SHARP PC-G850V(S) User Manual -
Appendix A: 11-Pin Interface
13
This is the signal-semantics within the CE-126P tape protocol:
Pin
#
Signal
Direction Semantics
4
BUSY
Out
Clock pulse for synchronous, serial handshake
5
DOUT
Out
Data line for handshake
6
XIN
In
PWM data from the cassette interface (load)
7
XOUT
Out
Handshake: See CE-126P printer protocol
Data: PWM transfer to the cassette interface (save)
8
DIN
In
No function
9
ACK
In
CE-126P ready to receive data or commands
(handshake)
The following diagram shows the signal timing of the CE-126P tape protocol for a
BSAVE-operation (saving a BASIC-program with only one line):
The dynamics for a BLOAD-operation is equivalent, but the PWM-data is received
through the XIN-signal then.
PWM-Mode: Generic PWM-Protocol
This protocol is equal to the CE-126P tape protocol reduced to XOUT and XIN. It is
activated by the commands BSAVE, BSAVEM, BLOAD, BLOADM, BLOAD? when
no
CE-126P (or compatible cassette interface) is connected. Typically this would be the
case, if two PC-G850V(S) are directly interconnected by a cross-wired cable like the EA-
129C. The PC-G850V(S) distinguishes the activation of the CE-126P tape protocol from
the generic PWM protocol by setting XOUT to HIGH as the very first action for a
BSAVE/BLOAD-command: If ACK is
not
going HIGH then, the generic PWM-protocol is
used (i.e. BUSY/DOUT/ ACK handshake being skipped).
