[Coco] The COCO vs The Apple II

[RETRO Innovations]

On 1/11/2015 1:12 AM, didier derny wrote:
> The commodore serial bus was hell, it was designed for a hardware handshake
> But due to bugs in the hardware it was reverted at the latest minute to a software bit banging
>
> I think that one of the latest disk drive made by commodore uses the original hardware scheme planned
> (but only when connected to a C128).
>
> You have all the details in http://www.amazon.com/Commodore-Company-Edge-Brian-Bagnall/dp/0973864966/ref=sr_1_1?s=books&ie=UTF8&qid=1420960262&sr=1-1&keywords=commodore+a+company+on+the+edge

The tl;dr version is here:

ftp://www.zimmers.net/pub/cbm/faq/trivia/cbm-trivia-08.txt

question $07b

Jim's notes about the shift register have a few errors, but the gist is 
correct as written.

Bil Herd (who designed the C128) noted that one of the designers 
rerouted the 64 IEC lines to the correct spots on the 6526 to make fast 
disk work, but Japan saw the lines as redundant and so removed them 
during the last board rev before prod.

Oh well, most folks buy a disk speeder, which speeds up the disk 15X and 
makes things on par with other machines of the era.

Jim