6 ms·

Arn't there a serial (COM) port available on that laptop ? It was kind of ubiquitous at those days. This website [1] says there were two of them. Solving the pr

by ruslan 2y ago

Arn't there a serial (COM) port available on that laptop ? It was kind of ubiquitous at those days. This website [1] says there were two of them. Solving the probem with Zmodem would be trivial. The software (terminal) is already there, it seems. 1. https://everymac.com/systems/apple/powerbook_duo/specs/mac_powerbook_duo280c.html#macspecs2 https://everymac.com/systems/apple/powerbook_duo/specs/mac_p...

gcp123 2y ago
Yes, it had those ports. Just like Kevin McCallister could've called the police in Home Alone, I think the author preferred this to become an extraordinary story more than the simplest possible solve.
perakojotgenije 2y ago
That's the first thing that came to my mind. I remember connecting two laptops using LPT or COM cable and transferring files using norton commander (if I remember correctly) 30 years ago.
rvense 2y ago
Apple used 8-pin mini DIN connectors for serial. The author might not have had the right cable.
- hi-v-rocknroll 2y ago
  A Farallon EtherWave provides Ethernet directly.
- ruslan 2y ago
  There are plenty of mini-DIN connectors and serial cables for mac on ebay. You need just three wires for serial line to work. I would strip the wires and plug them in without any connector. :)
- inferiorhuman 2y ago
  Classic macs had RS-422 not RS-232 ports so you'll need more than just a dumb cable to get it working with a PC.
  - kalleboo 2y ago
    The Mac RS-422 ports are backwards compatible with RS-232, dumb cables work fine. No Mac users were buying special RS-422 modems back in the day, we all used standard PC RS-232 modems and they worked fine with just a dumb cable. Even Apple's own serial printers were just RS-232.
  - ruslan 2y ago
    You are right, but it's possible to connect RS-422 to RS-232 using just proper wiring [1]. Basically, same three wires and one loop wire for RX+ to ground. It's not reliable and not recommended, but works and would solve the problem. :-) 1. https://stratusengineering.com/rs232-rs422485-conversion-cable-connection-requires-no-external-electronics-power/ https://stratusengineering.com/rs232-rs422485-conversion-cab...
tfvlrue 2y ago
Author here. It's a good question. It probably does, but I admit I'm not familiar with Zmodem. I don't recall finding a terminal application installed on the laptop, but maybe I just wasn't looking hard enough.
- fuzzfactor 2y ago
  Before they had built-in phone modems, the CPU communicates with a COM port for general I/O to the outside world. COM port is just serial digital data transfer by RS-232 standard, unlike the parallel (printer) port, the COM port is very robust because the RS-232 standard requires the ability to short or improperly connect any of the pins to at least +/- 12VDC without doing any damage. You connect two mainframes or personal computers' COM ports together using a "null modem" (crossover) cable having a common ground connection and with each's data transmit wire (pin 2) connected to the other's data receive wire (pin 3). You have to set the same baud rate, word length, parity, and number of stop bits on each device. Handshaking lines can often be considered "optional" so many of the cables only have these 3 wires. However using the comm app you may have to virtually enable a handshake line or two on each computer if the extra wires are not there and the devices are troublesome for some reason. The terminal app or related program will usually be where you get to the communication settings, and once the terminal at each end of the communication cable is correct, then each person can type to the other in real time, perhaps simultaneously depending on "duplex" setting. Very much like an antique teletype machine, COM ports are also referred to as tty's. With a GUI there should be a drop-down menu where you can set the receiving terminal to collect all following data from that point, into a file which you should be able to name yourself and store where you would like after the transfer finishes. At the sending terminal you click the corresponding button to open the selection window so you can browse for the file you want to send out on the COM port. To do it over the phone, the device at each end would then add an external modem plugged into the COM port. Then you can connect computers to the outside world using a phone cable. The modem is what detected the dial tone and dialed your target's number on the public phone network from your land-line location, as well as doing the audio modulation of your data so it would go well over the phone line. Modems started out pretty dumb and it was years before "smart" modems became common, but almost all of them responded to what is known as special AT commands. Somewhat