A new Serial Card

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A new Serial Card

Hello Smile New here Biggrin

I've posted a little about this in the facebook group, but I thought I'd join up here and start a thread which would leave a trail and place for constructive comment and discussion.

Super Serial Cards aren't actually that common in the UK/Europe, whilst they are about 10-a-penny over in the US. Shipping them over here is the killer. With that in mind, as a new Apple IIe owner without an SSC I started looking at the possibility of rebuilding the thing at a price that would be less than what you'd pay to have them shipped over.

I've got as far as laying out the schematic and most of the PCB in KiCAD, but some discussion on facebook got me thinking further.

Firstly, the 6551 isn't that available anymore, and WDC's final run of them is irrevocably broken. Secondly, something that worked reliably at modern speeds would potentially be attractive to people.

With that in mind, I've started to look at using an ARM microcontroller to emulate a SSC/6551, whilst also giving access to its own UARTs for very high speed communications. In addition it would seem to be very easy to pop on a GPIO header for a Raspberry Pi and get Apple2Pi plugged in too.

As a first step I've got some small breakout cards for the Apple II Bus on order, the design of which, along with gerbers is here: https://goo.gl/tSZMsV - it's completely open source, please feel free to share, make your own, derive, munge and do whatever with it. I will be doing exactly the same with the design/code for the full serial card.

Clearly something like this has a huge amount of capacity to do a huge amount more, so I'd be very interested in thoughts/ideas/input/whatever, basically! Smile

d.

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Re: A new Serial Card

I don't know why no one replied to this, but it sounds fantastic. I support any Apple II homebrew, I think it's an important step in preserving the legacy.

I would be interested to see how you go keeping the costs down, as I still believe it would be cheaper to import SSCs than it would be to produce new cards. A breadboard prototype is one thing, but the costs involved with producing PCBs and everything else tends to build up. Would you have a minimum number to sell to break even? This might not be a concern - if not, so much the better, as you're doing a service to the Apple II community!

For what it's worth, I had to wait a while to get my two SSCs at the right price (I'm in Australia), but I eventually did get them. You may also want to consider buying a complete Apple II system which includes an SSC, as the total price of the unit plus peripherals will often be cheaper than buying each component individually. You normally at least get some new spare parts, or at most, another Apple II to play with! Smile

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Re: A new Serial Card

CWJ_Wilko wrote:
I don't know why no one replied to this, but it sounds fantastic.

Yeah, replies here are a bit scarce at times.
Personally, I did not respond because of the direction of the project. I don't know a lot about the ARM side,
so I thought my comments would be somewhat irrelevant. But that doesn't mean we're not interested.
I recently made a version of a Serial Card, but I added an Ethernet interface to it. (see SERIAL ETHERNET CARD here)
This was a long-time personal ambition, though there is no real magic to it. It's still a serial stream presented
to the Apple ][ bus and requires all the delays associated with the legacy Serial card. (which somewhat limits
performance) But I think it was worth it and I know there's nothing else like it out there. (Serial Ethernet combo)

I always encourage new developments for the Apple ][, as others do as well but sometimes (for me anyway) there's
not enough I can add constructively, so I remain silent & see where it goes. Seems safer I guess. :mac:

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Re: A new Serial Card

Hullo - Smile

If the boards are small enough (<=100mm x 100mm), they can be produced for approximately $2/each. I'm fairly confident they can be kept to the sort of size that would allow that.

I think we'd be looking at approximately £30/card in the UK. My aim would be to produce a small number, along with the design, and then people can make their own as the design would be completely open. Experience suggests this has worked pretty well with various peripherals that have been designed for the BBC Micro.

I'm happy to spend money on development/design, and time I spend on hobbies is time enjoyed so that's free. Hence anything I end up producing will basically just ensure that it covers the costs of the parts needed to build it, but I won't personally be going into full scale production! Smile

Hopefully the edge connector breakouts will be here next week and I can start getting going on this. Thinking's evolved a bit further and instead of using a ROM on the card, it seems quite feasible to use sram, having the microcontroller download the ROM code into the RAM when the machine's switched on. This would enable people to completely reconfigure the card at will, just by reprogramming the uC (and CPLD which will be necessary to hold the 6551 registers). I've not completely made up my mind on the uC yet, I may yet plump for an AVR as it's a bit easier to deal with (although not as powerful).

