Later Data General (D214/AViiON) keyboards?

[Chris Hanson via cctalk]

No, I'm not looking for old Dasher keyboards because "omg Severance."

I have a couple of Data General terminals (D214) and a couple of Data General 
UNIX workstations (AViiON, using m88k CPU) and only one keyboard. The one that 
uses an 8-pin DIN connector similar to the 5-pin IBM PC XT keyboard 
connector—and it speaks the same protocol over the same lines, but also has a 
couple extra features enabled by those extra 3 pins. (I believe the part number 
of the DG keyboard is 6348, but I'm not positive and can't find my reference at 
the moment.)

Does anyone have any more of the keyboards for D214 terminals or AViiON 
workstations that need a good home, a home which reunites them with appropriate 
hardware? I gather I can use XT-compatible keyboards with the AViiON systems at 
least, because of the compatibility I noted above, but I don't know about my 
terminals.

  -- Chris
  -- also always looking for anything else AViiON-related, 
hardware/software/docs
  -- and for docs for the D214 terminal too, of course

Re: Using tu58fs with RT11 5.7

[Jerry Weiss via cctalk]

On 5/5/22 8:30 PM, Douglas Taylor via cctalk wrote:
I wanted to try using tu58fs with a RT11 system running version 5.7 to 
transfer files in/out.


To my surprise RT11 5.7 retired the DD: device, a DD.MAC file is 
there, but it is unsupported.


(1) How do you compile a device driver file?  How do you link and 
install it?


(2) Has anyone done this?

(3) Is anyone using tu58fs with a RT11 5.7 system?

Doug

If you are using one of the distributed 5.7 monitors, try taking one 
from an earlier & similar version like 5.6.  The 5.7 changes did not 
impact handlers like this IIRC.


Of course if you want the build experience, check out the 5.6 device 
handlers manual.


  Jerry

Using tu58fs with RT11 5.7

[Douglas Taylor via cctalk]

I wanted to try using tu58fs with a RT11 system running version 5.7 to 
transfer files in/out.


To my surprise RT11 5.7 retired the DD: device, a DD.MAC file is there, 
but it is unsupported.


(1) How do you compile a device driver file?  How do you link and 
install it?


(2) Has anyone done this?

(3) Is anyone using tu58fs with a RT11 5.7 system?

Doug

Re: PCI floppy controller

[Chuck Guzis via cctalk]

On 5/5/22 17:44, Charles Dickman wrote:
> On Thu, Apr 21, 2022 at 10:34 PM Chuck Guzis  > wrote:
> 
> On 4/21/22 18:01, Charles Dickman wrote:
> > On Thu, Apr 21, 2022 at 8:02 PM Chuck Guzis via cctal
> > I was at that point and looking at DP3T switches to have an external
> > connection as well. DP3T switches are mess.
> 
> You could also bring the floppy cable out to a standard DC-37 connector
> on a bracket, then use a ABCD switchbox to select whatever external
> DC-37-cabled floppy drive you wanted.
> 
> 
> Where would you see those DC37 connectors for external floppies? I
> remember them, but not exactly where. 
> 
> I ended up getting a DPDT switch from the hardware store. A bit of
> ribbon cable, some hot glue and a couple pop-rivets and it works like a

Back in the bad old days, DC37F was the common way to bring out external
floppies on the ISA and MC bus.   Consider, for example, the original
5150 and 5160 4-floppy controller--there's that DC37 on the bracket.

All of the standard IBM external PS/2 floppy boxes used DC37-terminated
cables.  e.g. IBM 4869 among others.

Similarly, third party controllers such as the Micro Solutions
CompatiCard line and others all used DC37 connectors on the bracket.

I even have brackets with a DC37 attached to a smaller PCB with the
usual 34-pin header.

For a motion-picture example, see https://youtu.be/ATUFjPldvcg

--Chuck

Re: PCI floppy controller

[Fred Cisin via cctalk]

On Thu, Apr 21, 2022 at 10:34 PM Chuck Guzis  wrote:

You could also bring the floppy cable out to a standard DC-37 connector
on a bracket, then use a ABCD switchbox to select whatever external
DC-37-cabled floppy drive you wanted.

On Thu, 5 May 2022, Charles Dickman via cctalk wrote:

Where would you see those DC37 connectors for external floppies? I remember
them, but not exactly where.

I ended up getting a DPDT switch from the hardware store. A bit of ribbon
cable, some hot glue and a couple pop-rivets and it works like a charm.


DC37 was used for the external floppy on PC/5150 and XT/5160
For the PS/2, IBM had  an adapter to bring that out.



DC37 was also used on the Canon CX-VDO laser printers.
My Cordata used DC37, and so did my JLASER and EiconScript (Postscript 
and PCL) interface card,  so I had ANOTHER DC37 A/B/C/D switch for my 
laser printer.

Re: PCI floppy controller

[Charles Dickman via cctalk]

On Thu, Apr 21, 2022 at 10:34 PM Chuck Guzis  wrote:

> On 4/21/22 18:01, Charles Dickman wrote:
> > On Thu, Apr 21, 2022 at 8:02 PM Chuck Guzis via cctal
> > I was at that point and looking at DP3T switches to have an external
> > connection as well. DP3T switches are mess.
>
> You could also bring the floppy cable out to a standard DC-37 connector
> on a bracket, then use a ABCD switchbox to select whatever external
> DC-37-cabled floppy drive you wanted.


Where would you see those DC37 connectors for external floppies? I remember
them, but not exactly where.

I ended up getting a DPDT switch from the hardware store. A bit of ribbon
cable, some hot glue and a couple pop-rivets and it works like a charm.


> --Chuck
>
>
-chuck

Re: DEC H7822 power supply

[Peter Coghlan via cctalk]

Hi Maciej,

>
> Right, my notes indicate Nichicon PL parts might be problematic too, e.g. 
> one at 4700uF/10V on 5V output of the H7826 PSU.
>

What is H7826 used in?  I don't think I have any of those.

>
> I can confirm now Nichicon PF 47uF/35V parts to be the source of an issue 
> with my Bel Power.  All four leaked.  Thankfully I was able to fully 
> revive that PSU (now in 24/7 operation).
>

I got replacement capacitors for my POWER-ONE unit but I haven't managed
to obtain a replacement IRFPE50 chopper transistor yet.  I found a sort-of
local supplier that lists them but they have a EUR 30 minimum order and
they don't stock much other stuff I need or want :-(

>
> These are likely standard type parts.  I've yet to come across a low 
> impedance axial capacitor type.  I may have missed something of course.
>

I couldn't find any suitable axial replacements so I ended up using radials
which were roughly the same height as the width of the axials.

>
> >
> > > Heat dissipated by the cap itself under high ripple current never helps 
> > > and will surely speed up cap deterioration.  After all its service life 
> > > halvens with each 10°C temperature rise even with non-faulty parts.
> > >
> > 
> > When I was shopping for replacements, I was a bit alarmed to find that
> > the maximum specified "endurance" (whatever that is) I could find was
> > 5000 hours.  This isn't much more than a long life incandescent light bulb.
> 
>  Mind that it's at 105°C.  If you keep such caps operating at 65°C (which 
> is still rather hot), then endurance raises to 8h (~9 years continuous 
> use).
> 
>  Anyway try to chase replacements specified for at least 1h at 105°C.
> Nichicon HE/UHE and Panasonic FR seem suitable replacements for Chemi-con 
> SXF, Nichicon PL, surpassing old parts in terms of ESR/impedance/ripple 
> and dimension-wise.
>

When I was trying to order them, I found it hard to get anything suitable.
I ended up ordering 15 (out of 16 in stock at Mouser) Panasonic FC series
to do just three PSUs.

>
> I don't have any H7822 PSU.  Your experience with the H7821 is the same 
> as mine though (and I still need to figure out what's wrong with one which 
> still doesn't drive its power-good line active after recapping).
>

There is a 464 or 560 Ohm resistor near the capacitor in middle of the H7821
which has been damaged by leakage in several of my PSUs.  It is in series
with a thermistor mounted on a heatsink and as far as I recall it is part
of the fan control circuit.  It might also contribute to power-good though.
Other components could be damaged too or there could be goo lying under
some components.

>
> I used 
> Nichicon HE P/N UHE1E182MHD as the replacement for those.  There does 
> appear to be COVID-related shortage of this part (600 expected at Mouser 
> 15/03/2023, ugh!), which used to be readily available in large quantities 
> several years ago.  However Panasonic FR P/N EEUFR1E182 is available in a 
> small quantity (and is better).

I should grab some EEUFR1E182 before they disappear.

>
> I came across LXF parts in one H7826 only and they were clean, but I 
> chose to replace them as a precaution anyway as I've got stuck with trying 
> to repair a couple of broken H7826 PSUs already still not working after 
> cleaning the mess and replacing broken caps (mind that I'm a software 
> engineer with enough hassle to sort out on the software side already).
>

Sounds like it was better to not take a chance on them.

>
> I've seen leaks from SXF parts on the primary side too with the H7826, so 
> it is not that they only fail on the secondary side.  Also it is lower 
> frequency ripple that's more problematic, see frequency correction factors 
> for ripple current in datasheets, because impedance is higher at lower 
> frequencies.  That's an inherent property of capacitance.
>

That makes sense.

>
> > I replaced the five leaking capacitors on the upper board in my H7822,
> > disconnected the input to the lower board and moved the LED connection to
> > the upper board.  The machine powered up nicely afterwards, the fans spun
> > and the green LED came on after a short delay.  However, the diagnostic
> > LEDs all come on and stay on so it appears the CPU is being made aware that
> > the lower board is not functioning, even though I don't need it.  I should
> > to do some comparisons with a H7821 and see if I can work around this.  Or
> > maybe I could fit some not quite to specification electrolytics from the
> > junk box on the lower board, just to keep it happy?
> 
>  The symptom is exactly like with my broken H7821.  Check the power-good 
> signal (brown wire with the H7821, possibly likewise with the H7822).  It 
> should be driven high at the TTL level.
>

The wire in the same position as the brown one on a H7821 is purple on a H7822
and they both seem to have the same function.  I ended up temporarily fitting
a two 1000uF/25V capacitors on the lower board of my H7822 and reconnecting it

Re: The TRS-80 Journey Continues

[Mike Loewen via cctalk]

On Thu, 5 May 2022, Fred Cisin via cctalk wrote:

Although TRS-DOS didn't (until 6.0?, when TRS-DOS became rebranded LDOS), the 
after-market OS's supported DS and 80 track.

I don't remember how you needed to tell the OS that you had DS or 80 track.

But, once the OS knows, then the 55GFR, operating as a 55F, can, of course 
work.

