According to history Windows 1 was introduced to the world on Nov. 20,
1985, 40 years ago, minus 2 days. Prior to this Windows was first announced
in 1983(vaporware) but…An even earlier development was Interface Manager.
What we have now is much more and ‘better’ but for classic computing I
still prefer WIN 3.1.
Happy computing.
Murray 🙂
I have an ST-251 42MB MFM hard disk drive.
The documentation says the drive is 512 bytes per sector. I don't know
if this is fixed (hard sectored) or not.
My problem is my operating system (OS/9 Level II) wants 256 bytes per
sector. The OMTI 20C-1 controller can handle that but I'm not sure if
the ST-251 can.
Does anyone know if the ST-251 can support 256 bytes per sector and/or
how to configure it for 256 bytes per sector?
Thank you,
Mike
(sending again from a different email address as I don't think my first
email got through, apologies if this is a duplicate)
I have a VT100 that I was working on a while back and then set aside for a
bit. I have started to look at it again. I have noticed that the Video Shift
Register, a 74S299, gets very hot, I can smell the heat and the chip gets
almost too hot to touch, reaching almost 40 celsius. I have a working VT102
for comparison and the same chip there does not get so hot (it reaches about
30 celsius). I have already tried replacing the chip, but the new one gets
equally hot.
I looked at the signals the chip is receiving and the one that stands out as
different is the CLK input (pin 12). It looks like this:
https://rjarratt.wordpress.com/wp-content/uploads/2024/04/vt100-74s299-clk-s
ignal.png. On the VT102 it looks like this:
https://rjarratt.wordpress.com/wp-content/uploads/2025/11/vt102-74s299-clk-s
ignal.png. It is much spikier on the VT100 and I was told at one point that
this could be the cause of the hot running for the chip. Is that a
reasonable assumption?
Assuming the spikes are the cause of the hot running. I am trying to see why
there is a difference. I have noticed that on the VT102 there is a 68R
resistor between the DC011 which produces the signal and the 74S299. You can
see this as R86 in the VT101 printset
https://bitsavers.org/pdf/dec/terminal/vt101/MP-01066-00C_VT101_Family_Field
_Maintenance_Print_Set_Apr82.pdf (p47 of the PDF). The VT100 printset dated
Feb 82
https://bitsavers.org/pdf/dec/terminal/vt100/MP00633_VT100_Schematic_Feb82.p
df shows an inductor L8 being used (PDF p17), but my VT100 does not have
this and so must be described by the March 80 printset
https://bitsavers.org/pdf/dec/terminal/vt100/MP00633_VT100_Mar80.pdf (PDF
p17).
Could the absence of L8 explain the spikier DOT CLK signal and the hotter
74S299?
Incidentally, I suspect that the flyback transformer on my VT100 has failed.
If anyone has a flyback transformer going spare, especially in the UK, then
I would love to hear from you.
Thanks
Rob
I'm looking for ancient versions of the VAX Workstation Software (VWS) for
my software collection and for my VAXstation I:
- V1.0
- V1.1
- V2.0
- V3.0
V1.0 (which was called "uVMS VAXstation I graphics/windowing softwarere"
back then) and V1.1 are the most wanted ones, because they are the only
ones that run on MicroVMS V4.0 for the VAXstation I.
Version 1.0 was shipped on two RX50s, labeled “VSI010 1/2” and “VSI010
2/2”; later versions grew bigger and from V2.0 onwards TK50s were used
besides RX50 floppies as well.
Best Regards,
Ulli
40 years ago this year Intel came out with the 80386 – 386 – or i386.
Either seems to be correct. What this meant was a memory address of 4GB,
far beyond what an average computer user would need or want, but was so
much more than previously(8086, 80286); ‘true’ multi-tasking which for the
average computer user didn’t mean all that much; and paging, which made
virtualization possible- experimenters were over-joyed! What all this
contributed to was the end of the classical/vintage-computing era. Whether
this began the time of open-source OS development is debatable!
Happy computing?
Murray 🙂
Via one of the articles about that Unix V4 tape I found this https://eylenburg.github.io/os_familytree.htm which is quite an impressive chart of operating systems old and new.
A few bits are clearly incorrect or missing; for example, P/OS and TRAX are both not there. I was going to mention them to the author of that chart but I don't actually know the correct placement. (Is P/OS an RSX-11/M or M+ derivative? I should know but don't.)
Neat to see RSX-15 mentioned as the ancestor of RSX-11/D. Did the earlier RSX-11 versions ever ship? I know I have seen traces of /A and/or /C...
The DOS-11 and RSTS entries aren't quite right either, I can send feedback for those.
Also, while VMS is reasonably listed as RSX-11/M derivative, I always thought that VAXElan was unrelated. Along the same lines, where would MicroPower/Pascal fit?
paul
It seems that nowadays you can't get *any* replacement for failing DEC
3639 aka 2N3639 transistors. All parts are obsolete and unobtanium, e.g.
2N3640, PN3640, MMBT3640 and so on.
So, what can be used instead? The most important electrical parameter is
the storage time. It needs to be *very* low, around 20-30 ns.
Does it mean that a failing PDP-8 will stay a dead PDP-8 from now on?
Christian
