Re: DEC VT20 boot device
> I didn't fully disassamble the program I have now done so; the -YK is _exactly_ the same as the -YA (the later ones, which are minorly different from what's in the manual), except that the HSR address (177550) has been replaced as the primary device address by that of DL11 #1, in the second block of DL11 addresses (175610). In other words, the ROM is prepared to load something in bootstrap loader format (which I have documented here: http://gunkies.org/wiki/PDP-11_Bootstrap_Loader the one program known in this format is the absolute loader) over the non-console serial line. Noel
Re: DEC VT20 boot device
> On Aug 11, 2019, at 7:45 PM, Eric Smith via cctalk > wrote: > > On Sun, Aug 11, 2019 at 1:18 AM Bob Smith via cctalk > wrote: > >> The VT20 design team was, iirc, John Kirk for the video, and me for >> the Unibus interface in the first version. The one with the slick >> one shown here, >> http://bitsavers.org/pdf/dec/terminal/vt20/vt20_2.jpg >> > > That looks pretty nice, since externally it just looks like a VT05 with > extra buttons. > > The vt20/b (photos in same directory), on the other hand, is one of the > ugliest terminals I've ever seen. It looks a bit like an early concept for what became the VT71. The terminals directory also shows a thing called VT21 which appears to be identical to the VT71. I wonder if the VT20/b and VT21 were engineering prototypes that were later released under the name VT71. paul
Re: DEC VT20 boot device
I worked on a lot of Xerox 820s, apparently that did the same job! On 11/08/2019 19:45, Eric Smith via cctalk wrote: On Sun, Aug 11, 2019 at 1:18 AM Bob Smith via cctalk wrote: The VT20 design team was, iirc, John Kirk for the video, and me for the Unibus interface in the first version. The one with the slick one shown here, http://bitsavers.org/pdf/dec/terminal/vt20/vt20_2.jpg That looks pretty nice, since externally it just looks like a VT05 with extra buttons. The vt20/b (photos in same directory), on the other hand, is one of the ugliest terminals I've ever seen. -- Nigel Johnson MSc., MIEEE VE3ID/G4AJQ/VA3MCU Amateur Radio, the origin of the open-source concept! You can reach me by voice on Skype: TILBURY2591 If time travel ever will be possible, it already is. Ask me again yesterday This e-mail is not and cannot, by its nature, be confidential. En route from me to you, it will pass across the public Internet, easily readable by any number of system administrators along the way. Nigel Johnson Please consider the environment when deciding if you really need to print this message
Re: DEC VT20 boot device
On Sun, Aug 11, 2019 at 1:18 AM Bob Smith via cctalk wrote: > The VT20 design team was, iirc, John Kirk for the video, and me for > the Unibus interface in the first version. The one with the slick > one shown here, > http://bitsavers.org/pdf/dec/terminal/vt20/vt20_2.jpg > That looks pretty nice, since externally it just looks like a VT05 with extra buttons. The vt20/b (photos in same directory), on the other hand, is one of the ugliest terminals I've ever seen.
Re: DEC VT20 boot device
> From: Paul Birkel > Apparently the VT20 used the M792-YK as its bootstrap; the Field Guide > is silent regarding the boot device and M792 documentation stops > earlier in the series of variants. An M792-YK recently sold on eBait; I didn't get it, but I did manage to get the seller to put up good photos of the board, so was able to dump the contents. I didn't fully disassamble the program, but it was clearly something serial line related. With the VT20 info, it's now clear what it was for. It should be pretty easy to fully disassamble, and work out the protocol. I have the dump of the contents if anyone has a use for them. Noel
RE: DEC VT20 boot device
>-Original Message-
>From: Jay Jaeger [mailto:cu...@charter.net]
>Sent: Saturday, August 10, 2019 11:02 PM
>To: Paul Birkel; General Discussion: On-Topic Posts
>Subject: Re: DEC VT20 boot device
>
>On 8/10/2019 1:56 PM, Paul Birkel via cctech wrote:
>> The DEC VT20 terminal apparently included a PDP-11/05 with a direct mapped
>> character display and was intended for text editing and typesetting. It
>> seems to have been followed by the VT21, and then VT71/VT72, all three based
>> on an LSI-11 (KD11-F). There's a real lack of documentation about these
>> online, although the VT72 does have a print set.
