Buehring%ti-csl.csnet@CSNET-RELAY.ARPA (09/05/84)
From: Walt <Buehring%ti-csl.csnet@CSNET-RELAY.ARPA>
Just joined the list, so don't know if this is old news...
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Date: 1 Sep 1984 1608-CDT
From: SAENZ at TI-CSL
Subject: modem problems, Bunky?
To: buehring at TI-CSL
Found this in the 9/84 BYTE, p 34.
TIMING ERROR IN IIc MODEM ACKNOWLEDGED
The Apple IIc computer has a problem with many modems, an Apple
spokesperson has confirmed. Although insisting that both the 300
and 1200 bps Apple modems run on the IIc without problems, she
admitted that a timing error in the computer causes trouble for
some other modems.
The problem is the 6551 ACIA chip, which provides the clock for the
serial (modem) port, she said. This chip runs 2.9% slow; the specified
limits for modem-port clock speed are +- 2.0%. A highly knowledgeable
person at a major modem manufacturer -- not Apple -- said it is
extremely unlikely that any 1200-bps modem would be able to cope with the
IIc's speed variation ....
The apple spokesperson said that a quick fix for the problem is to set
7-bit word length, 1 stop bit and no parity (thus enabling ASCII but not
binary file transfers).
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Any other quick fixes? I just bought a //c and am having trouble
using my Racal-Vadic -- really need 8 data bits. Does Apple plan to fix
this?
/Walt/
Buehring%ti-csl@csnet-relay
-------john@hp-pcd.UUCP (john) (09/09/84)
The Sept 17 issue of InfoWorld (pg 63) also has a note about this problem. Someone found that the IIc will not work with either Hayes smartmodem or a Anchor Signalman at 1200 baud.Maybe the FTC will make them start advertising a 1165 Baud modem. John Eaton !hplabs!hp-pcd!john