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Questions tagged [serial]

Serial communication: cables, protocols, ports and controllers like UARTs.

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How to interface with W65C51 UART

I want to build my own computer with retro-ic's. One of those ic's that I want to use is the W65C51 from Western Design Center. I am trying to connect it to a Arduino to learn how to interface with ...
MathijssY Klaver's user avatar
1 vote
5 answers
557 views

Maximum speed of serial I/O bit-banged by 8-bit CPU

I'm interested in the limiting speed of I/O on 8-bit computers. Setting aside the case where parallel cables are used, like the IEEE 488 bus on the Commodore PET; such cables are expensive, which is ...
rwallace's user avatar
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5 votes
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What is an SS97 interface?

I happen to have a Siemens terminal, model S26361-K164-V1, and it seems its interface with the computer is not a more common RS-232, but something called SS97. I couldn't find much about it. It seems ...
rbanffy's user avatar
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5 votes
1 answer
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Getting garbled text when using ADTPro with Apple IIc and serial connection

I am currently having issues while trying to use ADTPro to connect to my Apple IIc and was wondering whether anyone could help me. I am using this serial connection kit and trying to bootstrap from ...
Idrees's user avatar
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5 votes
1 answer
200 views

8251A UART outputs unexpected data

I am currently prototyping an Intel 8088 system (Maximum Mode) on a breadboard. Later I want to move to custom designed PCB. To get some input and output, I wanted to use the 8251A chip. I have two ...
x95's user avatar
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5 votes
1 answer
387 views

Can the MC6850 ACIA signal that it wants to send data but not receive it?

I want use MC6850 ACIA for bidirectional communication, but I am not sure if I've understood it well. I want use an IRQ to interrupt an MCU when the ACIA receives data or has transmitted it. The MCU ...
gilhad's user avatar
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17 votes
7 answers
5k views

Why did Linux standardise on RTS/CTS flow control for serial ports

I've recently been working out how best to wire up a serial cable for a vintage plotter, and it's thrown me down the rabbit hole of RS-232. As far as I can tell, many RS-232 devices which act as DTEs (...
Peter Russell's user avatar
10 votes
2 answers
3k views

Did a serial port card reader sink the prospects of consumer chip card readers?

According to https://groups.google.com/g/alt.folklore.computers/c/z4sm_W1MZXg at the start of the century there were several efforts for secure payments involving chip cards (and chip readers). in ...
rwallace's user avatar
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1 vote
1 answer
307 views

Interfacing with the Commodore 64 IEC Serial Port using Assembly

I'm struggling a bit to find relevant documentation on this subject when it comes to using just assembly. All I've found is either irrelevant or for BASIC. My goal is to be able to send and receive ...
SkyeG06's user avatar
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20 votes
4 answers
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What is the serial protocol commonly used over RS-232 (among other links) and where did it come from?

The RS-232 standard (and ITU V.24 and V.28, which as I understand it are basically the same thing) specifies connectors (DB-25), electrical characteristics (-15 to -5/-3 V for "mark," +3/+5 ...
cjs's user avatar
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7 votes
2 answers
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Which historical Unixes supported terminal I/O with five or six bits per character, and with what character sets?

The specification for termios.h includes a facility for controlling the number of bits per character sent over the serial line, the CSIZE and CSn constants. You can request five, six, seven, or eight ...
zwol's user avatar
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3 votes
3 answers
565 views

Write fault error writing device COM1

I’m trying to send data between a no-name Celeron PC running MS-DOS 6.22 and a Digital VT520 serial terminal. I have connected COM1 to the terminal’s COMM1, but can’t get data to flow in either ...
Jacob Krall's user avatar
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4 votes
1 answer
570 views

How can I connect the Psion 5mx email client to a secure email provider?

My Psion 5mx is connected to the Internet via the built in TCP stack, and serial cable to a raspberry pi running a PPP server. The Psion message suite has an email client which will connect via POP3 ...
Mark Williams's user avatar
10 votes
2 answers
5k views

Is there an obstruction to emulating Gameboy link cable over Wi-Fi?

Emulation these days is well supported for loads of systems, and I understand that original Game Boy and Game Boy Colour are comparatively simple to emulate. Retro gaming is also pretty popular at the ...
Jojo's user avatar
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14 votes
2 answers
3k views

How can I connect a Psion Series 5 PDA to a 64-bit Windows PC?

I have inherited a Psion PDA Series 5, from 1997, along with a serial port RS232 cable, and power supply. It takes industry standard Compact Flash cards, which can be removed and used to transfer ...
Mark Williams's user avatar
6 votes
2 answers
793 views

What voltage does the Psion Series 5 serial port work at?

The Psion 3c and series 5 PDA computers have a 15-pin serial port at the back, which can connect to a PC serial interface via a special cable, or to a battery-powered modem. I have read that the ...
Mark Williams's user avatar
4 votes
1 answer
531 views

How can I make use of a Genius HiSketch 1212 serial-port drawing tablet on a modern PC?