Do you know how to tell your CP/M about DS and 80 track?


   Montezuma Micro CP/M (which Bill mentioned in a previous post) has a CONFIG 
utility to tell it what kind of drive is installed (5" or 8", number of 
tracks, number of sides, step rate). After that, there are literally dozens of 
disk formats to choose from, TRS-80 and many others.



Mike Loewen mloe...@cpumagic.scol.pa.us
Old Technology  http://q7.neurotica.com/Oldtech/

Re: The TRS-80 Journey Continues

[Fred Cisin via cctalk]

To test the suspect drive, you could connect it to a PC; with DS1 jumpered 
(instead of DS0), it should work as a "180K" (single sided "360K").


a PC with a floppy controller?  Wow, is that ever retro.


Besides FDC (especially for PCI :-), current Windoze doesn't seem to even 
know about single sided formats.   Can they  still handle "360K"?

Re: The TRS-80 Journey Continues

[Fred Cisin via cctalk]

The Teac FD-55GFR is a 96tpi drive.?? It can replace a 55G (1.2M), or a 55F 
(720K) depending on controller, but it still has a narrow head for doing 80 
tracks. It will have to be jumpered to run at 300RPM, not 360.


On Thu, 5 May 2022, Bill Gunshannon via cctalk wrote:

It has a jumper that leave that up to the controller.


But, the TRS-80 controller doesn't implement that signal; if the default 
of signal not present is 300 RPM, then it's all set, . . .



I used double sided as far back as my first Model III.  Even had a
full height Tandon 80 track double sided drive.  All I ever needed
was DOSPLUS or NEWDOS80.

That would be the Tandon TM100-4

Although TRS-DOS didn't (until 6.0?, when TRS-DOS became rebranded LDOS), 
the after-market OS's supported DS and 80 track.
I don't remember how you needed to tell the OS that you had DS or 80 
track.


But, once the OS knows, then the 55GFR, operating as a 55F, can, of 
course work.

Do you know how to tell your CP/M about DS and 80 track?



https://www.tim-mann.org/trs80faq.html#[19]
Discusses the drive selects and Mentions that you can use 55GFR, but 
doesn't give the details that you need?? (300/360 RPM, double stepping, 
etc.)



The 4P has the missing pins.  I never liked it and usually end out
putting in real cables and using Drive Select like it was intended.
At least until IBM won and the started making 3.5" drives without
any way to do drive select.


Good.The TRS-80 and IBM special cables were specifically because they 
didn't think that their own staff, and customers, could set drive-select 
properly on the drives.




But, more importantly, is the fault ONLY when format/verify?
Does it still READ disks that you already have?

Haven't really tried that.  Most of the disks I have are over
20 years old.  If it fails to read who's fault is it?  The drive
or the disk.


But, if it WORKS, . . .


One more possibility to pay attention, (you probably already know this, so 
sorry if saying it offends you), ...
You need to use 300 Oerstedt ("360K") diskettes.?? If you use 600 Oersted 
(1.2M) disks, they will seem to work, and then immediately, or VERY soon, 
lose their content.

Yeah, I knew about that.  I still have piles of real floppies laying
around.  :-)


The college purchasing agent was in bed with a supplier, and kept getting 
us Roytype HIGH DENSITY disks for our TRS-80 lab.  Even when we explicitly 
said not to substitute.

Re: The TRS-80 Journey Continues

[Bill Gunshannon via cctalk]

On 5/5/22 17:12, Fred Cisin via cctalk wrote:
Double sided drives in 4P shouldn't require anything more than software 
patches, to tell the OS (TRS-DOS, CP/M, etc.) that you have and want to 
use the other side.


The Model 3 and 4 disk controller (did the 4P use the same one??) 
supports double sided and uses pin32 as side select (as deity intended).


Pretty much.



Therefore, of course, using a drive that was jumpered for model 1 will 
require removing the pin 32 jumper that model 1 used as DS3.


While I have Model I's I never got into the modification stuff.  Today
I prefer to use things like MISE and FreHD (which also has a problem,
need to get in touch with Ian).



https://www.retrotechnology.com/herbs_stuff/Model4_35_Drives.pdf
(includes model 3/4 FDC pinout)


This includes the 300RPM jumpering for [SEVERAL VARIANTS OF] 55GFR:
http://www.oldskool.org/disk2fdi/525HDMOD.htm


Got that one.  But it seems to be mostly interested in making them
work on XT's.


The links on it to TEAC maanuals seem to no longer be supported by Teac.


The TEAC docs are still available but, again, even they seem
mostly interested in what it takes to use them with XT's and AT's.





To test the suspect drive, you could connect it to a PC; with DS1 
jumpered (instead of DS0), it should work as a "180K" (single sided 
"360K").


a PC with a floppy controller?  Wow, is that ever retro.

bill

Re: The TRS-80 Journey Continues

[Bill Gunshannon via cctalk]

On 5/5/22 16:50, Mike Katz via cctalk wrote:
If you use a 80 track (96 TPI) 5 1/4" drive to read 40 track (48 PTI) 
floppies that will work but if you write onto them they will not be 
readable in a 40 track drive any more.   The reason for this is that the 
had is half the width and when the 80 track drives writes to a 40 track 
written disk it only overwrites half of the track.  And when the 40 
track drive goes to read the data it sees nothing but noise because the 
two halves of the track are different.


Well known and documented back when we first started using 80 track
drives.