>>
>> Apparently the VT20 used the M792-YK as its bootstrap; the Field Guide is
>> silent regarding the boot device and M792 documentation stops earlier in the
>> series of variants.
>> ...
>> So . is the boot device in these systems the remote host via the serial
>> line? What protocol would that have been? Something native to Typeset-11
>> and DECset-11?
>>
>> paul
>
>I wonder if, maybe, it used the same protocol as the GT40, which also
>had a boot-over-serial line capability.
>
>JRJ
That's a promising lead! The GT40/42 User's Guide (EK-GT40-0P-002), Section
5.1 Communications Bootstrap/Read-Only Memory (ROM) describes a 256 word (GT40)
and 512 word (GT42) ROM, however it appears that the bootstrap loader portion
is intended to occupy 63 words which fits the M792 capacity (on the GT40 just
the absolute addresses 15700-15776 (base 8)).
Section 5.1.1 Bootstrap Loader describes the packed-and-serialized 6-bit "byte"
stream, including some nice diagrams. Section 5.1.2 Character Encoding
includes an illustrated example starting from a pictorialized 8-level paper
tape. Appendix D has an annotated (and unexpurgated) program listing of the
full GT40 ROM, including the loader and Figure D-1 Communications Bootstrap
Loader Flow Diagram. Program comments suggest that a PDP-10 was expected as
the host for a GT40. I imagine that the same expectation would have applied
for the earlier VT20?
Appendix E is similar, but for the "scrolling ROM - GT42" which appears to be a
VT05 emulation It includes more conventional loaders as well: RF11, RK11,
RC11, RP11, TC11, TM11, and paper tape. According to the program comments,
"the fearsome power of the 11" is brought to bear :->.
Both loaders are credited to Jack Burness.
If I understand the listings correctly then in the smaller VT20 ROM,
presumptively based on the same code, one would be expected to successfully
fall off the end of the ROM into freshly loaded code that signals back to the
host that a successful load has taken place. In the GT40 with the larger ROM
that acknowledgement ("SENDIT") is part of the ROM itself.
paul
Re: DEC VT20 boot device
Paul Birkel wrote: >>I wonder if, maybe, it used the same protocol as the GT40, which also >>had a boot-over-serial line capability. > > Section 5.1.1 Bootstrap Loader describes the packed-and-serialized > 6-bit "byte" stream I have the GT40 boot ROM assembled on a PDP-10 host and used for booting by SIMH. There is also a GTLOAD program which translates a PDP-11 binary on the PDP-10 host and sends it to the GT40.