specific set of AT's for different manufacturers and vintages. Receiving the ATD command followed by the target phone number, the modem would open the phone line, listen for a dial tone, then autodial the digits you had provided. If the other party responded then the intercommunication would begin. But if you're just connecting two computer modems together in the same office without going over land lines there is no dial tone and no voltage being provided by the phone company either. The voltage is well covered with the battery arrangement shown, but a different AT command must be used on the sending modem so it will proceed to negotiate communication without the dialing process. IOW all personal devices had com ports and that's what you used at first, not everybody was good with the cables and settings though so it never became very common knowledge. After built-in phone modems began to appear, devices retained COM ports in addition for a period of time before they started becoming more rare. Once there was no more COM port exposed to the user, yes you can go directly from modem-to-modem, but it's always another layer of complexity in addition to the underlying COM-to-COM foundation. Remember terminals produce ASCII text through your designated COM port when typing but it's just binary data when sending files. You can send a Windows EXE file to a MAC for storage and it will be a faithful copy but naturally it's not made to actually execute on the MAC.
oneplane 2y ago
You can indeed use xmodem or zmodem, and use a macbinary encoding to transfer any file you want in either direction. Does require you to have something that can receive over serial on the PowerBook. ClarisWorks could definitely do it, but office probably has exactly the same 'receive document' feature. Alternatively, you can use the serial port to 'print' to, and just capture the serial output. It's essentially just unidirectional text transfer but that's enough for what the author intended to do. On the other hand, faxing and OCR'ing is pretty cool.
- deleted 2y ago
  [deleted]
- EvanAnderson 2y ago
  > Alternatively, you can use the serial port to 'print' to, and just capture the serial output. I've done this to recover data from a number of old systems. It's a great way to get at old data. I've also done this to get data out of proprietary databases. As long as there's a report that gets the data you want it becomes just a parsing problem.
- dredmorbius 2y ago
  Many moons ago I'd bootstrapped a Linux install on a circa-1990 laptop which afforded a floppy drive, serial, and parallel ports, but no innate networking (a 32-bit PCMCIA network card was later possible but required drivers and/or kernel support to be compiled). I'd pieced together the install by splitting a tar.gz across multiple floppy transfers, then enabled SLIP and zmodem which permitted copying uu-encoded files for further support, then SLIP and PLIP. The latter was particularly useful as I could sustain multiple simultaneous network connections: both an SSH session and scp'ing across files for further support, rather than running a console under minicom. SLIP was bound at somewhere around 9600 AFAIR, fine for a terminal session, but cramping my style for file transfers. (It may have been faster, 38,400 and 56k are available modem rates.) PLIP IIRC was at or approaching Mb/s speeds, which was (comparatively) blazing. Though the sheer audacity of copy-pasting uuencoded files through minicom had a certain coolness factor.
- flomo 2y ago
deleted 2y ago
[deleted]
thebeardisred 2y ago
Thanks for mentioning {X,Y,Z}modem. I think folks forget that it still has modern uses.
- implements 2y ago
  There’s also https://en.wikipedia.org/wiki/Kermit_(protocol) https://en.wikipedia.org/wiki/Kermit_(protocol) (We used back in the day to move files between PDP11s and PCs - it was the original “anything to anything” file transfer program)
- tsegers 2y ago
  I still use it regularly in 2024 to load data onto embedded devices running U-Boot. It saves me a network cable if one is not otherwise required.
  - ruslan 2y ago
    U-Boot supports Zmodem ?
    - ale42 2y ago
      EDIT: actually not ZModem, but it supports X/YModem -- source code, despite the comment at its beginning, finally says "Sorry, zModem not available yet" yes and also X/Ymodem, see source code: https://elixir.bootlin.com/u-boot/latest/source/common/xyzModem.c https://elixir.bootlin.com/u-boot/latest/source/common/xyzMo... extremely useful feature (I used xmodem in the past, if I remember well)
      - ruslan 2y ago
        Did not know that. Indeed it's very useful. Thank you!
  - olyjohn 2y ago
    I just had to update the firmware my HF radio using xmodem protocol. Tons of modern ham radio gear still using serial data... even the modern ones that connect to your PC via USB, still just a USB->serial device built in.