If you want to write floppies on an 80 track drive and read them on a 40 
track drive.  Magnetically erase the disks with a demagnetizer and then 
format the disk in the 80 track drive but double stepping the format.


I always erase floppies with my tape degauser before formatting.  Even
new disks usually have some pattern written on them.



Double stepping means writing track zero on physical track zero and then 
writing track 1 on physical track 2 and track 2 on physical track 4, etc.


This avoids the problem of tracks with different data on each half of 
the track.  The 40 track drive will only see the half track data.


Not all operating systems nor drivers can handle this.

Gimix Flex for the 6809 could handle this as a special configuration.

I'm sure you could get the greaseweasel to support this also.


I just got a GreaseWeazle.  Not impressed so far.



I hope this helps.



All information helps.

bill

Re: The TRS-80 Journey Continues

[Bill Gunshannon via cctalk]

On 5/5/22 16:28, Fred Cisin via cctalk wrote:

Next step...
Apparently mu original Tandon floppy has bought the farm.
Does anyone know what the jumper setting are for a
TEAC FD-55GFR-149 for the TRS-80 4P?
I tried the usual (like for a DEC RX-33) but that didn't
fly.  Every sector fails verify after a format.  I am sure
it's a jumper thing.



On 5/5/22 13:34, Mike Loewen via cctalk wrote:
    The FD-55GFR is a 1.2MB drive, double-sided. The Model 4P used 
360K drives (possibly Teac FD-55A), single-sided as installed at the 
factory. Are you sure that's the model number that was in your 4P?


On Thu, 5 May 2022, Bill Gunshannon via cctalk wrote:

I know it wasn't.  The original was a Tandon 50.  But the TEAC
FD-55GFR (in various flavors) was used in a lot of systems and
at least one website said they were used in the 4P.  It is an
extremely configurable drive that I have used for numerous DEC
systems (even the infamous RX50!)  I have several of them and
it should work just fine if I can find the magic jumper combination.


The Teac FD-55GFR is a 96tpi drive.  It can replace a 55G (1.2M), or a 
55F (720K) depending on controller, but it still has a narrow head for 
doing 80 tracks.   It will have to be jumpered to run at 300RPM, not 360.


It has a jumper that leave that up to the controller.



The FD-55B is double sided 48tpi ("360K"), and can be used in the 4P.
I don't know what, if anything needs to be done to use double sided in a 
4P (software patches? jumpers on disk controller?), but people DID.

It's a worthwhile modification to do.
The 4D, and the later models of the 4P used Teac double sided drives (55B?)


I used double sided as far back as my first Model III.  Even had a
full height Tandon 80 track double sided drive.  All I ever needed
was DOSPLUS or NEWDOS80.




On the other TRS80 models, the drive select jumpering was a little odd 
(although nor as odd as PC).  Like IBM, later, Radio Shack did not want 
to trust their people to be able to do the drive select jumpers.  So, 
they jumpered DS0, DS1, DS2, and used side select as DS3 on model 1!, 
then used a cable with the other drive selects removed.  So, with the 
stock cable, the first drive should work as DS0, but jumpers of DS1 and 
DS2 won't have any effect. https://www.tim-mann.org/trs80faq.html#[19]
Discusses the drive selects and Mentions that you can use 55GFR, but 
doesn't give the details that you need  (300/360 RPM, double stepping, 
etc.)


The 4P has the missing pins.  I never liked it and usually end out
putting in real cables and using Drive Select like it was intended.
At least until IBM won and the started making 3.5" drives without
any way to do drive select.




But, more importantly, is the fault ONLY when format/verify?
Does it still READ disks that you already have?


Haven't really tried that.  Most of the disks I have are over
20 years old.  If it fails to read who's fault is it?  The drive
or the disk.




One more possibility to pay attention, (you probably already know this, 
so sorry if saying it offends you), ...
You need to use 300 Oerstedt ("360K") diskettes.  If you use 600 Oersted 
(1.2M) disks, they will seem to work, and then immediately, or VERY 
soon, lose their content.


Yeah, I knew about that.  I still have piles of real floppies laying
around.  :-)

bill

Re: The TRS-80 Journey Continues

[Mike Loewen via cctalk]

On Thu, 5 May 2022, Bill Gunshannon via cctalk wrote:


On 5/5/22 13:34, Mike Loewen via cctalk wrote:

 On Thu, 5 May 2022, Bill Gunshannon via cctalk wrote:


 Next step...

 Apparently mu original Tandon floppy has bought the farm.
 Does anyone know what the jumper setting are for a
 TEAC FD-55GFR-149 for the TRS-80 4P?

 I tried the usual (like for a DEC RX-33) but that didn't
 fly.  Every sector fails verify after a format.  I am sure
 it's a jumper thing.


    The FD-55GFR is a 1.2MB drive, double-sided. The Model 4P used 360K
 drives (possibly Teac FD-55A), single-sided as installed at the factory.
 Are you sure that's the model number that was in your 4P?


