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Next Challenge: Hyperion that won't display text

falter

falter

Veteran Member
Joined
Jan 22, 2011
Messages
6,764
Location
Vancouver, BC
I feel like I'm ready to dive into this. To refresh: the Hyperion I have works perfectly in most aspects. It boots from boot disk, is responsive to keypresses, etc. I can put in a bootable Kings Quest disk and everything works great - internal and external monitor are nice and sharp. *But*

When in text mode- nothing. Bright orange screen. No text at all.

Doing lots of research, it seems this is a common issue that befalls lots of Hyperions. I suspect most of the ones I've read about have the same issue.

Here is the block diagram for the display board (thanks snuci for posting this): hyperion-display-block-diagram.jpg

So if I'm reading that right, low/hi res graphics are almost a separate thing from text. Since we know low/hi res graphics work, we can assume things like the CRT itself, sync, memory, etc all work.

So I feel like the issue is in the char gen somewhere. Here's the schematic for that: https://drive.google.com/file/d/1G1aIoWH5xjpE9w7gAoH8IO0uSKo3q5rL/view?usp=sharing

I'm thinking I should start with the obvious - check power first. Then maybe poke around the super and subscript logic and kind of work from there? I just want to make sure I understand the flow of things and which direction to work from. I'm really hoping the chargen EPROM isn't dead... don't know of any dumps of that... so I figure I'll start with the basics first.

Unfortunately Dynalogic soldered most chips in so this isn't going to be very much fun at all, esp. since the way it's held together with screws and standoffs is a bit of a bear.
 
Okay, so I did a bit of tracing with my logic probe. Here's what I found.

Starting at U6 (attribute decoder), I can see pulses/activity coming in on LAT0-LAT7. I can see pulses going out on FAT0-FAT7. I've followed FAT3 and FAT4 up to U1 (7474) and can see them pullsing the DATA pin, Pin 2. I can see a clock signal on pin 3 of U1 also. The SET pins on U1 are High, the RESET are low. There is nothing coming from Q1(? or 2?) pin 5. Pin 5's output goes to B1 of the binary adder (74LS283) at U2. I can see other 'data' or pulses on the other side of that adder (A1-A4), but nothing on the B side. If I understand correctly, a binary adder takes binary inputs from A and B and creates sums from them. So I'm wondering if something is going wrong with the 7474, and thus the binary adder isn't getting half of what it needs to perform?

Really wish the 7474 weren't soldered in.. would be an easy one to check.
 
Last edited:
Swapped out the 7474 ... definitely getting some pulse on pin 5 now. Nothing onscreen yet.. but I sort of jury rigged things by snipping off the old 7474 and attaching this one to the legs. Might not be secure on every pin. But I am definitely seeing a change, so that gives me inspiration to pull the boards apart and sort this.
 
Okay so my next suspect is this PAL10H8 at U6. If I'm reading the schematic right, pin 12 of U1 connects to 'FAT4', which is driven off pin 15 of U6 (a PAL10H8). If I've got this right, FAT4 should be driving the DATA pin 12 of U1 (7474). I've confirmed these are connected with a resistance check, but yeah, there's no activity there.

Now, I don't understand the PAL10H8 at all, and I might be reading the schematic too simplistically - but it seems like LAT4 goes into U6 at pin 5 and comes out as FAT4 on pin 15? Does that sound accurate to anyone in the know? I'm definitely seeing pulses at Pin 5, but no pulsing of any kind on Pin 15. So I'm wondering if I've got two bad chips here.. one 7474 at U1, which seems to be confirmed, and possibly this PAL10H8. I just don't know if it's as simple as I imagine with Pin 5 driving output to pin 15 or if something else has to happen and maybe some other IC elsewhere isn't driving something right with U6.
 
I'm starting to think I may have an issue with this SMC CRT8021-003 chip. I've been probing pin 1 (which on the schematic, says VID.. I think that's the video out signal).. my probe says it is high and cannot pick up any data or anything flowing through (no pulses). It goes to a 7474 at U49 and there are no pulses coming off the Q of that either. I'm going to try to find a replacement for test purposes but not much luck so far. If anyone out there has a working one please PM me, I'd like to buy.
 