I'll have a peek at the ethernet, that looks interesting!

d.

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Re: A new Serial Card

>double post<

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Re: A new Serial Card

macnoyd wrote:
SERIAL ETHERNET CARD here[/b])

Ooh - I note you didn't bother replicating the Terminal/Modem jumper. To all intents and purposes, is there no point in replicating that functionality?

d.

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Re: A new Serial Card

I didn't think it was worth replicating the Terminal/Modem jumper because this card would be used primarily in terminal mode.
So I wired it that way. You can simply change the DB9 or DB25 end (whatever you use) to change from one mode to the other,
so it really becomes a moot point of having it on the board. Also, I needed the real-estate for the Ethernet card anyway. Smile

Since the Super Serial Card, what other serial card flips modes like that? I think this was a handy feature back in the day but
was short-lived given the ease of changing cables. (or inserting those life-saving modem-eliminator adapters) Smile

For transferring files, communicating with other computers, or anything NOT going to a modem device, Terminal mode is the default
way to go IMHO.

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Re: A new Serial Card

I really like to see upcoming enhancements for our Apple II machines... but...

what I'm really missing is to keep RS232 and Printer capabilities onto one board.

Why... because uthernet II is always in place but to add RS232 and printer capabilities to your Apple you always have to add 2 cards as of today (to my knowledge).

In the PC world cards combining such capabilities where common in the past... so why not designing a combo card without Ethernet? or if feasible with Ethernet... but again uthernet is commonly wide spreaded and supported.

My five cents...

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Re: A new Serial Card

So add parallel on to the card too? Are many people printing from Apple IIs?

As it stands, I'm going to not over-stretch myself at this stage - this is my first foray into the Apple world, so I'm fulfilling a need that I have for myself whilst trying to help the serial situation go "a bit faster" Biggrin

That said, as the design will be completely open, there's nothing to stop someone else adding further functionality!

d.

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Re: A new Serial Card

Parallel cards (to me) were the lowest of low-level comms cards that had limited cable length, had a bulky wire and
huge Centronics connector on the end. I couldn't wait to go serial after my old Centronics printer died.
Just my opinion FWIW, but I'd let Parallel connections go the way of Morse Code. Blum 3

I built Ethernet into the design of the Super Serial Card because there's so much out there that supports the SSC and
with an Ethernet interface running parallel to the Serial comms, you get the best of both worlds. Omitting the jumper
doesn't mean the card can't do Modem or Terminal comms, because all that jumper does is swap wires at the serial cable
end. It was more of a convenience than anything else. Fortunately, Ethernet doesn't make those distinctions.

Traditionally, Slot 1 was always designated to be the printer slot and Slot 2 designated as the modem slot. That
hasn't changed from the past setups and you still need 2 cards IMO, so having a printer card that can communicate
Serially or by Ethernet can only add to your available options.

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Re: A new Serial Card

Just to stir things up again, my biggest gripe with the Uthernet II (and many, many other cards that have been produced) is that they become scarce after a few years. I missed out buying an Uthernet II a couple of years ago and have been on the waiting list ever since. I would support any alternative that brings ethernet to my Apple II. It's not anyone's fault, these cards aren't being mass produced, but it's a massive pain in the ass when you're literally waiting years (or paying extortionists on eBay) for a 'popular' 'widely used' card.

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Re: A new Serial Card

This is a perennial issue, which is why I'm keen to make sure that any designs are open - that means anyone who's feeling enterprising can do a run of 10 or 20 and keep supply going. If people don't like what one person's charging they're free to look into doing it cheaper themselves etc.

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Re: A new Serial Card

Since a slot or port can have up to 16 i/o registers and a 6551 takes up only 4 why not add another 6551 and use one for modem and the other for printer? There's room there for 4 6551s hardware-wise; layout is another matter.

Cheers!
Andy

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Re: A new Serial Card

If it's a CPLD + Microcontroller, the world is essentially your oyster. The other address space can be used to set any other mode or behaviour you'd like to implement!

(e.g. printer/terminal mode, higher speeds, buffering options)

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