by ruslan 2y ago

gcp123 2y ago

Yes, it had those ports. Just like Kevin McCallister could've called the police in Home Alone, I think the author preferred this to become an extraordinary story more than the simplest possible solve.

perakojotgenije 2y ago

That's the first thing that came to my mind. I remember connecting two laptops using LPT or COM cable and transferring files using norton commander (if I remember correctly) 30 years ago.

rvense 2y ago

Apple used 8-pin mini DIN connectors for serial. The author might not have had the right cable.

hi-v-rocknroll 2y ago
A Farallon EtherWave provides Ethernet directly.
ruslan 2y ago
There are plenty of mini-DIN connectors and serial cables for mac on ebay. You need just three wires for serial line to work. I would strip the wires and plug them in without any connector. :)
inferiorhuman 2y ago
Classic macs had RS-422 not RS-232 ports so you'll need more than just a dumb cable to get it working with a PC.
- kalleboo 2y ago
  The Mac RS-422 ports are backwards compatible with RS-232, dumb cables work fine. No Mac users were buying special RS-422 modems back in the day, we all used standard PC RS-232 modems and they worked fine with just a dumb cable. Even Apple's own serial printers were just RS-232.
- ruslan 2y ago
  You are right, but it's possible to connect RS-422 to RS-232 using just proper wiring [1]. Basically, same three wires and one loop wire for RX+ to ground. It's not reliable and not recommended, but works and would solve the problem. :-) 1. https://stratusengineering.com/rs232-rs422485-conversion-cable-connection-requires-no-external-electronics-power/ https://stratusengineering.com/rs232-rs422485-conversion-cab...

tfvlrue 2y ago

Author here. It's a good question. It probably does, but I admit I'm not familiar with Zmodem. I don't recall finding a terminal application installed on the laptop, but maybe I just wasn't looking hard enough.

fuzzfactor 2y ago
Before they had built-in phone modems, the CPU communicates with a COM port for general I/O to the outside world. COM port is just serial digital data transfer by RS-232 standard, unlike the parallel (printer) port, the COM port is very robust because the RS-232 standard requires the ability to short or improperly connect any of the pins to at least +/- 12VDC without doing any damage. You connect two mainframes or personal computers' COM ports together using a "null modem" (crossover) cable having a common ground connection and with each's data transmit wire (pin 2) connected to the other's data receive wire (pin 3). You have to set the same baud rate, word length, parity, and number of stop bits on each device. Handshaking lines can often be considered "optional" so many of the cables only have these 3 wires. However using the comm app you may have to virtually enable a handshake line or two on each computer if the extra wires are not there and the devices are troublesome for some reason. The terminal app or related program will usually be where you get to the communication settings, and once the terminal at each end of the communication cable is correct, then each person can type to the other in real time, perhaps simultaneously depending on "duplex" setting. Very much like an antique teletype machine, COM ports are also referred to as tty's. With a GUI there should be a drop-down menu where you can set the receiving terminal to collect all following data from that point, into a file which you should be able to name yourself and store where you would like after the transfer finishes. At the sending terminal you click the corresponding button to open the selection window so you can browse for the file you want to send out on the COM port. To do it over the phone, the device at each end would then add an external modem plugged into the COM port. Then you can connect computers to the outside world using a phone cable. The modem is what detected the dial tone and dialed your target's number on the public phone network from your land-line location, as well as doing the audio modulation of your data so it would go well over the phone line. Modems started out pretty dumb and it was years before "smart" modems became common, but almost all of them responded to what is known as special AT commands. Somewhat specific set of AT's for different manufacturers and vintages. Receiving the ATD command followed by the target phone number, the modem would open the phone line, listen for a dial tone, then autodial the digits you had provided. If the other party responded then the intercommunication would begin. But if you're just connecting two computer modems together in the same office without going over land lines there is no dial tone and no voltage being provided by the phone company either. The voltage is well covered with the battery arrangement shown, but a different AT command must be used on the sending modem so it will proceed to negotiate communication without the dialing process. IOW all personal devices had com ports and that's what you used at first, not everybody was good with the cables and settings though so it never became very common knowledge. After built-in phone modems began to appear, devices retained COM ports in addition for a period of time before they started becoming more rare. Once there was no more COM port exposed to the user, yes you can go directly from modem-to-modem, but it's always another layer of complexity in addition to the underlying COM-to-COM foundation. Remember terminals produce ASCII text through your designated COM port when typing but it's just binary data when sending files. You can send a Windows EXE file to a MAC for storage and it will be a faithful copy but naturally it's not made to actually execute on the MAC.