Well, I've made *some* progress! I think.

As mentioned I have been zeroing in on the 8021-003 chip. I had noticed pin 1, the VIDEO pin seemed to be 'stuck' high and there were no pulses or 'audible' activity coming from it on my logic probe. As an experiment, I clipped pin 1 off to confirm that the 8021 had nothing to do with graphics. I was half right... doing that caused the graphics to lose their quality.. it was like shifting down from CGA to something worse. Could still make things out on my Kings Quest screen but it was darker and missing lines.

Anyway, I resoldered pin 1 back together again. I powered up, watching with my logic probe. All of a sudden, there's pulsing going on! Like really fast, data moving through! I look around front, and I've got a cursor!! It's not blinking, but it's there!

I let KQ2 boot up again and graphics were back to normal. I shut down, pulled the KQ2 disk out (there are two disks.. the boot disk and KQ2 itself). The cursor moves! The machine is clearly sending out prompts, although nothing is actually appearing!

So we've got cursor, but still no text. I'm going to try an actual Hyperion DOS disk just to confirm there isn't something about the generic PC DOS disk that isn't working with the Hyperion. But yeah.. I don't know what I did.. maybe the heat of the soldering iron shook something loose in the CRT controller?
 
Hi Falter,

I wish I could help but I have two Hyperions that do not show anything on the display. Thankfully I do have one working one. I am watching this thread with interest.
 
Yeah there are quite a few Hyperions out there with this affliction and they all present the same symptoms. Have you tried booting your no display ones like I have? What I did was make two disks.. one a DOS boot disk in Drive A with autoexec that calls SIERRA.EXE on the second disk in drive B, which is just a copy of the first disk of KQ3. That confirmed that graphics were working, just not text.

My gut feeling is this is going to turn out to be a weak-link IC... like the TED chips in the Commodore 264 machines... a chip that tends to fail after x number of years. Right now I am strongly suspecting the attributes controller (the 8021-003). I am just going over the circuit description and checking anticipated signals one more time before I pull the trigger on $100.

You or someone with a working Hyperion should probably dump the EPROM for the char generator, if it hasnt been done already. That's another suspect. But right now I'm zeroed in on the attributes controller.
 
I wonder... would it be possible to dump the EPROM from within dos? I am wondering if I can rig something up to do that automatically and write it to a txt file. Then I could see if mine is any good.
 
Okay so I have read the circuit description more and am starting to (I think) understand how different parts of the display board work and interact with each other. I can see for example the line that goes high or low based on whether the machine is in alphanumeric mode or graphics, and I can observe that line working as the machine loads Kings Quest. I can see data moving between the char gen EPROM and the attributes controller. The EPROM determines which characters to display, the attributes controller determines things like whether characters are underlined or blinking or superscript or subscript. I can see how super script and subscription attributes are triggered on or off in their own section.

One line that has caught my attention is CB3. According to the description, if CB3 is high, the character bits are passed unmodified past the attributes controller. If it is low, the attributes controller determines and applies the changes, like superscript or doublewidth and then modifies the bits to have those attributes.

What I am seeing right now is that CB3 is always low. So if I'm understanding right, this is forcing the attributes controller, which is a little iffy, to try to modify the text to be displayed. To what, I don't know. The super/subscript circuit is inactive, so it's not that. I don't think it's anything.. I think CB3 may simply be stuck low and maybe that's why it's producing nothing, because the attributes controller isn't getting any instruction on how to modify.

I think an experiment for tomorrow would be to figure out a way to either force CB3 high, or force one of the attributes (like underline) high to see if we get anything passing through the controller.

I've traced CB3 on the schematic back to (I think) my old arch nemesis... the 74LS273. I've tangled with these in several old video circuits and they do seem to have a higher than average fail rate.

