[Coco] Questions about the Coco3 GIME Timer

[Joel Ewy]

Stephen H. Fischer wrote:

> Hi,

>

> I do not know if the 6522 can still be obtained but if they are available

> you might save a lot of work.

>

>   

Define "available".  ;)  Not that I would ever recommend violating any
of these classic computers, but if they're already dead, they might be
organ donors:  If you have the motherboard out of an old Mac 128, Mac
512, or Mac Plus that you've turned into fish tanks, you could liberate
a 6522.  You might also find one in a Commodore Vic-20, or certain
external Commodore floppy drive units.  Maybe also some other early CBM
computers.  Also the Amiga has an 8520, which is just about the same
thing, I think.

JCE

> http://www.zimmers.net/anonftp/pub/cbm/documents/chipdata/6522-VIA.txt

>

> o Two 8-bit bidirectional I/O ports

> o Two 16-bit programmable timer/counters

> o Serial data port

> o TTL compatible

> o CMOS compatible peripheral control lines

> o Expanded "handshake" capability allows positive control

>   data transfers between processor and peripheral devices

> o Latched output and input registers

> o 1 MHz and 2 Mhz operation

> o Single +5V power supply

>

> PORT B (PB0-PB7)

>

> Peripheral   Port   B   consists  of  eight  bi-directional  lines  which

> are controlled  by  an  output  register and a data direction register in

> much the same  manner  as  the  Port  A.  In  addition,  the polarity of the

> PB7 output signal  can  be  controlled  by  one  of  the interval timers

> while the second timer  can  be  programmed  to  count  pulses  on  the  PB6

> pin. Port B lines represent  one  standard  TTL  load  in  the  input  mode

> and  will drive one standard  TTL  load  in  the  output  mode.  In

> addition, they are capable of sourcing  1.0  mA  at  1.5  Vdc  in  the

> output  mode to allow the outputs to directly  drive  Darlington  transistor

> circuits.

>

> Stephen H. Fischer

>

>

> ----- Original Message ----- 

> From: <jdaggett at gate.net>

> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>

> Sent: Wednesday, February 14, 2007 1:20 PM

> Subject: Re: [Coco] Questions about the Coco3 GIME Timer

>   

>> No problem. Kind of doing the same here. I am in the process of designing

>> a

>> CPLD to do PWM to drive servo motors to automate a telescope. I want to

>> consolated a few PC Basic programs and modifiy to run on a  COCO1/2/3. I

>> will

>> have to off load some tasks to dedicated hardware.

>>

>> james

>>     

>

>

>