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Heathkit H11A Gett'er Working Thread.

AK6DN

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Boy those DS8641 sure do get hot. Is that normal?

No, it is not. Typical Pd is on the order of 150-250mW. They should never get too hot to touch. Warm at best.

Check if you shorted +12V or -5V rails by accident to some net attached to an 8641.
 
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bladamson

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Roger that. I'll go back to that card here in a few and make sure that it is indeed the DS8641 and not something nearby. I was feeling it through the solder side of the board, so I may have been confuzzulated.

Moved on to testing the four 4kw Heathkit memory cards. Every single one of them locks up the qbone memory test, no matter what segment I strap them for. At least I have schematics for them, but I think it's peculiar that they all seem to misbehave in exactly the same way. There are what appear to be tantalums on there, but it doesn't look like the supply rail is shorted. These *are* the cards that are driving the bus with LS240s, though, so perhaps their out-of-specness is the issue. Worrisome, as these cards are what I used as a template for designing the 4mb board on previous pages. D:

One oddity is that if I install the MSV11-B and any one of the Heathkit memory boards at the same time (strapped for different segments of course), the QBone goes into a boot-reset loop, but it will boot ok with just one or the other installed. The supply voltage does sag to around 4.6v (I am powering the whole backplane with a 4-pin molex connector on an ATX power supply), so maybe my supply current is insufficient. The supply appears to have one single shared 5v output that is claimed to be rated at 20A though, so hmmmm. I shall have to keep a closer eye on it as I continue testing.

I think I will set the Heathkit memory boards aside for the moment and come back to them later. If everything goes to plan they'll be set aside and kept with the machine as interesting ephemera but not actually used anyway. But I'd still like to get everything fixed.

Next up is a MSC 4601 RAM board that I have found basically zero documentation for. It will be interesting to try to suss out what the dip switches do.....
 

wa2flq

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The supply voltage does sag to around 4.6v (I am powering the whole backplane with a 4-pin molex connector on an ATX power supply), so maybe my supply current is insufficient. The supply appears to have one single shared 5v output that is claimed to be rated at 20A though, so hmmmm. I shall have to keep a closer eye on it as I continue testing.

This is a bit low to enable reliable operation. The Healthkit H11 manual calls for +5V. TTL Gates run at 5V +- .25v.

The 5V power supply of the H11 was fused for 20A, so I think you have enough capacity for testing a few boards. You should track down the voltage at each connection from the ATX. A poor connection may lead to voltage drop.
 

bladamson

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Yeah, this old junk power supply is entirely insufficient for this. I spent some time doubling up some of the wires to try to increase the current it could source and the voltage still sags when I have more than one card plugged in. I'll have to see if I can scrounge something better. Although once I am sure that none if these cards will smoke something somewhere I suppose I can move back to the H-11 and continue testing with it.

Good news is, the 32kW memory card appears to be a-ok, and there were only 4 bad SRAMs between all 4 of the Heathkit cards.
 

bladamson

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Alllllllllright! I've got the power supply issues solved, an ODT console up on a serial port, 8kW RAM, and 11/73 CPU, that all seem to be working correctly.

But I am still trying to figure out how to get the qbone to load paper tape BASIC.

Back to the documentation! Ha.
 

bladamson

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I am so close to having something I can do something with. I've got PDP-11 BASIC loading off a paper tape image and I can run it, but it spams a stream of READY at me endlessly. What do y'all suppose I am doing wrong here?

 

DDS

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Having a "new" machine with no (working) storage device and/or no way to load software has been faced by a lot of people and solved in a lot of ways. IMHO you should check out TU58FS.


All that's required is a second serial link to allow the PDP11 to hook up with the emulated TU58 "tape device." In the case of TU58FS, the software allows the PDP11 and the host computer to share a file system. You put files on the host system's disk and the PDP11 sees the files as being on the TU58's tape. If you have fast enough serial ports you'll have what looks like a TU58 that runs as fast as a disk. You can then run RT11 or XXDP and use their tools to support testing and bringing up the rest of your system.

Pretty slick!
 

Teletech

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Having a "new" machine with no (working) storage device and/or no way to load software has been faced by a lot of people and solved in a lot of ways. IMHO you should check out TU58FS.


