Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
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Path: utzoo!linus!decvax!microsoft!mspiggy!danm
From: danm@mspiggy (Dan McCabe)
Newsgroups: net.micro.6809
Subject: Re: Wanted: OS-9 Device Driver Boilerplate
Message-ID: <124@mspiggy>
Date: Thu, 29-Dec-83 18:48:11 EST
Article-I.D.: mspiggy>.124
Posted: Thu Dec 29 18:48:11 1983
Date-Received: Fri, 30-Dec-83 03:59:14 EST
References: <410@bbncca.ARPA> <123@mspiggy>, <418@bbncca.ARPA>
Organization: Microsoft, Bellevue, WA
Lines: 32

For those of you who want to do any sort of expansion of your Coco,
I highly recommend Radio Shack's Color Computer Technical Reference Manual.
It should be available from your local friendly RS dealer.  It contains
theory of operation, schematics, etc. and is well worth the $14 that RS
charges for it.

Regarding the KERMIT and UMODEM protocol support with my /T1 driver:
I cannot say whether it will or will not work with my driver, since I
know nothing about either of those protocols.  Sorry.

Regarding the IRQ line of CoCo:  this line is used for 60 Hz interrupts
which are generated by SAM.  Both IRQ and FIRQ (and NMI) are open-collector
lines.  This means that they can be driven by multiple (open-collector)
drivers to get a wired-or effect (the line will go low when any one
of the drivers goes low).  Unfortunately, access to IRQ is available only
by cutting traces (I have considered making CART go to either IRQ or PIA
depending on external switch setting).

When you have multiple devices generating IRQ, you need to know which
device generated IRQ.  OS/9 significantly helps in this task by scanning
all possible interrupt generators that it knows of.  When one is found,
the appropriate routine is executed.  You must inform OS/9 about such
a device by giving a location, bit mask, and interrupt handler pointer.

From what I have been told, Microware used to provide said boiler plate
routine in their older documantation.  Apparently, they have discontinued
this practice.  If sufficient interest warrants,  I will post a minimal
ACIA driver.

					Happy hacking,
					Dan McCabe
					decvax!microsof!danm