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Thread: Terminal Card for IBM compatibles

  1. #1

    Default Terminal Card for IBM compatibles

    So this post is some musings on a rainy day in SoCa on a wish list for a tool and maybe a start of discussion on production....

    I obviously have no hardware design experience so I am hoping that if it is a possibility one of the HW gurus like Sergey or Pearce_jj who have helped out the community so much will step up and do the real heavy lifting.

    The IBM PC never had real terminal capabilities (i.e. using a serial port to run stuff). Over the years people have attempted to add this capability with some degree of success. The PC Weasel 2000 was probably the most successful. More recently the XT-IDE BIOS has a options to boot over serial port. Other systems have had such capability built in (e.g. Sun, SGI, etc.) or have tool that almost achieve some of the same thing (ADT on the Apple II).

    Terminal capability would be great for people who have an older PC (or compatible) but may not have the appropriate monitor, KB, HDD or boot disks. It would also be great for trouble shooting as one could be down to just a MB. So what I am wondering is as follows. How easy/hard would it be to make an 8bit card that allows for the following as a minimum:

    1. 8-bit ISA Card
    2. Bootable BIOS w/ terminal capabilities (maybe from XT-IDE?)
    3. Free-DOS/ROM-DOS in ROM for full DOS capability to format disks, copy, fdisk, etc.
    4. 9pin and 25pin Serial port that is already setup as a null modem (so one can use a straight through serial cable)
    5. 16650 or better UART (bigger buffer/faster speeds)

    Would be nicer if we could also add:

    1. HW DX Suite built in (ala Supersoft LANDMARK ROM POST)

    Nicest would be to add
    1. A monochrome display emulator (like the PC Weasel 2000) so that the machine can have full terminal emulation. The Weasel used to a KB cable for pass through of KB input to the main system. I am wondering if it would be possible to do this with SW (i.e. directly place keystrokes in the host computers KB buffer).

    A deluxe version could add an RJ45 port and network capability so you could telnet into your vintage system from any other computer (although you can always connect the serial port to the LAN via 3rd part equipment like the Avocent series for RS232 to RJ45 terminals).

    So how easy it would be to built this? I know it is doable but can it be done on the same scale and ease as the XT-IDE project? Would it even have use for other people?
    Current Wish List: 1. IBM 7531 Industrial Series PC 2. NEC MultiSync XL (JC-2001) Monitor 3. Copy II PC Enhanced Option Board (the one with the toggle switch on the back) 4. MicroSolutions MatchPoint AND/OR UniDOS card 5. Compaq 14" VGA CRT Monitor (the one that came with the SystemPro)

    If you have any of the above for sale please PM me. Thank you!

  2. #2
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    Back in, what 1986, I worked with another fellow on an ISA card with some memory and a Z80 and assorted peripherals to provide remote monochrome capabilities via serial interface to a VT-100/220 terminal. It had two serial connections--one to a remote mainframe and the other to the VT220 terminal. You could, with various key combinations, swap between PC and remote mainframe or even split-screen the two. It worked well on an XT, but I suspect not on systems with faster ISA busses. I still have the card--and the firmware.

    What did it in were inexpensive packages like PC Anywhere and Carbon Copy.

  3. #3

    Default

    Quote Originally Posted by Chuck(G) View Post
    Back in, what 1986, I worked with another fellow on an ISA card with some memory and a Z80 and assorted peripherals to provide remote monochrome capabilities via serial interface to a VT-100/220 terminal. It had two serial connections--one to a remote mainframe and the other to the VT220 terminal. You could, with various key combinations, swap between PC and remote mainframe or even split-screen the two. It worked well on an XT, but I suspect not on systems with faster ISA busses. I still have the card--and the firmware.

    What did it in were inexpensive packages like PC Anywhere and Carbon Copy.
    Chuck,

    Exactly something like that would be great. In essence the PC Weasel did that but less as I believe the Weasel replaced the video card in the system so no split screen or anything fancy like that.

    The problem with the SW packages is that you already have to have a functioning and configured system. Not much use in getting a bare metal system up and running...
    Current Wish List: 1. IBM 7531 Industrial Series PC 2. NEC MultiSync XL (JC-2001) Monitor 3. Copy II PC Enhanced Option Board (the one with the toggle switch on the back) 4. MicroSolutions MatchPoint AND/OR UniDOS card 5. Compaq 14" VGA CRT Monitor (the one that came with the SystemPro)

    If you have any of the above for sale please PM me. Thank you!

  4. #4
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    The Tri-Link card that I described also replaced the standard video card. It addressed people who already had a terminal connected to a mainframe, but who also wanted to have PC functionality on their desk without an extra monitor and keyboard

    If the object was getting a bare metal system up and running, you could probably do something with a simple serial port and a BIOS ROM extension to poke around in the PC's innards and get things going.

  5. #5

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    Quote Originally Posted by Chuck(G) View Post
    The Tri-Link card that I described also replaced the standard video card. It addressed people who already had a terminal connected to a mainframe, but who also wanted to have PC functionality on their desk without an extra monitor and keyboard

    If the object was getting a bare metal system up and running, you could probably do something with a simple serial port and a BIOS ROM extension to poke around in the PC's innards and get things going.
    Chuck,

    Are you referring to this?

    At its most basic a srial port and ROM extension is all I'd want but if we can add some more features easily why not?
    Current Wish List: 1. IBM 7531 Industrial Series PC 2. NEC MultiSync XL (JC-2001) Monitor 3. Copy II PC Enhanced Option Board (the one with the toggle switch on the back) 4. MicroSolutions MatchPoint AND/OR UniDOS card 5. Compaq 14" VGA CRT Monitor (the one that came with the SystemPro)

    If you have any of the above for sale please PM me. Thank you!

