SAB 82525
SAB 82526
SAF 82525
SAF 82526
Upgrades of HSCX Version V2.1
Version ID
3
The bits VN3 … VN0 of the Version Status Register (VSTR) contain the value 5 for version
V2.1. All HSCX version numbers are listed below:
VN3 … 0
0: 000
2: 010
4: 100
5: 101
Version
VA1
VA2
VA3
V2.1
4
RNR Flow Control in Auto-Mode
No more timing restrictions exist for HSCX V2.1 when the CPU accesses the RNR-bit of the
Command Register (CMDR).
5
I-Frames with P = 0 in NRM Auto-Mode
In multipoint configurations using the HDLC normal response mode (NRM) the P-bit of the
control field carries out the polling function. The primary station normally polls the other
secondary stations by transmitting either RR frames with P = 1 or I-frames with P = 1. I-frames
with P = 0 may be used by the primary station to transmit data to an individual secondary
station without requesting data from this station at the same time. In this case the secondary
station will receive and acknowledge this I-frame, but will not react by transmitting any data to
the primary station.
In the following it is assumed that the secondary station is waiting for transmission.
A secondary station using an HSCX VA3 in NRM auto-mode will transmit data to the primary
station after it has received an I-frame with of P = 0 or = 1.
The new HSCX V2.1 handles the P-Bit of I-frames according to ISO 4335. It will transmit data
to the primary station after it has received an I-frame with P = 1, but not after an I-frame has
been received with P = 0.
6
Transmission of Back-to-Back Frames
The new HSCX V2.1 supports back-to-back frame transmission in all clock modes without any
problem, including the strobe modes (clock mode 1 and 5).
7
INT Output Signal
The INT output signal of the HSCX V2.1 does not change its value during a write access to the
HSCX (CS x WR for Intel and DS x WR for Motorola).
Semiconductor Group
120
SIEMENS [ Siemens Semiconductor Group ]