I know it wasn't.  The original was a Tandon 50.  But the TEAC
FD-55GFR (in various flavors) was used in a lot of systems and
at least one website said they were used in the 4P.  It is an
extremely configurable drive that I have used for numerous DEC
systems (even the infamous RX50!)  I have several of them and
it should work just fine if I can find the magic jumper combination.

bill


   This article talks about settings for the FD-55GFR on page 41:

https://www.tim-mann.org/trs80/doc/TMQ%20Vol%20VII.i.pdf


Mike Loewen mloe...@cpumagic.scol.pa.us
Old Technology  http://q7.neurotica.com/Oldtech/

Re: The TRS-80 Journey Continues

[Fred Cisin via cctalk]

Double sided drives in 4P shouldn't require anything more than software 
patches, to tell the OS (TRS-DOS, CP/M, etc.) that you have and want to 
use the other side.


The Model 3 and 4 disk controller (did the 4P use the same one??) supports 
double sided and uses pin32 as side select (as deity intended).


Therefore, of course, using a drive that was jumpered for model 1 will 
require removing the pin 32 jumper that model 1 used as DS3.


https://www.retrotechnology.com/herbs_stuff/Model4_35_Drives.pdf
(includes model 3/4 FDC pinout)


This includes the 300RPM jumpering for [SEVERAL VARIANTS OF] 55GFR:
http://www.oldskool.org/disk2fdi/525HDMOD.htm
The links on it to TEAC maanuals seem to no longer be supported by Teac.



To test the suspect drive, you could connect it to a PC; with DS1 jumpered 
(instead of DS0), it should work as a "180K" (single sided "360K").

Re: Different font for second 1 on commodore 1571 drives (and others)

[Paul Koning via cctalk]

> On May 5, 2022, at 4:53 PM, Toby Thain via cctalk  
> wrote:
> 
> On 2022-05-05 1:43 p.m., John Robertson via cctalk wrote:
>> On 2022/05/05 10:26 a.m., Toby Thain via cctalk wrote:
>>> On 2022-05-05 1:03 p.m., John Herron via cctalk wrote:
 Someone at work pointed this out and I've never really thought about it. Is
 anyone here aware of the decision or reason to use a different 1 character
 for the last 1 vs the first 1?
>>> 
>>> Got a picture?
>> They may have run out of that original font if they were setting the type 
>> with something like Lettraset in the day.
> 
> An easy contemporary solution to that would have been to use a process camera 
> and make a copy.
> 
> However, based on this picture: 
> http://dunfield.classiccmp.org/c64/h/diskf.jpg , there *is* a good 
> typographic reason to cut the serif off the second '1'; if you didn't, it 
> would look ridiculous. The typographer's rule is, "If it _looks_ right, it 
> _is_ right," and the decal as shipped looks fine, typographically. We make 
> these slight "adjustments" all the time, it's a big part of the job 
> (especially for logos) - and reveals that a professional was involved. 
> Usually people don't even notice them, because that's the other rule of 
> typography.

There are other examples in our field of lettering that changes according to 
context: the font used by DEC on the PDP-11 handbook covers and a number of 
peripheral device panels.  The letters "t" come in "big loop" and "small loop" 
forms.  The big loop is used when there isn't another letter after; the small 
loop is used to avoid looking silly when another letter follows. Look at 
"digital equipment corporation" on the inside cover page of the PDP-11 
processor and peripheral handbooks, it shows it clearly.

I digitized that font and gave the same treatment to f, j and r, though I 
haven't seen those differentiated in the examples I looked at.

paul

Re: HP9825 internal ROM?

[Gregory Beat via cctalk]

Curious Marc has a complete set of YouTube videos on his restoration
of the HP 9825, due to Power Supply failure (no crowbar) damaging a number of 
ICs.

The Last video of the series shows fabricated of the PC Board for 
it’s missing Crowbar Circuit.
https://youtu.be/gIfJ30fPAOw

HP 9825 Crowbar Protection Circuit Project (Schematic, Parts, Gerbers, etc.
https://www.curiousmarc.com/computing/hp-9825-scientific-computer#h.xrov16yr03br

You can Order the PC Board from PCBWay
https://www.pcbway.com/project/shareproject/HP_09825_66552_Crowbar_Protecton_Circuit_for_the_HP_9825_Vintage_Calculator_a244bde6.html

greg
chicago
==
Date: Wed, 4 May 2022 16:40:13 -0400
From: Chris Zach
To: CCTalk mailing list
Subject: HP9825 internal ROM?

Question for the group: I'm working on a HP9825B here. 
First thing I did was take it apart, clean it, unplug all the power connections 
to the 
board and test the power supply. Supply is good (values below) so after 
checking the boards I put it together and powered it on.

Note: I can see the lack of a crowbar circuit on the +5 line and would 
be happy to install a crowbar circuit. Does anyone have a spare PCB 
board as otherwise I'd need to order at least three of them to build one.

Voltages are still good, however I get nothing on the display. The CAPS 
LOCK does light up the caps lock light and it's cleared by pressing 
Shift but that's about it.

Question: Is there supposed to be a ROM board or cartridge inside the 
unit by default? This one does not have one (the space between the front 
of the CPU board and the 4 card edges on the front). Perhaps that's the 
problem.

If so is it possible to build a board that can contain a more modern ROM 
with the system code on it?

Thanks!
Chris

Re: Different font for second 1 on commodore 1571 drives (and others)

[Toby Thain via cctalk]

On 2022-05-05 1:43 p.m., John Robertson via cctalk wrote:

On 2022/05/05 10:26 a.m., Toby Thain via cctalk wrote:

On 2022-05-05 1:03 p.m., John Herron via cctalk wrote:
Someone at work pointed this out and I've never really thought about 
it. Is
anyone here aware of the decision or reason to use a different 1 
character

for the last 1 vs the first 1?


