia.org/wiki/.30-30_Winchester)

~~~
myself248
Yup, it was officially the "IBM 3340 Direct Access Storage Facility", but it
was designed to have two 30-meg disk packs, so internally everyone called it
the "30 30", and owing to the rifle, the project became codenamed Winchester.
Strictly unofficial, but ubiquitous in certain circles.

The product actually shipped with either 35 or 70 meg disks, so it was an
immediate misnomer, but the name stuck anyway. You'll find references to it in
old mainframe texts.

