Image Map Image Map
Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: EGA monitor on Tandy 1000 EX

  1. #1

    Default EGA monitor on Tandy 1000 EX

    Wondering if an EGA monitor will work on a Tandy 1000 EX, from what I understand the Tandy has enhanced graphics meaning it should be close to EGA ?

  2. #2
    Join Date
    Aug 2006
    Location
    Chicagoland, Illinois, USA
    Posts
    6,425
    Blog Entries
    1

    Default

    The EGA monitor will work, but you'll be limited to Tandy 1000 graphics resolutions and colors (ie. you won't magically get EGA 640x350 graphics, only CGA graphics and the extra Tandy 160x200x16, 320x200x16, and 640x200x4 modes). EGA monitors were engineered to connect to CGA cards, and the Tandy connection is the same.
    Offering a bounty for:
    - A working Sanyo MBC-775, Olivetti M24, or Logabax 1600
    - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)

  3. #3
    Join Date
    May 2011
    Location
    Outer Mongolia
    Posts
    2,231

    Default

    One possible caution: An EGA monitor uses all 9 pins in the standard connector when running in EGA mode, while in a standard CGA pinout pin 7 should be "N/C", IE, not connected. The Tandy 1000 EX has a weird quirk in which pin 7 is connected internally to the same output driver as pin 4, the green output driver. This is apparently to support a mostly undocumented "mono" mode that isn't really fully implemented on these machines. (Pin 7 is the video drive pin for MDA monochrome monitors, but the 1000 EX doesn't support the scan rate to drive one of those so it's not really clear what Tandy was thinking.) Pin 7 is the secondary "Blue" driver on EGA. An EGA monitor *should* ignore any input on that pin when it's running at the CGA scan rate, but just to be safe I'd suggest connecting the EGA monitor to the Tandy with a cable that has pin 7 pulled out.

    That same pin 7 thing breaks compatibility between the 1000 EX/HX and some Commodore 1084-family monitors, again, unless you cut it, because those monitors use that pin for a composite sync input with results in green essentially getting shorted out.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  4. #4

    Default

    Are we talking about possibly killing the Tandy or the monitor ? How could I remove the 7 pin ?

  5. #5
    Join Date
    Aug 2006
    Location
    Chicagoland, Illinois, USA
    Posts
    6,425
    Blog Entries
    1

    Default

    Neither would be killed, but you'd get incorrect output on the monitor.
    Offering a bounty for:
    - A working Sanyo MBC-775, Olivetti M24, or Logabax 1600
    - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)

  6. #6
    Join Date
    May 2011
    Location
    Outer Mongolia
    Posts
    2,231

    Default

    If your cable has all pins present you can probably just use a set of needle-nose pliers to break it off. (The jack on the computer is female, so you'd be doing this on the cable) Or with some connectors you could simply apply enough pressure to shove it down enough it doesn't engage. Or if the cable has one of those hoods you can unscrew to get to the connector you can take that off and snip the wire going to pin 7... plenty of options.

    And yeah, it probably won't permanently kill anything (if it has any effect), but it could either cause the monitor to display incorrect colors because that pin is being driven when it shouldn't be, or, like what happens in the case of those Commodore 1084s, the pin being grounded out effectively "kills" the green signal so any color that depends on green will be absent or incorrect.

    It may do nothing to have it attached because I *think* EGA monitors are hardwired to only honor pin 6 of the primary color "second bit" to use as intensity when running at the 200 line scan rate, but it's possible it might still take input on any of the secondary lines as intensity, in which case some colors *will* look wrong with that 4-7 bridge. Dunno, don't have an EGA monitor around to try.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  7. #7
    Join Date
    Aug 2006
    Location
    Chicagoland, Illinois, USA
    Posts
    6,425
    Blog Entries
    1

    Default

    To clarify, do **NOT** break the pin off of the cable directly attached to the monitor! Use a secondary straight-through cable, and sacrifice the pin on that one, which will make it a "tandy adapter cable" to the original cable.
    Offering a bounty for:
    - A working Sanyo MBC-775, Olivetti M24, or Logabax 1600
    - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)

  8. #8
    Join Date
    May 2011
    Location
    Outer Mongolia
    Posts
    2,231

    Default

    Quote Originally Posted by Trixter View Post
    To clarify, do **NOT** break the pin off of the cable directly attached to the monitor!
    Yes, definitely don't do that if the cable is captive to the monitor.

    So far as I can recall all the CGA/MDA/etc-era monitors I ever owned had removable cables so I didn't even think of that, but maybe I was just lucky.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  9. #9
    Join Date
    Sep 2008
    Location
    SE MI
    Posts
    4,661
    Blog Entries
    6

    Default

    Don't cut any pins. I used to use a piece of electrical tape over pin 37 on my Tandy DP-130 printer cable in order to make it usable on an IBM clone machine. You can cut a small bit of tape and carefully fit it over the pin in question - no need to modify any further. It might take a little practice to get it just right.
    Surely not everyone was Kung-fu fighting

  10. #10

    Default

    Would this cable DB-9 extension cable work ?

    https://www.cdw.ca/product/tripp-lit...b9f-6ft/622341

    Its branded as a "DB9 Serial or CGA Monitor Extension Cable" and appears to be 9 pin.
    So the procedure would be to cut the number 7 pin and plug that into the Tandy?

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •