Anatomy of the 4040 Disk Drive (1988) | Hacker News Reader

Anatomy of the 4040 Disk Drive (1988)

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50 pointseaguyhn11 comments

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.

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

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

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_...

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

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

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...

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

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

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...

"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

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.

Winchester became widely used as an industry term outside of IBM for HDDs.

https://www.nytimes.com/1982/01/10/business/new-from-silicon...

I hadn't heard the Deskstar 50/50 term... most people I knew referred to them as either Deathstar or Deadstar.

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