All that's required is a second serial link to allow the PDP11 to hook up with the emulated TU58 "tape device." In the case of TU58FS, the software allows the PDP11 and the host computer to share a file system. You put files on the host system's disk and the PDP11 sees the files as being on the TU58's tape. If you have fast enough serial ports you'll have what looks like a TU58 that runs as fast as a disk. You can then run RT11 or XXDP and use their tools to support testing and bringing up the rest of your system.

Pretty slick!
Don't forget VTserver. A great (if slow) way to transfer a file system onto real iron through the console port.
 

wa2flq

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I am so close to having something I can do something with. I've got PDP-11 BASIC loading off a paper tape image and I can run it, but it spams a stream of READY at me endlessly. What do y'all suppose I am doing wrong here?


I've not used paper tape or this program.

I would try to halt and see what the code is around this point. Are interupts enabled for the console input or output? Does toggling the LTC on or off change anything?
 

daver2

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First of all, I would use SIMH to make sure that the paper tape image works and you understand how it works.

Second, I would look at what interrupts are being generated by the various cards - to make sure they are compatible with BASIC.

Have you tried to run the various paper tape diagnostics on your PDP-11 to make sure the CPU and memory is actually working?

Dave
 

bladamson

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I haven't tested the CPU, but I have tested all the RAM with the qbone.

I need to make some actual front-panel switches for my card testing backplane. For the moment I've been simulating them with the qbone, but that isn't terribly handy. Although what I have in there at the moment doesn't seem to be smoking the power supply or anything, so I guess it would be safe to try the same setup inside the H11 itself (although it isn't nearly as small and handy on the bench as this test rig).

The LTC signal doesn't seem to make any difference.

Although I wouldn't think paper tape BASIC would try to use the MMU (constraining it within the lower 64k), I thought that perhaps there was something peculiar going on with running a 22bit CPU in an 18 bit backplane with 16 bit RAM. So I pulled the 11/73 CPU and put in the 11/02 that the H11 came with, but it produces the same behavior.

The zkma memory test paper tape appears to be working as it should. But I need to find some documentation on it. I haven't let it run to completion yet.

If I remove all the physical memory and emulate 32kW with the qbone, I can boot RT11 through both floppy and hard disk emulation via the qbone, and everything appears to work. It hangs at boot when I have the physical RAM installed, though. This is with 12kW of the Heathkit RAM, or the 32kW MSC card. I think there is something wrong with the MSC card though. It tests ok with the qbone memory test, but the 11/73 fails with the "can't read location 0" LED on when it is installed.

12kW is supposed to be enough to boot RT11v3 (or so I've read). It starts to boot, then hangs before it prints the version number. The later releases of RT11 just hang before they print anything at all. I shall have to test the memory more aggressively.

So my conclusions thus far are:
1. Paper Tape BASIC has some kind of issue. Since I slept on it I seem to recall reading something somewhere about someone having trouble with it until they modified something on their serial card or something, but I can't remember the details and I can't find it now.
2. Something hinky is going on with my RAM cards. Maybe they are too far from the CPU.

My 22 bit memory arrived today, along with a grant card (so I can get all the RAM close to the CPU and put the qbone further down the chain). So I am going to switch back to the 11/73, install the 22 bit RAM, and try some of this stuff again. I shall have to wire wrap the backplane to 22 bits I guess.

Slow progress, but I guess progress is progress.

.

Edit:

Hmm, so in the backplane, my card chain is as follows: CPU -> Serial Card -> QBone (quad height with grant jumpers closed) -> BS0 4kW RAM -> BS1 4kW RAM -> BS2 4kW RAM.

Maybe the QBone needs to be on the other side of the RAM? The RAM doesn't watch any of the DMA lines though iirc, so it shouldn't matter..... Hmmm. For that matter I could probably put the RAM to the left of the CPU and not have to use a grant card to fit the qbone in...... Hmmmmmm.

Well anyway, I'll fool with it more later.
 