I have a friend that still uses Windows 98 because of a drawing tablet (Genius HiSketch 1212) that he is not able to install in modern systems. He has Windows 98 installed in an old PC that's always ...
Free's user avatar
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8 votes
7 answers
2k views

Why are symmetric bi-directional communication port cables not always crossover cables?

There are a number of bi-directional communication port standards in which cables are used to connect two identical ports, and usually those connect each pin of one port to the same pin of the other ...
user3840170's user avatar
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0 votes
1 answer
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Sony 9-Pin Protocol ("P2", RS-422) Help [closed]

I posted this in video production as well, but it's really more of an obscure serial thing: I have a modern SSD video recorder deck that inexplicably can only be remote controlled by RS-422 (Atomos ...
Adam's user avatar
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4 votes
2 answers
637 views

Send serial data to Macintosh SE?

I am new to anything vintage computing and would like to build a simple project with my Macintosh SE. My Hello World goal here is to simply show a string of text received from the serial port on the ...
Eric Jones's user avatar
23 votes
2 answers
3k views

How does Laplink achieve "high speeds" on standard/legacy serial ports?

I have been using Laplink Pro 4.0a to transfer files between a modern Windows 10 desktop PC (via DOSBox) and several vintage DOS computers. Using a standard null-modem serial cable, in my testing it ...
640KB's user avatar
  • 1,357
11 votes
1 answer
793 views

Is there any public documentation of the LapLink protocol?

Is the protocol used by the DOS Laplink software publicly documented? I seem to remember there were Linux tools that could use it. I cannot find anything useful on their website.
Tomas By's user avatar
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5 votes
4 answers
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9-pin vs 10-pin serial port ribbon cables

I'm (still) putting an old Pentium PC together. I just found that the connectors of my serial port's ribbon cable have one less hole than needed. The socket on the mainboard has 10 pins, but the 10th ...
Tamás Polgár's user avatar
5 votes
1 answer
1k views

Z80 - SIO/0 Frequencies

Z80 board with a SIO/0. I am struggling to understand how CPU and SIO frequencies are related, if they are at all. SIO/0 datasheet didn't help much. If I clock both the CPU and the SIO(TX/RX) from a 1....
Charles's user avatar
  • 411
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1 answer
498 views

What keyboard protocol do IBM 3151 Terminals speak over RJ45

I've recently acquired an IBM 3151 Terminal without a keyboard and I'm not willing to spend any money on an original keyboard. This is why I've tried searching Google for any datasheets of the IBM ...
Unkn0wnCat's user avatar
11 votes
2 answers
370 views

Did any equipment ship with odd serial parity by default?

The asynchronous serial protocol supported an optional parity bit, which could make the total number of "1" bits an even number or an odd number. As discussed in this question, parity could ...
DrSheldon's user avatar
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5 votes
3 answers
1k views

How can I read COM port addresses from BIOS in QuickBasic 4.5?

I have been using the following code to get comm port addresses from BIOS in QuickBasic 4.5: PRINT "Hex addresses for ports 0 to 3 from BIOS." DEF SEG = 0 FOR x = 0 TO 3 z = &H400 + ...
Azathoth's user avatar
  • 125
8 votes
2 answers
760 views

Reverse engineering an RS-422 protocol with access to only one device?

I have a console, but not the main computer it's designed to connect to. My goal is to interface this with a (Linux) PC, and hopefully more than just the keyboard. I have never tried something like ...
noughtnaut's user avatar
10 votes
4 answers
3k views

Is it possible to just construct a simple cable serial↔︎serial and send data from PC to C64?

I recently saw a video made by the famous "The 8 Bit Guy" about PE6502 computer. At 19:41, he successfully sent a text file from his Windows 95 laptop to the PE6502 using only a standard ...
user7710's user avatar
  • 573
10 votes
1 answer
737 views

Where is/was the standard V.35 connector defined?

I'm currently working on a project with an old device that exposes at least one V.35 interface. From my understanding and reading. V.35 commonly used a huge, bulky connector that looked like this: ...
an earwig's user avatar
  • 539
6 votes
1 answer
657 views

How can I send RS-232 serial data to a Tandy plotter reliably?

I recently rescued my Tandy CGP-115 plotter from the attic and had the idea to try and drive it from a modern machine. I have a FTDI CHIPI-X10 RS-232 adapter and installed drivers on a MacBook. I have ...
EBCDIC's user avatar
  • 353
16 votes
2 answers
2k views

How to transfer file(s) between modern Linux host and HP48 handheld calculator?

Context at the time Handheld graphing calculator HP 48 series - Wikipedia, produced between 1990 and 2003, include infrared and serial communication ports to send and receive data and programs between ...
Stéphane Gourichon's user avatar
13 votes
1 answer
896 views

What was the very first device to have an RS-232 serial port

I find the RS-232 standard fascinating as it's one of the standards in computing that's survived - and is still used - for well over 50 years. The only major development has been a change in voltage ...
LawrenceC's user avatar
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8 votes
3 answers
1k views

Is there any virtual hard disk driver over serial port?