Re: DEC VT20 boot device
> On Aug 10, 2019, at 2:56 PM, Paul Birkel via cctech > wrote: > > The DEC VT20 terminal apparently included a PDP-11/05 with a direct mapped > character display and was intended for text editing and typesetting. It > seems to have been followed by the VT21, and then VT71/VT72, all three based > on an LSI-11 (KD11-F). There's a real lack of documentation about these > online, although the VT72 does have a print set. > ... > Looking in a DEC "Options and Modules" listing I see VT20 bundles including > Typeset-11 and DECset-11, and it appears that the VT20 could be configured > with two displays & serial lines in a single 11/05. > > So . is the boot device in these systems the remote host via the serial > line? What protocol would that have been? Something native to Typeset-11 > and DECset-11? I've never heard of DECset-11, but I worked on Typeset-11 1978-1980. The VT71 was the standard high end terminal for that system. I saw a VT20 sitting in a corner of our lab, but it was collecting dust and I never saw it operate, or connected to anything. As far as I know, no trace of Typeset-11 or TMS-11 (same software pretty much, ported to a stripped-down IAS instead of RSX-11/D) have been preserved. It seems plausible that the download protocol would be DDCMP MOP mode, since that was a standard protocol supported by DEC for this purpose. But it could have been something custom as well -- it's not something I was ever exposed to. Yes, as far as I know the 11/05 controller for the VT20 could drive two independent displays. The VT71 had a single display, the control processor was built into the terminal case. I'm fairly sure the VT71 software was derived from that of the VT20, but just how close they were I do not know. paul
Re: DEC VT20 boot device
On 8/10/2019 1:56 PM, Paul Birkel via cctech wrote: > The DEC VT20 terminal apparently included a PDP-11/05 with a direct mapped > character display and was intended for text editing and typesetting. It > seems to have been followed by the VT21, and then VT71/VT72, all three based > on an LSI-11 (KD11-F). There's a real lack of documentation about these > online, although the VT72 does have a print set. > > > > Apparently the VT20 used the M792-YK as its bootstrap; the Field Guide is > silent regarding the boot device and M792 documentation stops earlier in the > series of variants. > > > > According to the VT72 print set, it used the MRV11-VC (M9942-YC; described > in the Field Guide as a "bootstrap/diagnostic module") for its bootstrap but > is also silent regarding the boot device. In interestingly, the Field Guide > also describes a MRV11-AA (M7942-TB) as a "M7942 with VT52 emulator, VT71 > bootstrap". > > > > For async. communications the VT20 used a DL11-B (M7800 (EIA)). the VT72 a > DLV11-F (M8028). > > > > Looking in a DEC "Options and Modules" listing I see VT20 bundles including > Typeset-11 and DECset-11, and it appears that the VT20 could be configured > with two displays & serial lines in a single 11/05. > > > > So . is the boot device in these systems the remote host via the serial > line? What protocol would that have been? Something native to Typeset-11 > and DECset-11? > > > > paul > > I wonder if, maybe, it used the same protocol as the GT40, which also had a boot-over-serial line capability. JRJ
Re: DEC VT20 boot device
The VT20 design team was, iirc, John Kirk for the video, and me for the Unibus interface in the first version. The one with the slick one shown here, http://bitsavers.org/pdf/dec/terminal/vt20/vt20_2.jpg The /05 based package was after my time, I don't remember much about how it was deployed. The boot device called using the boot strap board was variable, and I don't recall anything beyond an RK05 based system (booting the RK) for the versions in the lab on 1-2 in the mill. It was for the Typeset 11 team, and then the TypeSet.DecSet team/Product line. bob On Sat, Aug 10, 2019 at 2:56 PM Paul Birkel via cctech wrote: > > The DEC VT20 terminal apparently included a PDP-11/05 with a direct mapped > character display and was intended for text editing and typesetting. It > seems to have been followed by the VT21, and then VT71/VT72, all three based > on an LSI-11 (KD11-F). There's a real lack of documentation about these > online, although the VT72 does have a print set. > > > > Apparently the VT20 used the M792-YK as its bootstrap; the Field Guide is > silent regarding the boot device and M792 documentation stops earlier in the > series of variants. > > > > According to the VT72 print set, it used the MRV11-VC (M9942-YC; described > in the Field Guide as a "bootstrap/diagnostic module") for its bootstrap but > is also silent regarding the boot device. In interestingly, the Field Guide > also describes a MRV11-AA (M7942-TB) as a "M7942 with VT52 emulator, VT71 > bootstrap". > > > > For async. communications the VT20 used a DL11-B (M7800 (EIA)). the VT72 a > DLV11-F (M8028). > > > > Looking in a DEC "Options and Modules" listing I see VT20 bundles including > Typeset-11 and DECset-11, and it appears that the VT20 could be configured > with two displays & serial lines in a single 11/05. > > > > So . is the boot device in these systems the remote host via the serial > line? What protocol would that have been? Something native to Typeset-11 > and DECset-11? > > > > paul >