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AK6DN

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Is this the PDP-11 paper tape basic you are trying to run?
Code:
basic[507] pdp11 DEC-11-AJPB-PB.ini

PDP-11 simulator V4.0-0 Current        git commit id: 5a7a4c77
CPU     11/73, NOCIS, autoconfiguration enabled, idle disabled
        256KB
Disabling XQ
load DEC-11-AJPB-PB.ptap
run 16104

PDP-11 BASIC, VERSION 007A
*O ?
DO YOU NEED THE EXTENDED FUNCTIONS?Y
HIGH-SPEED READER/PUNCH?N
SET UP THE EXTERNAL FUNCTION?N
MEMORY?
READY
100 FOR I = 1 TO 10
110 PRINT I,I*I,I*I*I
120 NEXT I
130 END
RUN
 1             1             1
 2             4             8
 3             9             27
 4             16            64
 5             25            125
 6             36            216
 7             49            343
 8             64            512
 9             81            729
 10            100           1000

STOP AT LINE  130
READY
 

bladamson

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Yep, that's the one.

md5sum:
5b128945ef2b8f3d0e0cd899805a5a68 DEC-11-AJPB-PB.ptap

Looks like it's working for you! Maybe I should try the DEC serial card. Maybe the Heathkit one is doing something peculiar...
 

AK6DN

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Same one I used. Here is my SIMH setup FYI.

Code:
basic[507]
basic[507] md5sum DEC-11-AJPB-PB.ptap
5b128945ef2b8f3d0e0cd899805a5a68 *DEC-11-AJPB-PB.ptap
basic[508]
basic[508] cat DEC-11-AJPB-PB.ini
echo load DEC-11-AJPB-PB.ptap
load DEC-11-AJPB-PB.ptap
send delay=10000
expect "*O " send "?\r" ; cont
expect "FUNCTIONS?" send "Y\r" ; cont
expect "PUNCH?" send "N\r" ; cont
expect "FUNCTION?" send "N\r" ; cont
expect "MEMORY?" send "\r" ; cont
expect "READY\r\n" send "100 FOR I = 1 TO 10\r110 PRINT I,I*I,I*I*I\r120 NEXT I\r130 END\rRUN\r" ; cont
echo run 16104
run 16104
basic[509]
 

bladamson

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Some steps forward, some steps back.

The bad:

My MSC 32kW card seems to have stopped working suddenly. Bus timeouts. :( But I shall rearrange some cards and retest I suppose, with various termination and refresh signals.... I'd tested it with the qbone as bus master (no cpu) the other day and it tested fine, but now it won't respond at all. D:

With 12kW of Heathkit SRAM installed, everything hangs trying to boot, even though all the ram on those cards tested good. Weird. I guess I need to retest them.

The good:

My 2mb cards arrived yesterday. With one of them installed, various OSen seem to boot as they should. Although I cannot use more than 128kW until I wire wrap the backplane to 22 bits.

On that topic:

Unless I am full of poo, according to the documentation BDAL18..21 on the 11/2 CPU expose some troubleshooting signals or somesuch on the backplane. So if I wrap the backplane for 22 bits, I fear that trying to test stuff with the 11/2 in there will cause trouble. This leads me to think that maybe I should just cut the traces on the 11/2 card that connect to the BDAL18.21 pads on the edge connector, and then it will work in a 22 bit backplane without causing hinkiness. Would this be sacreligious? I'd hate to be excommunicated before the project is done, but on the other hand I kind of have a feeling that nobody really cares about the low-end CPUs. I'm happy as long as the modifications are documented and that documentation and all the original hardware stays with the H11 and all goes on to the next guy as a unit someday when I get mauled by a bear or something.
 

Teletech

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Some steps forward, some steps back.

The bad:

My MSC 32kW card seems to have stopped working suddenly. Bus timeouts. :( But I shall rearrange some cards and retest I suppose, with various termination and refresh signals.... I'd tested it with the qbone as bus master (no cpu) the other day and it tested fine, but now it won't respond at all. D:

With 12kW of Heathkit SRAM installed, everything hangs trying to boot, even though all the ram on those cards tested good. Weird. I guess I need to retest them.

The good:

My 2mb cards arrived yesterday. With one of them installed, various OSen seem to boot as they should. Although I cannot use more than 128kW until I wire wrap the backplane to 22 bits.