Got a picture?


They may have run out of that original font if they were setting the 
type with something like Lettraset in the day.


An easy contemporary solution to that would have been to use a process 
camera and make a copy.


However, based on this picture: 
http://dunfield.classiccmp.org/c64/h/diskf.jpg , there *is* a good 
typographic reason to cut the serif off the second '1'; if you didn't, 
it would look ridiculous. The typographer's rule is, "If it _looks_ 
right, it _is_ right," and the decal as shipped looks fine, 
typographically. We make these slight "adjustments" all the time, it's a 
big part of the job (especially for logos) - and reveals that a 
professional was involved. Usually people don't even notice them, 
because that's the other rule of typography.


--Toby




I restore and sell the first coin operated video game - Nutting's 
Computer Space - and they mixed all sorts of fonts on the control panel. 
It was a pain to reproduce it!


John :-#)#

Re: The TRS-80 Journey Continues

[Mike Katz via cctalk]

If you use a 80 track (96 TPI) 5 1/4" drive to read 40 track (48 PTI) 
floppies that will work but if you write onto them they will not be 
readable in a 40 track drive any more.   The reason for this is that the 
had is half the width and when the 80 track drives writes to a 40 track 
written disk it only overwrites half of the track.  And when the 40 
track drive goes to read the data it sees nothing but noise because the 
two halves of the track are different.


If you want to write floppies on an 80 track drive and read them on a 40 
track drive.  Magnetically erase the disks with a demagnetizer and then 
format the disk in the 80 track drive but double stepping the format.


Double stepping means writing track zero on physical track zero and then 
writing track 1 on physical track 2 and track 2 on physical track 4, etc.


This avoids the problem of tracks with different data on each half of 
the track.  The 40 track drive will only see the half track data.


Not all operating systems nor drivers can handle this.

Gimix Flex for the 6809 could handle this as a special configuration.

I'm sure you could get the greaseweasel to support this also.

I hope this helps.

On 5/5/2022 3:28 PM, Fred Cisin via cctalk wrote:

Next step...
Apparently mu original Tandon floppy has bought the farm.
Does anyone know what the jumper setting are for a
TEAC FD-55GFR-149 for the TRS-80 4P?
I tried the usual (like for a DEC RX-33) but that didn't
fly.  Every sector fails verify after a format.  I am sure
it's a jumper thing.



On 5/5/22 13:34, Mike Loewen via cctalk wrote:
    The FD-55GFR is a 1.2MB drive, double-sided. The Model 4P used 
360K drives (possibly Teac FD-55A), single-sided as installed at the 
factory. Are you sure that's the model number that was in your 4P?


On Thu, 5 May 2022, Bill Gunshannon via cctalk wrote:

I know it wasn't.  The original was a Tandon 50.  But the TEAC
FD-55GFR (in various flavors) was used in a lot of systems and
at least one website said they were used in the 4P.  It is an
extremely configurable drive that I have used for numerous DEC
systems (even the infamous RX50!)  I have several of them and
it should work just fine if I can find the magic jumper combination.


The Teac FD-55GFR is a 96tpi drive.  It can replace a 55G (1.2M), or a 
55F (720K) depending on controller, but it still has a narrow head for 
doing 80 tracks.   It will have to be jumpered to run at 300RPM, not 360.


The FD-55B is double sided 48tpi ("360K"), and can be used in the 4P.
I don't know what, if anything needs to be done to use double sided in 
a 4P (software patches? jumpers on disk controller?), but people DID.

It's a worthwhile modification to do.
The 4D, and the later models of the 4P used Teac double sided drives 
(55B?)


On the other TRS80 models, the drive select jumpering was a little odd 
(although nor as odd as PC).  Like IBM, later, Radio Shack did not 
want to trust their people to be able to do the drive select jumpers.  
So, they jumpered DS0, DS1, DS2, and used side select as DS3 on model 
1!, then used a cable with the other drive selects removed.  So, with 
the stock cable, the first drive should work as DS0, but jumpers of 
DS1 and DS2 won't have any effect. 
https://www.tim-mann.org/trs80faq.html#[19]
Discusses the drive selects and Mentions that you can use 55GFR, but 
doesn't give the details that you need  (300/360 RPM, double stepping, 
etc.)



But, more importantly, is the fault ONLY when format/verify?
Does it still READ disks that you already have?


One more possibility to pay attention, (you probably already know 
this, so sorry if saying it offends you), ...
You need to use 300 Oerstedt ("360K") diskettes.  If you use 600 
Oersted (1.2M) disks, they will seem to work, and then immediately, or 
VERY soon, lose their content.

Re: The TRS-80 Journey Continues

[Fred Cisin via cctalk]

Next step...
Apparently mu original Tandon floppy has bought the farm.
Does anyone know what the jumper setting are for a
TEAC FD-55GFR-149 for the TRS-80 4P?
I tried the usual (like for a DEC RX-33) but that didn't
fly.  Every sector fails verify after a format.  I am sure
it's a jumper thing.



On 5/5/22 13:34, Mike Loewen via cctalk wrote:
    The FD-55GFR is a 1.2MB drive, double-sided. The Model 4P used 360K 
drives (possibly Teac FD-55A), single-sided as installed at the factory. 
Are you sure that's the model number that was in your 4P?