Anyway... I'm not sure how I'll force CB3 or one of the attributes high.. but I'll figure something out.
 
I decided to put this on the bench and get it apart to check things. The first thing I wanted to do was make sure the Character generator ROM was good. I desoldered it and did a dump. Here is what I've got. I'm wondering if anyone with more experienced eyes can tell me if this looks like good data. I've not yet been able to find a dump of the char gen by anyone else so I don't have much to compare to. It's not all FFs, so I don't think the chip is completely dead.

https://drive.google.com/file/d/1lb6xMNb16myvISMnTzIKWP5G5g5W126J/view?usp=sharing
 
The first thing I wanted to do was make sure the Character generator ROM was good. I desoldered it and did a dump. Here is what I've got.
Click to expand...

It looks like you have captured the Characters. The Schematic shows you have either a Text or Graphics Selection. Then the U21 IC has Signals
SL0 - RS0 Pin 16
SL1 - RS1 Pin 15
SL2 - RS2 Pin 13
SL3 - RS3 Pin 14

Which give you Rows 0 thru 0xF = 16 Rows of Data for each character. I selected a couple at random (marked with *) and they look sane.

Code: 
00000000000000000000000000000000
003C4281A58181A599423C0000000000
003C7EFFDBFFFFDBE77E3C0000000000
000066FFFFFF7E3C1800000000000000
0000081C3E7F3E1C0800000000000000
0000081C087F2A080800000000000000
0000081C3E7F2A080800000000000000
00000000183C3C180000000000000000
00FFFFFFE7C3C3E7FFFFFF0000000000
0000003C424242423C00000000000000
00FFFFC3BDBDBDBDC3FFFF0000000000
00070305087088888870000000000000
00384444443810103810000000000000
00101C1E121010103070600000000000
003028342A262262E6CE0C0000000000
0008491C226322221C49080000000000
00004060707870604000000000000000
000002060E1E0E060200000000000000
0010387C101010107C38100000000000
00666666666666006600000000000000
007E9494947414141400000000000000
00384440384444380444380000000000  *
0000000000007C7C7C00000000000000
00081C3E0808083E1C087F0000000000
00103854101010101000000000000000  *
00101010101054381000000000000000
00000004027F02040000000000000000
00000010207F20100000000000000000
000000004040407E0000000000000000
0000002466FF66240000000000000000
00000000081C3E7F0000000000000000
000000007F3E1C080000000000000000
00000000000000000000000000000000
00181818181800181800000000000000
006C6C6C6C0000000000000000000000
0014147F147F14140000000000000000
0000183E403C027C1800000000000000
000062660C1830664600000000000000
00001824183A44443A00000000000000
00000C18300000000000000000000000
00000408101010080400000000000000
00002010080808102000000000000000
0000002A1C3E1C2A0000000000000000
00000008083E08080000000000000000
00000000000000181830000000000000
00000000003E00000000000000000000
00000000000000181800000000000000
00000102040810204000000000000000
00003C42464A52623C00000000000000
00000818180808081C00000000000000
00003C42040810207E00000000000000
00003C42021C02423C00000000000000
00000C14247E04040400000000000000
00007E40407C02027C00000000000000
00003C42407C42423C00000000000000
00007E42040810101000000000000000
00003C42423C42423C00000000000000
00003C42423E02423C00000000000000
00000018180000181800000000000000
00000018180000181830000000000000
00000408102010080400000000000000
000000007E007E000000000000000000
00002010080408102000000000000000
00003844041810001000000000000000
00003C425E565C403C00000000000000
00001824427E42424200000000000000
00007C42427C42427C00000000000000
00003C42404040423C00000000000000
00007C42424242427C00000000000000
00007E40407C40407E00000000000000
00007E40407C40404000000000000000
00003C42404E42423E00000000000000
00004242427E42424200000000000000
00003810101010103800000000000000
00000E04040444443800000000000000
00006224283028246200000000000000
00006020202020227E00000000000000
000042665A4242424200000000000000
00004262725A4E464200000000000000
00003C42424242423C00000000000000
00007C42427C40404000000000000000
00003C424242424A3C02000000000000
00007C22223C22226200000000000000
00003C42403C02423C00000000000000
00007C54101010103800000000000000
00004242424242423E00000000000000
00004242424242241800000000000000
0000424242425A664200000000000000
00004242241824424200000000000000
00004444281010101000000000000000
00007E04081020407E00000000000000
00001C10101010101C00000000000000
00004020100804020100000000000000
00003808080808083800000000000000
00000008142241000000000000000000
000000000000000000FF000000000000
000030180C0000000000000000000000
0000000038043C443E00000000000000
000060203C2222227C00000000000000
000000003C4040403C00000000000000
000006043C4444443E00000000000000
000000003C427E403E00000000000000
00001C22207820207000000000000000
000000003E44443C0478000000000000
000060203C2222226200000000000000
00001000301010103800000000000000
0000020002020242423C000000000000
00006020242830286400000000000000
00003010101010103800000000000000
00000000542A2A2A2A00000000000000
