Re: Commodore PLC TIB DD-001 / Drive 2001

From: Ruud_at_Baltissen.org
Date: Thu, 29 Nov 2018 17:55:24 +0100
Message-ID: <5C0019FC.26183.1E7E0721@Ruud.Baltissen.org>
Hallo Spiro,


> 	cmp	#$E5			; ???

I found out later as well, see the subroutine Scratch.


> 	lda	(DirPointer),Y		; ???				[FB]

I simply forgot to remove it.

But thanks any way for your comment !!!


I still don't know if MS-DOS FAT12 is used. So far I haven't found 
any hard proof for it. What is quite disturbing is that the  program 
uses a lot of those "TapeBuffer+xx" variables. And some are used in 
more than one way. 

But the most important thing is that I understand how the FDC is 
programmed. The rest is a matter of using your own programmer's 
fantasy.
I'm familiar with handling FAT12; I started to write my own little 
OS. But later I started to use my own file system and parked it for 
the moment. If interested, I can send the sources so you can see how 
FAT 12 is handled.

I have three UM8397s laying around which only need two 7406 ICs plus 
a 4 Mhz oscilator to be able to function. That is, for a PC=XT. for 
any Commodore we need at least some thing to create the IOW and IOR 
signal from PHI2 and IOx. One halve of a 74LS139 would do. 

What could be done as well is to create a simple ISA bus interface, 
targeted on I/O only. And only trgetting the 3xxh range would mean 
that IMHO one halve of a 74LS139 is enough.


--
   
Kind regards / Met vriendelijke groet, Ruud Baltissen
www.Baltissen.org
Received on 2018-11-29 18:00:08

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