On Thu, 5 May 2022, Bill Gunshannon via cctalk wrote:

I know it wasn't.  The original was a Tandon 50.  But the TEAC
FD-55GFR (in various flavors) was used in a lot of systems and
at least one website said they were used in the 4P.  It is an
extremely configurable drive that I have used for numerous DEC
systems (even the infamous RX50!)  I have several of them and
it should work just fine if I can find the magic jumper combination.


The Teac FD-55GFR is a 96tpi drive.  It can replace a 55G (1.2M), or a 55F 
(720K) depending on controller, but it still has a narrow head for doing 
80 tracks.   It will have to be jumpered to run at 300RPM, not 360.


The FD-55B is double sided 48tpi ("360K"), and can be used in the 4P.
I don't know what, if anything needs to be done to use double sided in a 
4P (software patches? jumpers on disk controller?), but people DID.

It's a worthwhile modification to do.
The 4D, and the later models of the 4P used Teac double sided drives 
(55B?)


On the other TRS80 models, the drive select jumpering was a little odd 
(although nor as odd as PC).  Like IBM, later, Radio Shack did not want to 
trust their people to be able to do the drive select jumpers.  So, they 
jumpered DS0, DS1, DS2, and used side select as DS3 on model 1!, 
then used a cable with the other drive selects removed.  So, with 
the stock cable, the first drive should work as DS0, but jumpers of DS1 
and DS2 won't have any effect. 
https://www.tim-mann.org/trs80faq.html#[19]
Discusses the drive selects and Mentions that you can use 55GFR, but 
doesn't give the details that you need  (300/360 RPM, double stepping, 
etc.)



But, more importantly, is the fault ONLY when format/verify?
Does it still READ disks that you already have?


One more possibility to pay attention, (you probably already know this, so 
sorry if saying it offends you), ...
You need to use 300 Oerstedt ("360K") diskettes.  If you use 600 Oersted 
(1.2M) disks, they will seem to work, and then immediately, or VERY 
soon, lose their content.

Re: The TRS-80 Journey Continues

[Bill Gunshannon via cctalk]

On 5/5/22 13:34, Mike Loewen via cctalk wrote:

On Thu, 5 May 2022, Bill Gunshannon via cctalk wrote:


Next step...

Apparently mu original Tandon floppy has bought the farm.
Does anyone know what the jumper setting are for a
TEAC FD-55GFR-149 for the TRS-80 4P?

I tried the usual (like for a DEC RX-33) but that didn't
fly.  Every sector fails verify after a format.  I am sure
it's a jumper thing.


    The FD-55GFR is a 1.2MB drive, double-sided. The Model 4P used 360K 
drives (possibly Teac FD-55A), single-sided as installed at the factory. 
Are you sure that's the model number that was in your 4P?


I know it wasn't.  The original was a Tandon 50.  But the TEAC
FD-55GFR (in various flavors) was used in a lot of systems and
at least one website said they were used in the 4P.  It is an
extremely configurable drive that I have used for numerous DEC
systems (even the infamous RX50!)  I have several of them and
it should work just fine if I can find the magic jumper combination.

bill

Re: Different font for second 1 on commodore 1571 drives (and others)

[John Robertson via cctalk]

On 2022/05/05 10:26 a.m., Toby Thain via cctalk wrote:

On 2022-05-05 1:03 p.m., John Herron via cctalk wrote:
Someone at work pointed this out and I've never really thought about 
it. Is
anyone here aware of the decision or reason to use a different 1 
character

for the last 1 vs the first 1?


Got a picture?


They may have run out of that original font if they were setting the 
type with something like Lettraset in the day.


I restore and sell the first coin operated video game - Nutting's 
Computer Space - and they mixed all sorts of fonts on the control panel. 
It was a pain to reproduce it!


John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

Re: The TRS-80 Journey Continues

[Mike Loewen via cctalk]

On Thu, 5 May 2022, Bill Gunshannon via cctalk wrote:


Next step...

Apparently mu original Tandon floppy has bought the farm.
Does anyone know what the jumper setting are for a
TEAC FD-55GFR-149 for the TRS-80 4P?

I tried the usual (like for a DEC RX-33) but that didn't
fly.  Every sector fails verify after a format.  I am sure
it's a jumper thing.


   The FD-55GFR is a 1.2MB drive, double-sided. The Model 4P used 360K drives 
(possibly Teac FD-55A), single-sided as installed at the factory. Are you sure 
that's the model number that was in your 4P?



Mike Loewen mloe...@cpumagic.scol.pa.us
Old Technology  http://q7.neurotica.com/Oldtech/

Re: Different font for second 1 on commodore 1571 drives (and others)

[Toby Thain via cctalk]

On 2022-05-05 1:03 p.m., John Herron via cctalk wrote:

Someone at work pointed this out and I've never really thought about it. Is
anyone here aware of the decision or reason to use a different 1 character
for the last 1 vs the first 1?


Got a picture?

Different font for second 1 on commodore 1571 drives (and others)

[John Herron via cctalk]

Someone at work pointed this out and I've never really thought about it. Is
anyone here aware of the decision or reason to use a different 1 character
for the last 1 vs the first 1?

Re: The TRS-80 Journey Continues

[Bill Gunshannon via cctalk]

Next step...

Apparently mu original Tandon floppy has bought the farm.
Does anyone know what the jumper setting are for a
TEAC FD-55GFR-149 for the TRS-80 4P?

