Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!pyramid!voder!wlbr!pete
From: pete@wlbr.EATON.COM (Pete Lyall)
Newsgroups: comp.sys.m6809
Subject: Re: RS-232 Program Pak Problems
Message-ID: <1173@wlbr.EATON.COM>
Date: 1 Feb 88 18:59:27 GMT
References: <1017@cblpf.ATT.COM>
Reply-To: pete@wlbr.UUCP (0000-Pete Lyall)
Distribution: na
Organization: Eaton IMS, Westlake Village, CA
Lines: 42
Keywords: Program Pak Coco3

In article <1017@cblpf.ATT.COM> mdk1@cblpf.ATT.COM (41450-Michael King) writes:
>
>I have been having problems with my Radio Shack RS-232 Program Pak.....

Mike - 

The RS-232 pak under LII has problems with dropped interrupts. This is
primarily because of the GIME, and the way interrupts are managed
(edge vice level sensing is employed). Many/most folks have gotten
around this by running a PHYSICAL IRQ jumper out of the pak and into
the CPU.

You find the little blue jumper wire that currently connects to pin 8
on the RS-232 pak.. it connects to a point about 1/4" to the left.
Remove this jumper, and connect a wire to what was the left connection
point. Run this out the side of the pak, and connect a plug to it (I
use a subminiature phone plug). On the coco end, connect a line to the
CPU's IRQ pin (pin 3). The easiest place to do this is on the pull up
resistor for the IRQ line... I believe it's R2, but I'm not near a
coco or schematic at the moment. Best bet is to check with an ohm
meter from PIN 3 of the 6809 to that bunch of resistors in the upper
right hand corner of the board (from the front). Connect this to a
suitable jack and mount it on the case. Voila - instant REAL IRQ buss.
(I also use this same IRQ bus for other paks, such as my Hard Disk
HCA, and in the past the PBJ pcpak/rtc). This will make the interrupt
operation MUCH better re: the ACIAPAK devices (I use T2 and T3).

Another thing is that the UART used in the RS-232 pak - a 6551 - has
some design flaws... it'll stop a character  IN MID BIT if the Clear
to send line is disabled. Best bet is to jumper pins 4 to 5 (RTS to
CTS) on the RS-232 pak connector. Also, unless you NEED carrier
sensing, jumper 6,8, and 20 also (DSR/DCD/DTR).. The 6551 also loses
transmit capability if DCD is not present.

If none of the above helps, try a different pak. Also, have you
tried a different terminal package?



-- 
Pete Lyall (OS9 Users Group VP)|  DELPHI: OS9UGVP  |  Eaton Corp.(818)-706-5693
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