Re: Apple floppy adaptor. I'm stuck!

[Tristan Mumford <xtristan.xmumford@xgmail.xcom>]

Patrick Schaefer wrote:

> Tristan Mumford schrieb:
> 
>> What it can't seem to do is read and write. The basic question I want to
>> ask is whether the apple2 has an active high or low for read and write
>> pulses.
> 
> The Ehring FDC-4 controller uses two monoflops (1k-1nF) to generate
> Shugart WD and WG from Apple WData and WReq. I can send you a schematic
> of the card when interested.

I would be quite interested in seeing that if you don't mind :)
My e-mail is as stated in the header minus the 'x' characters and the "at"
and "dot"s correctly substituted.

> 
> 
>> I'm hoping I can get this issue sorted, because it's nearly done! I hope
>> I can get it working right, because I actually decided to use a
>> calculator to figure out final storage capacity *Gasp!*. A 2HD disk
>> should hold 640kb. In it's current form a normal 2HD disk appears as one
>> big single-sided 160 track disk.
> 
> As long as you use the Wozmachine as a modulator, 35 data tracks hold
> 140kB. It does not matter if you connect a 5,25", 3,5", 3" or 8" drive.
> To use the HD capacity, you would need twice the data rate from the
> controller. Commercial systems used a regular MFM controller like the
> WD2979 or µPD765 for these formats. Such a controller chip would allow
> CP/M and PC MSDOS compatibility.

Indeed. However, (140 / 35) * 160 = 640. I'm not overly sure if there would
be any difference whatsoever with a DD floppy.

Yeah, all original hardware on the controller. But after that it's my little
card then the PC floppy drive.

Thanks,

Tristan.
-- 
-----> http://members.dodo.com.au/~izabellion1/tristan/index.html <-----
=====       It's not pretty, it's not great, but it is mine.       =====