I tried the usual (like for a DEC RX-33) but that didn't
fly.  Every sector fails verify after a format.  I am sure
it's a jumper thing.

bill

Re: IBM 3725 MOSS cpu

[Bill Degnan via cctalk]

Dave McGuire would know this.  I can look it up if no one else knows
off the top of their head...
Bil

On Thu, May 5, 2022 at 12:10 PM IBM System/3 via cctalk
 wrote:
>
> Hi,
>
> Has anyone any information of the type CPU IBM used for the MOSS
> function in the IBM 3720/3725 ?
>
> Thanks !
>
> Henk
>

IBM 3725 MOSS cpu

[IBM System/3 via cctalk]

Hi,

Has anyone any information of the type CPU IBM used for the MOSS 
function in the IBM 3720/3725 ?


Thanks !

Henk

Re: DEC H7822 power supply

[Maciej W. Rozycki via cctalk]

Hi Peter,

> I still have the leaky electrolytics I removed from the POWER-ONE PSU in my
> Cisco IGS a while back.  I stored them with their leads up and goo seems to
> be still oozing out of some of them despite their inactivity and orientation.
> These ones are marked Nichicon PL(M) 4700uF/63V, 2200uF/16V and 330uF/35V and
> also have markings like H8950, H9018 and H8946 - maybe these are date codes?

 Right, my notes indicate Nichicon PL parts might be problematic too, e.g. 
one at 4700uF/10V on 5V output of the H7826 PSU.

> I also removed the smaller ones like 47uF/35V PF(M) H8952 for example but it
> is less clear to me whether these were leaking too or just got leaked on by
> the others.  There were only a few of them so I decided they were better out
> than in.  They all have similar coloured brown sleeves like the faulty ones
> in the DEC power supplies too.

 I can confirm now Nichicon PF 47uF/35V parts to be the source of an issue 
with my Bel Power.  All four leaked.  Thankfully I was able to fully 
revive that PSU (now in 24/7 operation).

> There are also the leaky 10uF/35V axial electrolytics in my LK201 keyboard.
> Those are in orange sleeves and marked "ESZ", whatever that is.  They have
> date codes like 8612.  I thought this might be a widespread problem but
> so far I have only found it in one keyboard.

 These are likely standard type parts.  I've yet to come across a low 
impedance axial capacitor type.  I may have missed something of course.

> Looks like I need to go back and recheck everything I thought wasn't leaking
> last time I checked :-(
> 
> Thing is, to check them, they have to come out of the case and that involves
> at least some change in orientation, except for contortionists...

 I doubt a temporary reorientation of parts you want to replace anyway is 
going to cause any trouble in that short amount of time.

> > Heat dissipated by the cap itself under high ripple current never helps 
> > and will surely speed up cap deterioration.  After all its service life 
> > halvens with each 10°C temperature rise even with non-faulty parts.
> >
> 
> When I was shopping for replacements, I was a bit alarmed to find that
> the maximum specified "endurance" (whatever that is) I could find was
> 5000 hours.  This isn't much more than a long life incandescent light bulb.

 Mind that it's at 105°C.  If you keep such caps operating at 65°C (which 
is still rather hot), then endurance raises to 8h (~9 years continuous 
use).

 Anyway try to chase replacements specified for at least 1h at 105°C.
Nichicon HE/UHE and Panasonic FR seem suitable replacements for Chemi-con 
SXF, Nichicon PL, surpassing old parts in terms of ESR/impedance/ripple 
and dimension-wise.

> All the leaking ones in DEC H7821 and H7822 PSUs I have come across so far
> are 1800uF/25V Chemicon with brown sleeves.  I think mine are all SXF
> but I am not 100% sure of that.  There are lots of other electrolytic
> capacitors in these power supplies but I've only looked closely at the
> larger ones.  All of the reservoir capacitors attached to the mains bridge
> rectifiers that I have seen look fine.  Maybe I need to go back and check
> the smaller ones though :-(

 I don't have any H7822 PSU.  Your experience with the H7821 is the same 
as mine though (and I still need to figure out what's wrong with one which 
still doesn't drive its power-good line active after recapping).  I used 
Nichicon HE P/N UHE1E182MHD as the replacement for those.  There does 
appear to be COVID-related shortage of this part (600 expected at Mouser 
15/03/2023, ugh!), which used to be readily available in large quantities 
several years ago.  However Panasonic FR P/N EEUFR1E182 is available in a 
small quantity (and is better).

> I think I came across some LXF ones that seemed to be ok, I can't remember
> where though.  I probably need to go find these and check them again :-(

 I came across LXF parts in one H7826 only and they were clean, but I 
chose to replace them as a precaution anyway as I've got stuck with trying 
to repair a couple of broken H7826 PSUs already still not working after 
cleaning the mess and replacing broken caps (mind that I'm a software 
engineer with enough hassle to sort out on the software side already).

> Here's a thought.  Apart from the keyboard, all the ones I have seen that
> are leaking are filtering the outputs of switch mode power supplies.  I
> wonder does the higher frequency of the ripple they are dealing with have
> a bearing on this?

 I've seen leaks from SXF parts on the primary side too with the H7826, so 
it is not that they only fail on the secondary side.  Also it is lower 
frequency ripple that's more problematic, see frequency correction factors 
for ripple current in datasheets, because impedance is higher at lower 
frequencies.  That's an inherent property of capacitance.

> I replaced the five leaking capacitors on the upper board in my H7822,
> disconnected the input to the lower