On that topic:

Unless I am full of poo, according to the documentation BDAL18..21 on the 11/2 CPU expose some troubleshooting signals or somesuch on the backplane. So if I wrap the backplane for 22 bits, I fear that trying to test stuff with the 11/2 in there will cause trouble. This leads me to think that maybe I should just cut the traces on the 11/2 card that connect to the BDAL18.21 pads on the edge connector, and then it will work in a 22 bit backplane without causing hinkiness. Would this be sacreligious? I'd hate to be excommunicated before the project is done, but on the other hand I kind of have a feeling that nobody really cares about the low-end CPUs. I'm happy as long as the modifications are documented and that documentation and all the original hardware stays with the H11 and all goes on to the next guy as a unit someday when I get mauled by a bear or something.
I agree that there is a vast and somewhat sad level of disinterest in the low-spec LSI-11 CPUs and that nobody is likely to begrudge you a couple traces.
I advocate for two chassis, one for the low-spec and one for your hotrod.
I'm pretty fond of my time playing Infocom games on an 11/03 with a RX01, it made charming crunchy noises.
 

bladamson

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I'm pretty fond of my time playing Infocom games on an 11/03 with a RX01, it made charming crunchy noises.

Exactly this. I want to run 2.11BSD and RSX11M on the H11, and put something together pretty low spec with what's left to run RT-11 for text adventures and BASIC and such. I'm not sure what to do for an enclosure. I have a gutted-except-for-the-CRT TRS-80 Model 4 and an extra video board from a Model II that I think would work on that CRT. Might be interesting to try to drive it with a custom FabGL timing or something. But that's a bridge to fall off of when I come to it.

Unfortunately I don't have any qbus floppy controller (although I do have a nice spare 8" drive in a very broken Tektronix 11/23 clone). There was a Zenith-branded dual 8" unit with controller that I could have gotten with the H11, but it was more expensive than it should have been and it's getting pretty hard to find reliable 8" media. But if I could scare up some sort of fairly flexible Shugart controller and some nice chunky full-height DS/DD 5.25 drives, I have more than enough well-preserved media for something like that. Maybe an H77 drive enclosure if I could find one.

I recall a 1.2Mb 5.25 bring a popular swap for an 8" in the big Tandies, but it's getting pretty hard to find good 1.2mb 5.25 media these days too.......

I guess I'm going off on a tangent, but I can't seem to get used to the silence of the floppulators. I have a clicker on the FloppyEmu on my Apple II, but it's not the same (it just snaps a relay one way or the other depending on whether or not one of the stepper lines is activated). It would be a really dumb project, but sometimes I think about sampling actual floppy and hard drive sounds and trying to make some kind of contraption with an atmega32 or something that would sniff on the disk drive interface and play the appropriate proper sounds over a carefully placed hidden speaker, heh.
 

Teletech

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Exactly this. I want to run 2.11BSD and RSX11M on the H11, and put something together pretty low spec with what's left to run RT-11 for text adventures and BASIC and such. I'm not sure what to do for an enclosure. I have a gutted-except-for-the-CRT TRS-80 Model 4 and an extra video board from a Model II that I think would work on that CRT. Might be interesting to try to drive it with a custom FabGL timing or something. But that's a bridge to fall off of when I come to it.

Unfortunately I don't have any qbus floppy controller (although I do have a nice spare 8" drive in a very broken Tektronix 11/23 clone). There was a Zenith-branded dual 8" unit with controller that I could have gotten with the H11, but it was more expensive than it should have been and it's getting pretty hard to find reliable 8" media. But if I could scare up some sort of fairly flexible Shugart controller and some nice chunky full-height DS/DD 5.25 drives, I have more than enough well-preserved media for something like that. Maybe an H77 drive enclosure if I could find one.

I recall a 1.2Mb 5.25 bring a popular swap for an 8" in the big Tandies, but it's getting pretty hard to find good 1.2mb 5.25 media these days too.......

I guess I'm going off on a tangent, but I can't seem to get used to the silence of the floppulators. I have a clicker on the FloppyEmu on my Apple II, but it's not the same (it just snaps a relay one way or the other depending on whether or not one of the stepper lines is activated). It would be a really dumb project, but sometimes I think about sampling actual floppy and hard drive sounds and trying to make some kind of contraption with an atmega32 or something that would sniff on the disk drive interface and play the appropriate proper sounds over a carefully placed hidden speaker, heh.
For the low-spec system I'm fond of the smaller q-bus chassis, the one the 11/03 tended to come in, the little one DSD made, or in the extreme the 4-dual-ht box dec made or the one tucked into a VT-1xx chassis.
I know the RX0x drives are dumb, but the clunk of the heads, click of the steppers, wish-wish of the 8" media, and slight squeak of the belt all contribute to the experience, so I'd have a hard time giving that all up. I see 8" media go wanting even at low prices around here, of course you'll need something else to format it with.
 
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