Accessing PCW discs on a CPC in CP/M

Accessing PCW discs on a CPC in CP/M

Post by Matthew Phillip » Sun, 13 Dec 1998 04:00:00



I have been having trouble for a while in trying to get my Amstrad CPC 464
running CP/M+ to read Amstrad PCW double-sided double-density 80 track
discs in the 3.5" B drive.  Actually, the reading is no problem, but when
writing the CPC seems to think that the 5th physical sector onwards are
not part of the directory (the 5th to 16th should be).  I have checked the
DPB, and I have set up AL0,AL1 correctly.

Has anyone succeeded in reading and writing to PCW 720k discs from CP/M+
running on a CPC?  I know it is easy to do for PCW 173k discs.

I am prepared to do some more investigation, and I have been looking
through the CP/M+ system guide from the CP/M web site.  In this it
mentions at one point that a banked CP/M+ system must use 2-bit allocation
vectors, rather than 1-bit.  As far as I can tell, the CPC implementation
is using 1-bit allocation vectors, yet is a banked system.  Any comments?!

In the mean time, back to the disassembler....

Matthew Phillips
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Accessing PCW discs on a CPC in CP/M

Post by John Ellio » Sun, 13 Dec 1998 04:00:00



>I have been having trouble for a while in trying to get my Amstrad CPC 464
>running CP/M+ to read Amstrad PCW double-sided double-density 80 track
>discs in the 3.5" B drive.

  I've heard that CP/M on the CPC needed patching to access double-track discs
such as the 720k PCW ones (so it could access the odd-numbered cylinders).
That's the only problem I've heard of.

Quote:>I am prepared to do some more investigation, and I have been looking
>through the CP/M+ system guide from the CP/M web site.  In this it
>mentions at one point that a banked CP/M+ system must use 2-bit allocation
>vectors, rather than 1-bit.  As far as I can tell, the CPC implementation
>is using 1-bit allocation vectors, yet is a banked system.  Any comments?!

  Don't know about "must". What's the double-bit flag set to in the
SCB?

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Accessing PCW discs on a CPC in CP/M

Post by Axel Berg » Mon, 14 Dec 1998 04:00:00


*John Elliott* wrote on Sat, 98-12-12 21:09 in comp.os.cpm:
JE>I've heard that CP/M on the CPC needed patching to access double-track
JE>discs such as the 720k PCW ones (so it could access the odd-numbered
JE>cylinders). That's the only problem I've heard of.

Yes, you would somehow need to tell the OS there is now 720 k of space
instead of just 180 k. But double stepping is only for reading 40 track
disks in an 80 track drive, just switching drives without telling the
CPC about it will make it use the outer 40 tracks of side 0.

Tsch? wa
                Axel

 
 
 

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I have got a PCW9512 disk with dbase on it.
I have 2 questions:
1st. Does anyone know if this copy of dbase will function on a CPC6128?
2nd. If so, how do I get it off the PCW disk to the CPC disk.

I have to admit I haven't actually got the PCW any more.
The disk is actually double sided but when I put it in my CPC I get:

CP/M Error on A: Invalid Drive
BDOS Function = 17 File = ????????.???

Some out there who has a PCW9512 and a CPC6128 would be ideal.

Here's hopin' - Stefan
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