| User Port Pins [message #374040] |
Tue, 25 September 2018 13:42  |
cbmeeks
Messages: 23
Registered: February 2005
Karma: 0
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I'm curious about how to access certain pins of the C64 User Port. Going by the pinout here:
https://www.c64-wiki.com/wiki/User_Port
I see there are some pins I'm not familiar with.
4 CNT1 Counter 1, from CIA #1
5 SP1 Serial Port 1, from CIA #1
6 CNT2 Counter 2, from CIA #2
7 SP2 Serial port 2, from CIA #2
8 /PC2 Handshaking line, from CIA #2
9 ATN Serial attention in
....
B /FLAG2 Flag 2
....
M PA2 PA2
I have a basic idea what the counters are for but I'm looking for more detailed information on all of those pins.
Are there any programming and/or schematics out there that indicate how to use them in various projects?
Thanks
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| Re: User Port Pins [message #374107 is a reply to message #374040] |
Thu, 27 September 2018 11:56  |
Pekka Takala
Messages: 73
Registered: March 2012
Karma: 0
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Member |
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On 25.09.2018 20:42, cbmeeks wrote:
> I'm curious about how to access certain pins of the C64 User Port. Going by the pinout here:
>
> https://www.c64-wiki.com/wiki/User_Port
>
> I see there are some pins I'm not familiar with.
>
>
> 4 CNT1 Counter 1, from CIA #1
> 5 SP1 Serial Port 1, from CIA #1
> 6 CNT2 Counter 2, from CIA #2
> 7 SP2 Serial port 2, from CIA #2
These come from appropriate pins from appropriate CIA chips. You can use
these for fast serial connections. The clock comes from cnt pin and data
from sp1. Or if you input something, the chip reads from sp1 when clock
signal comes.
> 8 /PC2 Handshaking line, from CIA #2
I do not exactly know about this.
> 9 ATN Serial attention in
I do not know why this is here. It is the same signal as in serial port.
Could it be that CBM thought that serial ports could be used with fast
drives?
> ...
> B /FLAG2 Flag 2
A handshake line. This can be tied to a interrupt.
> ...
> M PA2 PA2
You can use this pin as PB0-7. It has a DDR register and you can use it
as input or output. Usually used as handshake line.
>
>
> I have a basic idea what the counters are for but I'm looking for more detailed information on all of those pins.
>
> Are there any programming and/or schematics out there that indicate how to use them in various projects?
>
> Thanks
>
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| Re: User Port Pins [message #374138 is a reply to message #374132] |
Fri, 28 September 2018 14:14 |
Pekka Takala
Messages: 73
Registered: March 2012
Karma: 0
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Member |
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On 28.09.2018 06:40, Janne Johansson wrote:
> On 2018-09-27 17:56, Pekka Takala : cbmeeks wrote:
>>
>>> 9Â Â Â ATNÂ Â Â Serial attention in
>>
>> I do not know why this is here. It is the same signal as in serial port.
>> Could it be that CBM thought that serial ports could be used with fast
>> drives?
>>
>
>
> Could "Serial Attention" be the same as Ring Indication where a modem
> tells the computer to prepare for an incoming call?
>
I do not think so, because it will interfere with disk drives. Incoming
call attention is given by rs232 lines anyway.
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| Re: User Port Pins [message #374139 is a reply to message #374040] |
Thu, 27 September 2018 20:53 |
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Originally posted by: nospam.Ed.Vance
09-25-18 10:42 cbmeeks wrote to All about User Port Pins
Howdy! cbmeeks,
I couldn't find my C=64 Programmers Reference Manual to help You but
go to www.zimmers.net if You have a internet connection.
He has all kinds of information on Commodore Products.
cb> @MSGID: <5BAABE2F.2792.cbm@capitolcityonline.net>
cb> I'm curious about how to access certain pins of the C64 User Port.
cb> Going by the pinout here:
cb> https://www.c64-wiki.com/wiki/User_Port
cb> I see there are some pins I'm not familiar with.
cb> 4 CNT1.Counter 1, from CIA #1
cb> 5.SP1.Serial Port 1, from CIA #1
cb> 6.CNT2.Counter 2, from CIA #2
cb> 7.SP2.Serial port 2, from CIA #2
cb> 8./PC2.Handshaking line, from CIA #2
cb> 9.ATN.Serial attention in
cb> ...
cb> B./FLAG2.Flag 2
cb> ...
cb> M.PA2.PA2
cb> I have a basic idea what the counters are for but I'm looking for more
cb> detailed information on all of those pins.
cb> Are there any programming and/or schematics out there that indicate how
cb> to use them in various projects?
cb> Thanks
.... "It Shouldn't Be This Hard" - Leo Notenboom
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