NOTE: I'm not looking for a way to transfer files from Linux to DOS over Serial cable Is there any MS-DOS driver to enable a new hard-disk drive (let's say D:), using a disk image on another computer ...
R. F. Luis's user avatar
8 votes
1 answer
1k views

Will any serial mouse connect to Classic Macs?

The Macintosh 128k, 512k, and Plus use a DE-09 Serial port for the mouse. Is there some proprietary data-transfer method? Or is any DE-09 Serial mouse compatible? Furthermore: has anyone documented ...
Michael's user avatar
  • 183
3 votes
3 answers
461 views

Creative uses for serial port? [closed]

I know it's still used for many industrial microcontrollers but that's not what I am asking; I also know that it's quite slow. It's just that I hate seeing an unused port on my desktop pc, while all ...
MrJohn's user avatar
  • 49
14 votes
2 answers
1k views

Can I trigger the Amiga ROM debugger from the boot prompt?

Suppose I have an Amiga computer without any working boot disks. Is it possible to trigger the built-in ROM monitor (RomWack or SAD, see https://theamigamuseum.com/amiga-kickstart-workbench-os/guru-...
user3570736's user avatar
  • 1,802
13 votes
1 answer
4k views

Connecting Panasonic "Penwriter" RK-P400C to modern PC using USB to serial cable

I have a Panasonic "Penwriter" model RK-P400C electronic typewriter/plotter from circa 1985 I'd like to be able to connect to a modern PC. And hopefully even use to draw graphics! Bought in almost new ...
MattyZ's user avatar
  • 351
3 votes
2 answers
690 views

Basic test for a RS232 serial terminal

I have a serial terminal that is not working. It's a VT525 using an external monitor (of course) and PS/2 PC keyboard. The self-test passes fine; setup works fine. I can echo characters when local ...
user avatar
4 votes
3 answers
2k views

What trial-and-error method to use for determining serial terminal settings (RAC2-8-EK)

I have an old device that I am sure works on either 1200,2400,4800 or 9600 bauds (actual setting is controlled by physical switches that I don't have access to) What's the most efficient method (...
user3280964's user avatar
6 votes
4 answers
1k views

Connect IBM 3481 terminal to RS232?

I recently acquired an IBM 3481 terminal. It has a parallel port, a DB-15 port (I believe for a twinax-T connector), an 8P8C keyboard connector, and a PS/2 connector. Since I don't have a vintage IBM ...
65a's user avatar
  • 63
8 votes
1 answer
546 views

Reading data over serial from an old punched tape reader

I have an old GNT-4601 punched tape reader/punch that I'm trying to connect to a modern computer. Using the DTE port and a usb-to-serial adapter, I'm able to send data to the punch but I can't read ...
Matt Bierner's user avatar
14 votes
7 answers
6k views

Transfer files to DOS over serial cable from Linux?

I have a modern Linux computer and a 286 computer running DOS. I would like to transfer files from the Linux computer to the DOS computer over a null modem serial cable. I know you can use INTERLINK....
Sydius's user avatar
  • 2,654
38 votes
8 answers
14k views

Why do articles use the term "UART" instead of "serial port"?

I am learning about old computers, and I have found the following image from this article: They use the terms "UART" instead of "serial port" and "UART driver" instead of "serial port driver", I have ...
user7127's user avatar
  • 381
1 vote
1 answer
239 views

Is this a UART chip? [closed]

Based on my understanding, a UART chip is a chip that exists on a serial card, and it is responsible for the actual sending and receiving of data over the serial port. I want to see what a UART chip ...
user8240761's user avatar
8 votes
3 answers
1k views

Serial Receipt Printer Garbage

I connected a vintage serial matrix receipt printer (Datamega DPN-233) via FTDI to my MacBook's USB. It performs its own self-test without problems, prints an example and the RS 232 configuration (...
user1936279's user avatar
6 votes
3 answers
4k views

9-pin port for both RS-232 and Atari joystick?

A 9-pin RS-232 serial port looks superficially quite similar to the Atari joystick port. I don't suppose you could just plug a joystick into a serial port and have it work, but suppose you took this ...
rwallace's user avatar
  • 63.1k
13 votes
6 answers
1k views

How was parity used with modems?

On the back of this question which talks about 5- and 6-bit communications, I remember back in the BBS days that it was common to set your terminal to 8N1, (a.k.a. 8 bits, no parity, 1 stop bit) to ...
bjb's user avatar
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27 votes
9 answers
3k views

What were the applications of 5/6-bit serial port formats?

Traditional PC serial ports, based on members of the 8250/16550 UART families (or their clones within SuperIO chips) support some unusual serial data formats, specifically 5- and 6-bit data, and 1.5 ...
user avatar
15 votes
2 answers
547 views

Connecting an Apple //e with a Super Serial Card to an Android device via a USB to DB25 cable

I have an Apple //e, and I quite enjoy using it as a dumb terminal to my Raspberry Pi from time to time. Recently, I came across a few cords that could connect my Android phone (a Pixel) to the DB25 ...
Zachary Swanson's user avatar