Interest in Teac FD235J drives and FC-1 boards?

Glen Slick glen.slick at
Wed Jan 24 16:35:25 CST 2018

On Wed, Jan 24, 2018 at 9:45 AM, Fred Cisin via cctalk
<cctalk at> wrote:
> Does ImageDisk or Teledisk support it?
> If so, then with the ED controller and one of these drives from Chuck, you
> could image things such as the "4 Meg" floppies from NeXT. (4M is the
> UNFORMATTED capacity of the 2.8M disk, and NeXT marketing thought that "4M"
> sounded better than the "2.8M" formatted capacity)

The ImageDisk 1.18 source code is available to inspect to answer the question.

If there is something special that software needs to do to select a
1000K bps data rate I don't see anything in the ImageDisk code which
does that. What does software need to do to select the 1000K bps data
rate for 2.8M mode?


unsigned Mtext[] = { // Translate Mode%3 to actual data rate
500, 300, 250 };

 * Initialize data transfer mode (rate and density)
 * and update status display.
void initmode(void)
unsigned x;
Mfm = (Mode / 3) ? 0x40 : 0x00;
out(FDC+5, x = Mode % 3);
w_gotoxy(3, 0, swin);
w_printf(swin, "%3uk %cD", Mtext[x], Mfm ? 'D' : 'S');

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