I just came across this today, it looks like work that came about around
January 2024 by Mattis Land. Mattis, not sure if you're active here, but
this is really great work!
The emulator code is here:
https://github.com/MattisLind/DP2200/
An Unlisted demo of the emulator in action is here (running some CTOS
software):
https://www.youtube.com/watch?v=XfsMBhP13ww
Might this CTOS be the only operating system fit on an audio
cassette tape?
-Steve
Hi Ali,
I just replied to you through the vcfed forum. My posting is being moderated
(likely because I'm an infrequent poster) but I am interested in your HP
2563C printer.
Stan
I asked this before a few years ago but didn't come to a firm conclusion. The two parts are shown in this picture: https://rjarratt.wordpress.com/wp-content/uploads/2023/12/img_20231221_1123…
They are from a VT100 Monitor board. There is no schematic for my version of the board, but a related schematic is on p58 of this schematic: https://bitsavers.org/pdf/dec/terminal/vt100/MP00633_VT100_Schematic_Feb82.…. They are labelled Q414 and CR406, but the Feb 82 revision uses a different board and those two parts are in TO-220 packages rather than TO-3 as here..
I have removed both of them and tested them with a DMM. Neither of them measure as two diodes, they do not measure open circuit in any direction, so either they are both faulty or they are not transistors (unlikely). I have found a spec for a 2SB411 at https://alltransistors.com/transistor.php?transistor=10279. This seems to be a germanium transistor. When I last asked about this I had a conversation with Tony Duell, who was very sceptical that these could be germanium transistors, so naturally I am very doubtful that they are 2SB411 transistors. However, in the schematic Q414 is shown as NPN, the 2SB411 is PNP and this seems to match the way the part is connected on my board (Collector to HORIZ GND). I am working on a reverse engineered schematic.
Can anyone tell me what these components are so I can find a datasheet for them? Better still a suggested replacement would be really helpful, especially if they are 2SB411s because they seem to be hard to find.
Thanks
Rob
I find my collection of random old cards overflowing and I have picked
out six random PCI/AGP cards on the offchance anyone is interested
- Hauppauge PCI WinTV
- ES1371 AudioPIC (x 2)
- PCI Audio/modem card
- ATI AGP Rage Pro 109-73100-02
- ATI Radeon 9550 128M AGP
Images at https://postimg.cc/gallery/Y7PRkCG
Are the cards of any interest to people? (for the price of postage or
collection from London, UK :)
I may also have a phenom 9550 with its motherboard, some and a
selection of PCI plus IDE/SATA network cards - let me know if I should
go digging...
David
At 06:17 AM 2/6/2026, Christian Liendo via cctalk wrote:
>https://tinney.net/in-memoriam
>
>Robert Frank Tinney, of Washington, Louisiana, passed away peacefully
I remember meeting him at a COMDEX or maybe a West Coast Computer Fair
once upon a time. He was selling prints. I recognized him. His booth
wasn't getting the traffic it deserved!
- John
On 2026Feb 2,, at 11:00 PM, Rob Jarratt <robert.jarratt(a)ntlworld.com> wrote:
>
> I forgot to reply to this one. Thanks Brent.
>
> Of particular interest is the description of how the monitor board is supposed to work in the VT180 TM at page 6-102. When I have time I will check it carefully, I think there may be clues about Q414. Interestingly the intro says that horizontal section is not intuitively understandable from an examination of the schematic and it is a likely candidate for failure because of high stresses in the components.
I forgot some th-of-op was also included there, and then found it again tonight in another document:
vt100.net <http://vt100.net/> has a work-in-progress html version of some VT100 Technical manual:
https://vt100.net/docs/vt100-tm/ <https://vt100.net/docs/vt100-tm/>
There doesn’t seem to be a document date there but Chapter 4 has that th-of-op section on the Elston monitor:
https://vt100.net/docs/vt100-tm/chapter4.html <https://vt100.net/docs/vt100-tm/chapter4.html>
Section 4.8
Neither of course has the schematic, but notably these th-of-op sections reference component IDs that match the PCB & your RE'd schematic, and the small th-of-op diagrams do show Q414 as PNP.
The T403 pin numbers there differ from your labeling as Digital/Elston viewed it as 6-pin with 1 & 5 absent, rather than 4-pin.
Your pics show what appear to be some date codes from 1979.
The vt100.net <http://vt100.net/> website is aware of other field printsets from 1979:
https://vt100.net/manx/part/dec/mp-00633-00/ <https://vt100.net/manx/part/dec/mp-00633-00/>
but they also cannot find them.
So it does appear that, in addition to the Ball monitors, there were two versions of the Elston monitor for the VT100:
- one from 1979 with PNP HOT,
- one from 1982 modified to NPN HOT (along with other mods) (per MP00633_VT100_Schematic_Feb82.pdf)
Double-checking with the pics, your schematic looks correct to me regarding the HOT circuit.
Looks like the board could be modified for NPN with 1 ~ 3 trace cuts depending on how one went about heatsinking the HOT.
Or use the search specification selectors on sites like Digikey or Mouser to find an adequate hi-V PNP power transistor.
