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Thread: Why are standalone vintage ASCII keyboards so hard to find?

  1. #51
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    Quote Originally Posted by falter View Post
    That's kind of what I thought - but I've seen photos of original SCELBIs also with keyboards and no apparent connection to a monitor anywhere. So I wondered if there was in fact a way to utilize one.

    Won't be an issue for me.. I'm hoping to build the circuit described to interface my Mark-8 with my TVT (still not exactly sure how that works), but it piqued my curiosity.
    Interfacing a Mark-8 to a TVT or a teletype isn't that hard. The biggest issue is the software "driver". Mike Willegal and I had fun for a while going back and forth re-writing 8008 drivers for the Scelbi integrated into a monitor program. On the 8B wasn't so bad because you had the memory, but on the 8h with 1k of RAM there were a lot of programming tricks to save a byte here or there and still have room for programs. Mike focused on a bit bang'd serial version and I wired up a period UART setup which could handle dual serial interfaces to a single UART similar how the ADM-3 works. To be honest the UART didn't save me much as Mike wrote some pretty efficient code, but it did make a few things easier like hooking up an TI Silent ASR 733 and USB to serial adapter at the same time without an A/B switch so I could send code over from my MacBook and save it to tape on the ASR so I could reload it on the Scelbi from tape without the modern computer.

  2. #52
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    In the event.. I got this for about $100:

    https://rover.ebay.com/rover/0/0/0?m...2F202440236996

    I think that's a decent price (I seem to recall these going for $200+ in the past) and if I've done my homework this will definitely work with either my Poly or Big Board.

  3. #53

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    Quote Originally Posted by falter View Post
    In the event.. I got this for about $100:

    https://rover.ebay.com/rover/0/0/0?m...2F202440236996

    I think that's a decent price (I seem to recall these going for $200+ in the past) and if I've done my homework this will definitely work with either my Poly or Big Board.
    Ah, a George Risk 753 with Futaba switches. I have one.

    At least it looks close to the Poly-88 keyboard in this ad:

    BYTE Poly 88 ad.jpg

  4. #54
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    Quote Originally Posted by falter View Post
    In the event.. I got this for about $100:
    good job! I was hoping you'd see it.

  5. #55

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    It should work with the Poly88. It may have an issue with the System88. I recall, the word processor code needed a control @ key ( not sure if there is a key combo for that ). I recall modifying the firmware for a Franklin keyboard to include that decode.
    Dwight

  6. #56
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    Quote Originally Posted by Corey986 View Post
    Interfacing a Mark-8 to a TVT or a teletype isn't that hard. The biggest issue is the software "driver". Mike Willegal and I had fun for a while going back and forth re-writing 8008 drivers for the Scelbi integrated into a monitor program. On the 8B wasn't so bad because you had the memory, but on the 8h with 1k of RAM there were a lot of programming tricks to save a byte here or there and still have room for programs. Mike focused on a bit bang'd serial version and I wired up a period UART setup which could handle dual serial interfaces to a single UART similar how the ADM-3 works. To be honest the UART didn't save me much as Mike wrote some pretty efficient code, but it did make a few things easier like hooking up an TI Silent ASR 733 and USB to serial adapter at the same time without an A/B switch so I could send code over from my MacBook and save it to tape on the ASR so I could reload it on the Scelbi from tape without the modern computer.
    Yeah. I have this homebrew Z80 machine with 1KB. I mean, it's pretty useless. I don't know how people made stuff work with so little. And I think with the Mark-8 a lot of people didn't even go to 1K because of the expense. I actually have 9 of the original kit boards.. the original 6 plus 3 memory boards. Somebody was planning to go to the full 4K but then never did any of it. I've seen a few Mark-8s even with just 256 bytes, the first line of RAM installed on board. I have enough 1101s I think to to get to 3KB with the Mark-8 I'm building, but I don't know if I'll go that far. Don't know how many will be bad or how many I'll want to keep around as spares.

    I kind of wondered if you'd need a driver of some sort with the TVT and Mark-8. I didn't understand how the circuit they provide would allow the Mark-8 to understand info coming in from the TVT the keyboard and then direct a display to back to it.

  7. #57
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    Quote Originally Posted by falter View Post
    I kind of wondered if you'd need a driver of some sort with the TVT and Mark-8. I didn't understand how the circuit they provide would allow the Mark-8 to understand info coming in from the TVT the keyboard and then direct a display to back to it.
    Like Corey said, it is really no big deal. I cut my teeth on 8008 assembly. Back when you were working with the bare metal nothing was hid from you. There were no standard libraries that hid what was happening. Basically you have a loop in the program that reads the input port that the keyboard is connected to. In my case the keyboard strobe set bit 8, in the old world we only used 7 bits of the ASCII code. When bit 8 goes high I kept the byte and processed it. Until <enter> was pressed I would store the byte in an input buffer. Next I would output the same byte, striped of the 8th bit, to an output port where the TVT was connected. Magically the character would appear on the screen!

    The old TVT's were pretty dumb. Typically you are just writing to the display memory that is scanned continuously and the characters are displayed on the CRT. Much of the positioning logic was done on the actual computer.

    A few years back I designed a TVT board for my Mark 8. I interface it to three ports on the Mark 8. One to write characters, the other two to set the line and column. Once the x/y positions are set each character write will advance the cursor. http://i8008.net/MARK8/

    If you really want to understand how people did so much with so little I'd suggest downloading early Byte magazines. You can see the evolution of microcomputers. ALso go over to S100 Computers and look at the board manuals. It's really interesting.

    Once you get away from the paradigm of modern computers, languages, and operating systems your eyes will really be opened. I think few modern programmers today even grasp anything deeper than their high level languages. Personally, an understanding of these systems down to the chips makes you a much better engineer and developer.

    CHeers,

    len
    Spread the joy of Vintage Addiction

    -->www.chronworks.com/<--->www.i8008.net/<--

  8. #58
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    Quote Originally Posted by 8008guy View Post
    Like Corey said, it is really no big deal. I cut my teeth on 8008 assembly. Back when you were working with the bare metal nothing was hid from you. There were no standard libraries that hid what was happening. Basically you have a loop in the program that reads the input port that the keyboard is connected to. In my case the keyboard strobe set bit 8, in the old world we only used 7 bits of the ASCII code. When bit 8 goes high I kept the byte and processed it. Until <enter> was pressed I would store the byte in an input buffer. Next I would output the same byte, striped of the 8th bit, to an output port where the TVT was connected. Magically the character would appear on the screen!

    The old TVT's were pretty dumb. Typically you are just writing to the display memory that is scanned continuously and the characters are displayed on the CRT. Much of the positioning logic was done on the actual computer.

    A few years back I designed a TVT board for my Mark 8. I interface it to three ports on the Mark 8. One to write characters, the other two to set the line and column. Once the x/y positions are set each character write will advance the cursor. http://i8008.net/MARK8/

    If you really want to understand how people did so much with so little I'd suggest downloading early Byte magazines. You can see the evolution of microcomputers. ALso go over to S100 Computers and look at the board manuals. It's really interesting.

    Once you get away from the paradigm of modern computers, languages, and operating systems your eyes will really be opened. I think few modern programmers today even grasp anything deeper than their high level languages. Personally, an understanding of these systems down to the chips makes you a much better engineer and developer.

    CHeers,

    len
    I've never done programming in anything other than BASIC so this will be a real experience.

    I actually debated building my Mark-8 according to the Digital Group's specs in one of their packets, which includes a 'TV Typewriter' video card and the ability to warm boot. I thought that might be a fascinating avenue to explore... there are tons of straight up Mark-8 blinkenlight replicas up there. I have only seen one (original) Mark-8 fully built out to Digital Group's specs. Only problem is it would negate my intended purpose for the TVT.

  9. #59
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  10. #60
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    Quote Originally Posted by Al Kossow View Post
    Neat keyboard. Any idea as to the price?
    Spread the joy of Vintage Addiction

    -->www.chronworks.com/<--->www.i8008.net/<--

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