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Apple IIe DIY Serial Card?

thenzero

Experienced Member
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Feb 19, 2021
Messages
424
Location
Perry, GA
I'm curious what ya'll think about this idea.

The Super Serial cards are really expensive on eBay currently so I'm looking around and thinking about alternatives.

Here is what I've been mulling the last few days. Looking for general opinions as well as specific technical references to help out with any of them.

Idea #1: Prototype card + 6551 chip

Basic idea is to buy a prototype card ($10) and put a 6551 chip ($7) on it, follow some existing designs out there
Pros: Very clean implementation, probably would "just work" with existing term software
Cons: ???

Idea #2: TTL to RS232 over Gameport

Basic idea is to implement the circuit discussed in the Apple II Redbook, starting on p114 ("A Simple Serial Interface"). This uses the I/O pins on J-14 to get TTL level output and then I would use an external TTL to RS232 converter.
Pros: Nothing to buy, easy to pin into the 16 pin gameport connector
Cons: Probably would NOT "just work" with existing SW

Thoughts?
 

VERAULT

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Will it be SSC compatible? Because I would need it to run ADTPro which is what I mostly use the SSC for in the first place.

And YES I have been waiting and asking for something like this for he past couple years... but all the apple II folks keep saying "the SSC is still affordable at $75.00"

Its not affordable at that price....

Your second idea is interesting, but without support in existing software I dont see the usefullness
 

thenzero

Experienced Member
Joined
Feb 19, 2021
Messages
424
Location
Perry, GA
That's the idea. Then you could plug it in to (for example) an ESP8266 and do serial over WiFi or whatever.

One problem that I already noticed with my plan is that looking at the SSC schematic, I would need the 6551A (2MHz) not the 6551 (1MHz). Also it looks like you need some other kind of chip to sit between the IIe bus and the 6551A chip. I did see this old thread where the guy did something very similar (except he skipped the RS232 and went straight to an ESP8266 at TTL I guess?). He's got a 6551A, hex inverter, and some other chip I can't make out.
 

thenzero

Experienced Member
Joined
Feb 19, 2021
Messages
424
Location
Perry, GA
Good call, thanks. That link has a lot of great info plus some leads.

Also, looking deeper at the 6551 datasheet, maybe I'm wrong about needing the -A. The datasheet seems to indicate the 6551 can do either mode. I guess I'll just get a handful of them and try it out.
 

thenzero

Experienced Member
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Feb 19, 2021
Messages
424
Location
Perry, GA
Ohhh, I figured out what that other chip is on Dan Werner's board. It's a M27C64A-15F1 EPROM.
 

VERAULT

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Messages
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Connecticut, USA
Well it will need its own ROM. So makes sense.
So once you getting a working prototype are you going to maker some gerbers in eagle? Is that the plan?
 

VERAULT

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Messages
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Hmm April of last year ehh? I guess all we need now is an online BOM on one of the electronic resellers and were ready to go.

Funny how these things DONT EVEN SHOW UP ON THE FORUMS!!!! jesus....
 

thenzero

Experienced Member
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Feb 19, 2021
Messages
424
Location
Perry, GA
Yeah I think this guy did the hard work already AND he focused on modern availability and ssc compatibility.
 

thenzero

Experienced Member
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Feb 19, 2021
Messages
424
Location
Perry, GA
Well, I priced out the components listed on that page. Bottom line is it doesn't come out much cheaper then the eBay prices unless you happen to have all these components laying around already.
 

thenzero

Experienced Member
Joined
Feb 19, 2021
Messages
424
Location
Perry, GA
The EEPROM is probably the most expensive single component.

Here's a cart I built at Jameco. Take this with a grain of salt...I'm pretty sure these are the right components but I'd want to run it by someone with more expertise before I ordered them.

Jameco Shopping Cart
www.Jameco.com
1-800-831-4242
Export Date,01/17/2022

Part Number, Description, Quantity, Unit Cost, Total
74843,"IC,EEPROM,28C256-15,5V 32kx8,D","5","$12.25","$61.25"
45031,"IC,74HCT245N,DIP-20,TRI-STATE","5","$0.89","$4.45"
27879,"CRY,OSC,1.8432MHz,100ppm, 5V@4","5","$2.49","$12.45"
39159,"IC, PALCE22V10D-15PC,DIP-24, P","5","$3.95","$19.75"
2308327,"IC,MAX3232CPE+, TRUE RS-232 TR","10","$3.25","$32.50"
, , ,Subtotal,"$130.40"

Add another $60 for the W65C51N from eBay ($12x5) or wherever you can get them, if you can get them.

Total for components for 5 boards comes to about $190. Then you have to add in the cost of manufacturing the PCBs. Cost for that is a big unknown to me, let's guess $50-100. Maybe $10 for other supplies (capacitors, etc).

If you assembled them yourself, you're up to about $50-60/card. To me, that would not be worth all the effort to get one card.

Thoughts?
 

thenzero

Experienced Member
Joined
Feb 19, 2021
Messages
424
Location
Perry, GA
Two more thoughts on this.

1- if someone wanted multiple cards, doing this might make more sense since then the effort to build them saves you maybe $30-40 per card. That doesn't make sense for one, but definitely adds up for multiples.
2- I still want to get in touch with that Dan Werner guy. His design appeared much simpler in that photo he posted- all it showed was an EPROM, hex inverter, and 6551 chip. If that design actually works as it appears, it would be far cheaper and easier to implement...I think.
 
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