Re: Hard Drives for Apple //c+

[david@zircon.cs.uow.edu.au (David E A Wilson)]

ab616@cfn.cs.dal.ca (Tony Cianfaglione) writes:
>: >      The biggest setback with the IIc/IIc+ when it comes to hard drives 
>: > is the fact that ProDOS only recognizes 32 meg in each partition and 
>: > you're limited to 4 drives on the Smartport, not counting the 5.25 external.
>I use ProDOS 8- 2.3 on a IIc ROM 03 and a 1 meg card with a UniDisk and a 
>100 meg HD partitioned 3 segments. All I can get is 4 devices and then 
>something will get left off if I add a 4th partition. If the UniDisk 
>goes behind the drive, it vanishes. If the UniDisk is first, the 4th 
>segment vanishes. Ergo...4 devices. It's the reason why Sequential 
>doesn't sell a larger drive even though they said it would be cheaper per 
>meg to do so.  My system= Internal/S6D1, External/S6D2, CT1/S5D1, 
>CT2/S5D2, CT3/S2D2, UniDisk/S2D2, RAMDisk/S3D2.  S3D1, S4D1, S4D2 will 
>not access no matter how I switch things around. CT=Chinook Technologies.

Interesting. According to the Apple //c Technical Reference manual (2nd ed)
the following drive limits exist on //c computers:

(p84-6)			Int	Ext

//c	original	5.25	1x 5.25

//c	Unidisk		5.25	1x u3.5		1x 5.25

//c	memory exp	5.25	3x u3.5		1x 5.25

//c+			a3.5	1x a3.5		3x u3.5		2x 5.25

The //c mem exp has a maximum of 4 drives (int + ext).

The //c+ has a firmware/hardware limit of 5 drives (but only 4 should be used
due to power supply limitations).

(p210)
	The highest unit number supported by port 5 is $06 however due to
power supply limitations $04 is the highest that should be used.

This of course contradicts both the earlier reference and what Tony Cianfaglione
has determined by trial & error.

If anyone has the ROM listing for the memory expansion //c they may be able to
work out why the limit of 4 exists. I have the Unidisk //c ROM listing and
will have a look and see if it really only supports 1 UniDisk 3.5.