Re: Virtual serial drive

[Michael J. Mahon <mjmahon@aol.com>]

Riccardo <rigreco.grc@gmail.com> wrote:
> Il giorno sabato 8 settembre 2012 21:08:36 UTC+2, BLuRry ha scritto:
>> Yes, the //c can do it.  It is the same 6551 as found in the Super
>> Serial Card.  In fact, I used an Apple //c to develop the Apple Game
>> Server which uses 115.2k baud.  The only problem I've had with it is
>> that my home made serial cable is not properly shielded and is very
>> error prone after a few years of improper storage (whoops!  that's my fault though)
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>> http://hackaday.com/2006/05/25/apple-game-server/
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>> -Brendan
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>> On Saturday, September 8, 2012 1:35:10 PM UTC-5, Riccardo wrote:
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>>> Il giorno sabato 8 settembre 2012 20:19:57 UTC+2, Riccardo ha scritto:
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>>>> Il giorno sabato 8 settembre 2012 12:14:51 UTC+2, Riccardo ha scritto:
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>>>>> Ok, I restart to studied "Inside the Apple IIc" by Gary B. Little
>>>>> 1985, Chapter 11, "The Serial Interface Ports", from page 299 to page
>>>>> 324, it's the great work. And reopen my old book: "Sistemi a
>>>>> microprocessore" by R. Baranzini, D. Capezzuto, G. Dugnani, HOEPLI 1986.
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>>>>> First:
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>>>>> - //c have two 6551 ACIA (Asynchronous Communication Interface Adapter)IC
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>>>>> - PC/MAC typical use Intel 8251A USART (Universal Synchronous Asynchronous             
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>>>>>   Receiver Transmitter)IC, i think.
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>>>>> both IC implement AIA RS-232-C and have two phases:
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>>>>>  Programmer and Communication
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>>>>> Right, my first question:
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>>>>>  At page 307 Figure 11-3 of "Inside the Apple IIc" book, show max
>>>>> set-up speed to 19200 bit/s, but i great currently work up 115200
>>>>> bit/s with ADTPro, Why ?
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>>>>> see you to next step.
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>>>>> Thanks
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>>>>> Riccardo
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>>>> Thanks,
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>>>> Another choice:
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>>>> 1) With Prodos Utilities v 1.0 1984 Apple //c original:
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>>>> 110 - 300 - 1200 - 2400 - 4800 - 9600 - 19200
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>>> 2) with Prodos Utilities v 3.1 speed set-up at:
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>>> 50-75-110-134.5-150-300-600-1200-1800-2400-3600-7200-9600-19200
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>>> 2^4 = 16 combination bits, it's clear that utilities do not use any
>>> combination, by the way:
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>>> at combination 1111 of the 6551 control register, what speed
>>> correspond?  19200 or 115200 bit/s
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>>> Is it possible exists variant of 6551 IC built in //c ? 
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>>> Ric.
> 
> Shielded a serial cable it's no problem, try to twisted single wire is
> more efficient to shield whit metal, like a Ethernet cable. I'll studied
> yours apple game server, it's a great work. By the way if we programmed
> serial port especially in assembler we need to know well the 6551 control
> register, at combination of 1111 what speed correspond ?
> 
> Tanks Bernard.
> 
> Riccardo

Assuming that the 6551s are mapped into /DEVSEL space as it is on an SSC,
all you have to do to run at 115kb is to initialize $C0sB to $10. 

For slot 2, that's $C0AB. For slot 1, it would be $C09B. 

-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon