I acquired an Apple IIe enhanced and it came with an MPC AP-SIO card installed. It has a DB-25 connector on the other end of the ribbon cable. It looks like a clone serial card. I can find reference in on-line copies of Byte magazine and google books to the IBM-SIO card and to other MPC cards but not this one. Anyone familiar with these? Anyone know the dip settings?
Thanks.
Hi,
I can't help with the MPC SIO card. But I have a very similar question.
I'm also interested in finding out more about my SIO card. This is a card from an Apple IIe and connects the printer (ImageWriter) via a DB25 connector. Two labels on the card say "NPARA-2" (and "N-PARA 2"), but I've been unable to find any documentation on this particular card, nor anything relating to its name. All markings on its ICs were wiped out. I guess it's also some clone/unofficial vendor...
20191107_195916-1.jpg
I'd also be grateful for any hints...
Thanks...
Sorry. I don't recognize that either. Anything on the back?
It looks like a clone of the Apple Communications Card. It uses a 6850 style serial chip instead of the 6551 like used in the Super Serial Card. It is suitable for printers, but will be a poor performer with modems faster than 300bps. Even at 1200bps it will swamp the machine with interrupts because there isn't even a one byte send or receive buffer like the 6551 has.
[quote=softwarejanitor]It looks like a clone of the Apple Communications Card. [/quote]
Thanks. I looked up the Hitachi IC datasheet and figured it was something like that. I guess I'll hold on to it but will keep my eyes out for another serial card.
[quote=softwarejanitor]
It looks like a clone of the Apple Communications Card.
[/quote]
There are several cards with a 6850.
[quote=softwarejanitor]
Even at 1200bps it will swamp the machine with interrupts because there isn't even a one byte send or receive buffer like the 6551 has.
[/quote]
The registers of the 6850 and 6551 are nearly the same. There is one data buffer and the shift register. The difference between these chips is the internal baud rate generator in the 6551 upto 19200Baud and the tricky usage of 115kBaud. The 6850 can run upto 1Mb/sec but has no baud rate generator. There are only some dividers for the external clock. 57600 Baud, 115 and 230kBaud are ok. Over 30years ago my 6850 card ran at 57600Baud, and in the future I will use this chip with 921kBaud. Yes, in an Apple IIe :-) But no interrupt and no handshake at this speed.
Regards
Ralf
In practice the 6850 really struggles to do any kind of high speeds, the 6551 isn't much better, but even a one byte send and receive buffer is a huge improvement in terms of limiting loss of characters. It is a pity that there really weren't cards made for the Apple II that used a UART with a multibyte FIFO like the 16550B or newer chips. I actually was contemplating designing one using a modern chip but the consensus on the forums was that nobody would be interested in anything that wasn't 110% Super Serial Card compatible because they'd want to be able to run vintage software unmodified. So that idea got put on semi-permanent hiatus. I actually found a couple of really good options for chips to use but unless I end up with a personal need I probably won't try to build one.
Other cards I've used over the years that use the 6850 chip include the CCS 7710 and the CPS Multifunction Card. They both show a measurable drop in throughput even on file transfers at speeds above 2400 compared to a Super Serial Card. For displaying text like a terminal program it is even worse, you can see the handshaking happen, especially when the screen scrolls, and especially in 80 column mode on a //e, because that operation requires quite a few CPU cycles to flog the bytes around in screen memory on both the regular and AUX RAM.
[quote=softwarejanitor]UART with a multibyte FIFO like the 16550B or newer chips.[/quote]
The availability of a proper UART was one of the reasons I stopped using the Apple I had in favor of a newer (am386dx) PC.
[quote=softwarejanitor]I actually was contemplating designing one using a modern chip but the consensus on the forums was that nobody would be interested in anything that wasn't 110% Super Serial Card compatible because they'd want to be able to run vintage software unmodified. So that idea got put on semi-permanent hiatus. I actually found a couple of really good options for chips to use but unless I end up with a personal need I probably won't try to build one.[/quote]
Interesting. I wonder what the cost would be do build a few of them.
[quote=softwarejanitor]
Other cards I've used over the years that use the 6850 chip include the CCS 7710 and the CPS Multifunction Card. They both show a measurable drop in throughput even on file transfers at speeds above 2400 compared to a Super Serial Card. [/quote]
Probably an issue of the firmware. Neither the Apple II nor the firmware of the cards are realy qualified for interrupt service. This is the disadvantage of the whole Apple II family, IMHO. If you use your own operating system it's possible to get higher serial speed and better interrupt latency.
[quote=softwarejanitor]
For displaying text like a terminal program it is even worse, you can see the handshaking happen, especially when the screen scrolls, and especially in 80 column mode on a //e, because that operation requires quite a few CPU cycles to flog the bytes around in screen memory on both the regular and AUX RAM.
[/quote]
The quality of the Apple IIe 80column firmware is awful. Running my own BIOS with the p-System I wrote a complete new firmware, and this was faster. Of course :-) Another bottleneck is the hardware of the IIe 80column implementation. A 6845 based (Videx) card is faster, especially when the screen scrolls. If the IIe firmware wants to scroll up one line the code must read 1840bytes and must write 1920bytes in the screen buffer. If a 6845 based card scrolls up one line it must read and write just 2bytes but not in the screen buffer, just in the controller chip.
Regards
Ralf
[quote=RalfK]
If a 6845 based card scrolls up one line it must read and write just 2bytes but not in the screen buffer, just in the controller chip.
[/quote]
Argl, no edit function :-(
The videx firmware must write also 80bytes to the screen buffer.
Regards
Ralf
[quote=SavingOldKit]
[The availability of a proper UART [...]
[/quote]
I think there was a serial card with a SCC 8530 which is also used in the Macintosh family, beside an embedded 6502 on LocalTalk adapters for printers including Imagewriters and IBM-DOS PCs. I found a picture of a "DIGICARD D-NET" with a 8530 and two serial connectors but I've never seen real hardware.
http://www.ralf-kiefer.de/A2/digicard_serial_front.jpg
There were also cards with a 8250 (hm...?) or the Mostek MK3801 which is the Z80 compagnion.
[quote=SavingOldKit]
I wonder what the cost would be do build a few of them.
[/quote]
Find a serial controller chip which is available on the market, which fits to the AppleBus (5V not 3.3V), and someone who constructs this card! :-)
Regards
Ralf
[quote=SavingOldKit]
[quote=softwarejanitor]UART with a multibyte FIFO like the 16550B or newer chips.[/quote]
The availability of a proper UART was one of the reasons I stopped using the Apple I had in favor of a newer (am386dx) PC.
[quote=softwarejanitor]I actually was contemplating designing one using a modern chip but the consensus on the forums was that nobody would be interested in anything that wasn't 110% Super Serial Card compatible because they'd want to be able to run vintage software unmodified. So that idea got put on semi-permanent hiatus. I actually found a couple of really good options for chips to use but unless I end up with a personal need I probably won't try to build one.[/quote]
Interesting. I wonder what the cost would be do build a few of them.
[/quote]
If I remember right the BOM cost would be about $40-$50 and the cards would have sold in the $75-$100 range. Some of the chips I was looking at did 2 or even 4 ports and some of them had as many as 64 bytes of FIFO. But there was less than zero interest in them. By that I mean there were a bunch of nay-sayers who said it was either pointless because part of the charm of the Apple II is that it is slow or underpowered, that they wouldn't buy anything that wasn't 110% Super Serial Card compatible because nobody was capable of writing any new software or patching old software, that anything more than the $25-$30 that Super Serial Cards sell for used is just way too expensive and they can't spend that kind of money on an Apple II, etc.
I had a bunch of stuff I was working on but I pretty much gave up on all of it because of the negativity. I'm still building a few things for myself but I'm not planning on making any attempt to try to build anything in quantity.
If you are interested in some of my research work for various cards let me know. I'm happy to share if someone else is interested in building some for themselves or completing some of the designs that are 1/2 finished.
[quote=softwarejanitor]
nobody was capable of writing any new software or patching old software
[/quote]
That's obviously crap. Those people are out there. Hell, I was writing assembly to drive the Disk II and other devices and *cough* patching software on the IIe, Atari, and TRS-80 as a thirteen year old. Sure, I have less time thirty-five years later but I also have more experience and funds for my hobbies.
[quote=softwarejanitor]
If you are interested in some of my research work for various cards let me know. I'm happy to share if someone else is interested in building some for themselves or completing some of the designs that are 1/2 finished.
[/quote]
Thanks I'll PM you.
[quote=softwarejanitor]
[quote=SavingOldKit]
[quote=softwarejanitor]UART with a multibyte FIFO like the 16550B or newer chips.[/quote]
The availability of a proper UART was one of the reasons I stopped using the Apple I had in favor of a newer (am386dx) PC.
[quote=softwarejanitor]I actually was contemplating designing one using a modern chip but the consensus on the forums was that nobody would be interested in anything that wasn't 110% Super Serial Card compatible because they'd want to be able to run vintage software unmodified. So that idea got put on semi-permanent hiatus. I actually found a couple of really good options for chips to use but unless I end up with a personal need I probably won't try to build one.[/quote]
Interesting. I wonder what the cost would be do build a few of them.
[/quote]
If I remember right the BOM cost would be about $40-$50 and the cards would have sold in the $75-$100 range. Some of the chips I was looking at did 2 or even 4 ports and some of them had as many as 64 bytes of FIFO. But there was less than zero interest in them. By that I mean there were a bunch of nay-sayers who said it was either pointless because part of the charm of the Apple II is that it is slow or underpowered, that they wouldn't buy anything that wasn't 110% Super Serial Card compatible because nobody was capable of writing any new software or patching old software, that anything more than the $25-$30 that Super Serial Cards sell for used is just way too expensive and they can't spend that kind of money on an Apple II, etc.
I had a bunch of stuff I was working on but I pretty much gave up on all of it because of the negativity. I'm still building a few things for myself but I'm not planning on making any attempt to try to build anything in quantity.
If you are interested in some of my research work for various cards let me know. I'm happy to share if someone else is interested in building some for themselves or completing some of the designs that are 1/2 finished.
[/quote]
Once I finish my RAM cards, I plan to work on my "Mouserial" card which has some of the capabilities you are referring to, in particular the multibyte FIFO. In the Mouserial, serial TX data is sent to a 7 MHZ AVR microcontroller, which can buffer it as necessary. The only issue is that Mouserial's serial functionality was designed specifically to talk to a PC and do ADTPro, so the serial interface is through a USB port. I didn't think there was much interest in a new, non-SSC-compatible serial card, as you said, but once I finish the Mouserial, it would be easy to do a new hardware version with a serial port instead of USB.