oneplane 2y ago

You can indeed use xmodem or zmodem, and use a macbinary encoding to transfer any file you want in either direction. Does require you to have something that can receive over serial on the PowerBook. ClarisWorks could definitely do it, but office probably has exactly the same 'receive document' feature. Alternatively, you can use the serial port to 'print' to, and just capture the serial output. It's essentially just unidirectional text transfer but that's enough for what the author intended to do. On the other hand, faxing and OCR'ing is pretty cool.

deleted 2y ago
[deleted]
EvanAnderson 2y ago
> Alternatively, you can use the serial port to 'print' to, and just capture the serial output. I've done this to recover data from a number of old systems. It's a great way to get at old data. I've also done this to get data out of proprietary databases. As long as there's a report that gets the data you want it becomes just a parsing problem.
dredmorbius 2y ago
Many moons ago I'd bootstrapped a Linux install on a circa-1990 laptop which afforded a floppy drive, serial, and parallel ports, but no innate networking (a 32-bit PCMCIA network card was later possible but required drivers and/or kernel support to be compiled). I'd pieced together the install by splitting a tar.gz across multiple floppy transfers, then enabled SLIP and zmodem which permitted copying uu-encoded files for further support, then SLIP and PLIP. The latter was particularly useful as I could sustain multiple simultaneous network connections: both an SSH session and scp'ing across files for further support, rather than running a console under minicom. SLIP was bound at somewhere around 9600 AFAIR, fine for a terminal session, but cramping my style for file transfers. (It may have been faster, 38,400 and 56k are available modem rates.) PLIP IIRC was at or approaching Mb/s speeds, which was (comparatively) blazing. Though the sheer audacity of copy-pasting uuencoded files through minicom had a certain coolness factor.
flomo 2y ago

deleted 2y ago

[deleted]

thebeardisred 2y ago

Thanks for mentioning {X,Y,Z}modem. I think folks forget that it still has modern uses.

implements 2y ago
There’s also https://en.wikipedia.org/wiki/Kermit_(protocol) https://en.wikipedia.org/wiki/Kermit_(protocol) (We used back in the day to move files between PDP11s and PCs - it was the original “anything to anything” file transfer program)
tsegers 2y ago
I still use it regularly in 2024 to load data onto embedded devices running U-Boot. It saves me a network cable if one is not otherwise required.
- ruslan 2y ago
  U-Boot supports Zmodem ?
  - ale42 2y ago
    EDIT: actually not ZModem, but it supports X/YModem -- source code, despite the comment at its beginning, finally says "Sorry, zModem not available yet" yes and also X/Ymodem, see source code: https://elixir.bootlin.com/u-boot/latest/source/common/xyzModem.c https://elixir.bootlin.com/u-boot/latest/source/common/xyzMo... extremely useful feature (I used xmodem in the past, if I remember well)
    - ruslan 2y ago
      Did not know that. Indeed it's very useful. Thank you!
- olyjohn 2y ago
  I just had to update the firmware my HF radio using xmodem protocol. Tons of modern ham radio gear still using serial data... even the modern ones that connect to your PC via USB, still just a USB->serial device built in.