Date   : Tue, 31 Jul 2007 03:46:34 -0700 (PDT)
From   : cjl_craves@... (Peter Craven)
Subject: [BBC Micro] Coprocessor/ Tube Use

1. a) Can a program in the Coprocessor (client/ parasite) transfer data 
from the host to the parasite, or does the program have to reside in the
host? The examples in the Acorn Support Group Application Notes and other
places I have read always give the example program as existing in the host....

b) How would the example program from the ACorn Support Group Application
Notes be changed to reside in the parasite and transfer H-->P??

CLAIM LDAIM &CO+&10 ; Say my ID is 16
JSR &0406 ; Claim the Tube
BCC CLAIM
LDXIM &00 ; Lo byte of &3000
LDYIM &30 ; Hi byte of &3000
LDAIM 6 ; P -> H, 256 bytes
JSR &0406
JSR ANRTS ; 6 uS delay
JSR ANRTS ; 12 uS delay
JSR ANRTS ; 18 uS delay
LDYIM 0 ; so the initial delay in 19 uS
LOOP LDA &FEE5 ; Get it from the port ( 2 uS = 2)
STAIY &80 ; Put the data byte (+3 uS = 5)
NOP ; (+1 uS = 6)
NOP ; (+1 uS = 7)
NOP ; (+1 uS = 8)
INY ; (+1 uS = 9)
BNE LOOP ; Next data byte (+1.5 uS = 10.5 uS/byte)
LDAIM &80+&10 ; Release code + My ID
JSR &0406 ; Release the Tube

2. These same documents I have read also mention that BPUT for large amounts
of data transfer.....

"Moving large quantities of data: To move large quantities of data, for example
a complete screen update,
the fast Tube BPUT OSBYTE call is used. Prior to the call, some machine code
is placed in the I/O
processor ready to handle the data as it arrives across the Tube from the
co-processor. When data is ready
to be moved across the Tube, an OSBYTE &9D (157) is made to initiate the
users code to in the I/O
processor. The data is moved through Tube register 1 and handled by the user
code on the other side. Note
that all OSBYTE calls are vectored through the BYTEV vector at &20A,B in
the I/O processor, and this
vector has to be intercepted to detect an OSBYTE &9D call and pick up the
X and Y parameters to be used
by the user's code. The advantage of OSBYTE &9D over other OSBYTE calls is
that after the X and Y
parameters have been sent across the Tube, control is immediately returned
to the parasite. no parameters
are returned."
 
Could anyone please elaborate and possibly give small example program?

Thanks

Peter


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