  6. #6
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    That's it. 1984, well, time blurs after awhile. I was doing a lot of stuff back then; it's hard to keep the times straight.

  7. #7

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    Quote Originally Posted by Chuck(G) View Post
    That's it. 1984, well, time blurs after awhile. I was doing a lot of stuff back then; it's hard to keep the times straight.
    That's for true! One of the things I'm most sure of is that my rememberer is not as good as I remember it being. I think I remember that being called "recursion".
    "It's all bits on the bus, Cowboy! It's all bits on the bus!" -- Tom Beck, #1ESS Instructor, Southern Bell Opa Locka Training Center

  8. #8

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    Weird, I was just thinking about something similar. I think I brought this up before but the explanation Chuck(G) (I think) gave, of how to actually make it work, turned me off the idea. z80 CPU and all. Way too complex for me to do. Would love to see the design though.

    I was reading the thread on:
    http://www.vcfed.org/forum/showthrea...uccess-stories

    And the question of MDA was brought up. And then I came across this:
    http://pascal.sources.ru/graph/dcfg202.htm

    It's a very basic frame-grabber that connects to the parallel port. So I though could this be adapted to MDA, or indeed any TTL based graphics? I'm not entirely sure how to calculate the bandwidth of MDA, 1bit @ 18425 hz gives me 2303 Bps, is that right?

    I was thinking feed the h/v sync directly to the parallel ports D0/D1, and perhaps a serial-to-parallel shift register, to slow the ?color? signal down and use the remaining D2-D7 pins. I'm not sure if you would need some kind of phase locked loop system, to ensure you don't have drift. The document mentions problems with jitter. If you could get the raw data into a Tweener, you could then process it with OCR or for Hercules just pipe it to some video stream.

    The main advantage is that it is 100% transparent.

    Is this a fools errand?

  9. #9
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    If you're using an MDA, why bother with frame-grabbers? An MDA is just 80x25 text-only. It would seem to me to be far easier to send the raw text.

    Also, it depends on your tolerance to modern technology. Implementing the original terminal card scheme with a cheap MCU would be more than adequate today. We've come a long ways from the 4MHz Z80A. I love experimenting with the little $2 STM32F103 modules. I mean, a 72MHz 32-bit processor with 20KB RAM with USB, serial I/O, SPI, ADC and GPIO all on a single DIP PCB for $2-4, depending on quantity. How could anyone not like this?

  10. #10

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    Quote Originally Posted by mR_Slug View Post
    Weird, I was just thinking about something similar. I think I brought this up before but the explanation Chuck(G) (I think) gave, of how to actually make it work, turned me off the idea. z80 CPU and all. Way too complex for me to do. Would love to see the design though.
    mR_Slug,

    It really depends on I guess what you want to do. At its most basic I was musing about a card that would have a bios that could be accessed at boot and let you transfer a disk image via serial port and write said disk image. In many ways XT-IDE can accomplish this (i.e. you could boot an image over serial port and then write a disk image). Of course this requires you to have a number of things in place:

    1. A working system
    2. An appropriate monitor, kb, disk drives, and disks

    But XT-IDE can do so much more and is a more complex beast then this. In fact I do not know anyone who has gotten it to boot over serial. Not saying it can't be done. Just that my friends and I have not been successful... So a basic version of the terminal card would have a simplified BIOS with all the unnecessary code cut out of the BIOS (i.e. IDE device support) and having it auto invoke (i.e. if the card is in the system it will kick in before the FDD or HDDs and force interaction). The card would also have its own serial port (not necessarily visible to the rest of the system) wired in null modem config so that a novice would only have to provide a standard RS-232 cable to get going. Basically this would be more of a HW equivalent of ADT program for the Apple II computers then a true terminal card.

    So what happens when you don't have the right monitor? (i.e. your eBay bought 5150 comes with a MDA or HGC video card but you barely have a VGA CRT around) or KB or whatever? Then this doesn't really work well. Hence the expansion to a full terminal card.

    In this scenario the card would also let you interact with the system over the serial port so that all video and KB input would come from the remote system through a serial connection. Video would be limited to text of course but this is no big deal because at this point you are still just trying to get DOS up and running or doing some basic diagnostic. The PC Weasel 2000 that I linked to was essentially this - it replaced the video card in a system and rerouted I/O through the serial port.

    Of course the best of both worlds would be to combine both of the above ideas and expand them IMHO:

    The card when plugged in would take over as the first boot device, the system would boot into the ROM BIOS of the card, and would provide I/O through the serial port. Depending on how fancy you got the card could have 1. a full DOS system built in ROM so you could run simple text base programs, perform fdisk, format, write image files, etc., 2. maybe a diagnostic suite that would do simple tests (or users could supply their own commercial program ala Check it), 3. report POST codes and their meanings (from a lookup table), and 4. if we wanted to be real fancy an RJ45 port so the card could be connected to a router/switch/LAN and simply be "teleneted" into. The card should also be compatible the ROM POST diagnostic BIOS (found in other thread on this site) video output so that a dead/minimally working system could be tested over a serial port w/ot the appropriate monitor, KB, disk drives, etc.

    Again I was musing on a rainy day. Is it doable? I think so all the elements have been done before so pulling them together should be possible. Is it feasible? Well that's an entirely different question .
    Current Wish List: 1. IBM 7531 Industrial Series PC 2. NEC MultiSync XL (JC-2001) Monitor 3. Copy II PC Enhanced Option Board (the one with the toggle switch on the back) 4. MicroSolutions MatchPoint AND/OR UniDOS card 5. Compaq 14" VGA CRT Monitor (the one that came with the SystemPro)

    If you have any of the above for sale please PM me. Thank you!

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