000000007C2222222200000000000000
000000003C4242423C00000000000000
000000007C22223C2070000000000000
000000003E44443C040E000000000000
000000006C3220202000000000000000
000000003E403C027C00000000000000
00002020207020201C00000000000000
00000000444444443E00000000000000
00000000424242241800000000000000
00000000414149552200000000000000
00000000442810284400000000000000
000000004242423E027C000000000000
000000007C0810207C00000000000000
00000C10103010100C00000000000000
00001010100010101000000000000000
00003008080C08083000000000000000
00000000314946000000000000000000
000008142241417F0000000000000000
00003C424040423C1808000000000000
00006600444444443E00000000000000
003060003C427E403E00000000000000
00386C0038043C443E00000000000000
0000660038043C443E00000000000000
00180C0038043C443E00000000000000
0018180038043C443E00000000000000
000000003C40403C1808000000000000
00386C003C427E403E00000000000000
000066003C427E403E00000000000000
00180C003C427E403E00000000000000
00006600301010103800000000000000
00386C00301010103800000000000000
00180C00301010103800000000000000
0066001824427E424200000000000000
0018001824427E424200000000000000
003060007E407C407E00000000000000
00000000370C3F4C3F00000000000000
00003E48487C48484E00000000000000
00386C003C4242423C00000000000000
000066003C4242423C00000000000000
00180C003C4242423C00000000000000
00386C00444444443E00000000000000
00180C00444444443E00000000000000
000066004242423E027C000000000000
0066003C424242423C00000000000000
00660042424242423E00000000000000
0000083E4848483E0800000000000000
00001820207020627C00000000000000
00004428107C007C1010000000000000
0000704870444E444400000000000000
00000C12103810906000000000000000
0030600038043C443E00000000000000
00306000301010103800000000000000
003060003C4242423C00000000000000
00306000444444443E00000000000000
00324C007C2222222200000000000000
00324C00615149454300000000000000
003C023E423E007E0000000000000000
003C4242423C007E0000000000000000
00001000101804443800000000000000
000000003E2020202000000000000000
000000007C0404040400000000000000
00206024281622440E00000000000000
002060242A162A4E0200000000000000
00001818001818181800000000000000
00000000122448241200000000000000
00000000482412244800000000000000
00228822882288228822880000000000
0055AA55AA55AA55AA55AA0000000000
00BBEEBBEEBBEEBBEEBBEE0000000000
00101010101010101010100000000000
001010101010F0101010100000000000
00101010F010F0101010100000000000
002424242424E4242424240000000000
000000000000FC242424240000000000
00000000F010F0101010100000000000
00242424E404E4242424240000000000
00242424242424242424240000000000
00000000FC04E4242424240000000000
00242424E404FC000000000000000000
002424242424FC000000000000000000
00101010F010F0000000000000000000
000000000000F0101010100000000000
0010101010101F000000000000000000
001010101010FF000000000000000000
000000000000FF101010100000000000
0010101010101F101010100000000000
000000000000FF000000000000000000
001010101010FF101010100000000000
001010101F101F101010100000000000
00242424242427242424240000000000 *
0024242427203F000000000000000000
000000003F2027242424240000000000
00242424E700FF000000000000000000
00000000FF00E7242424240000000000
00242424272027242424240000000000
00000000FF00FF000000000000000000
00242424E700E7242424240000000000
00101010FF00FF000000000000000000
002424242424FF000000000000000000
00000000FF00FF101010100000000000
000000000000FF242424240000000000
00242424243F00000000000000000000
001010101F101F000000000000000000
000000001F101F101010100000000000
0000000000003F242424240000000000
002424242424FF242424240000000000
00101010FF10FF101010100000000000
001010101010F0000000000000000000
0000000000001F101010100000000000
00FFFFFFFFFFFFFFFFFFFF0000000000
000000000000FFFFFFFFFF0000000000
00F0F0F0F0F0F0F0F0F0F00000000000
000F0F0F0F0F0F0F0F0F0F0000000000
00FFFFFFFFFF00000000000000000000
000000324C48484C3200000000000000
00003C427C42427C4000000000000000
00007E42424040404000000000000000
0000007E242424242400000000000000
00007E22100810227E00000000000000
000000003F4444443800000000000000
0000004242427C404080000000000000
000000023C4808080800000000000000
00007E183C423C187E00000000000000
00003C42427E42423C00000000000000
0000003C424224246600000000000000
0000001C10083C423C00000000000000
000000365D49495D3600000000000000
0000023C464A52623C40000000000000
00001E20407E40201E00000000000000
0000003C424242424200000000000000
0000007E007E007E0000000000000000
000008083E0808003E00000000000000
00006018061860007E00000000000000
00000618601806007E00000000000000
00000000000709080808080000000000
00080808084830000000000000000000
00000018007E00180000000000000000
000000324C00324C0000000000000000
00003C42423C00000000000000000000
00000000183C18000000000000000000
00000000181800000000000000000000
000F0808080868281800000000000000
006C3222222200000000000000000000
00304810207800000000000000000000
000000003C3C3C3C3C00000000000000
00000000000000000000000000000000

 
  
  
  00 --------
  38 --XXX---
  44 -X---X--
  40 -X------
  38 --XXX---
  44 -X---X--
  44 -X---X--
  38 --XXX---
  04 -----X--
  44 -X---X--
  38 --XXX---
  00 --------
  00 --------
  00 --------
  00 --------
  00 --------
  
  
  00 --------
  10 ---X----
  38 --XXX---
  54 -X-X-X--
  10 ---X----
  10 ---X----
  10 ---X----
  10 ---X----
  10 ---X----
  00 --------
  00 --------
  00 --------
  00 --------
  00 --------
  00 --------
  00 --------

So, it appears you have the characters captured. (I might be off a row or two, as the characters might be displayed
a row lower than I have selected.)


Larry
 
Thanks Larry.

Ok so I think this is coming down to the attributes controller. It's a pity the only places that have them want a minimum order of $200. There are quite a few Hyperions out there with this problem and I did read a few cryptic messages in other forums about how Hyperions go bad like this. Maybe gotta find other owners and do a group order.

The hint for me is the cursor on mine, which came back after I temporarily cut the Video out leg on the controller. After I resoldered I had a proper signal there and a cursor. But it doesn't blink and from what I can see the attributes controller handles the blinking.
 
falter,
In looking at the Technical manual and Maintenance manuals, there seems to be several different video boards. At least there
are several schematics. Better double check yours with the Manuals and make 100% sure you are using one that matches
your Board.

PS. I've got all the Character Generator Characters in a file, but they don't look very well being stretched with the characters
I've used to display them. I'm still trying things.

Larry
 
I'm being gently poked by The Hackery/Disappearing Inc. that they have FIVE Hyperions and they are about to get ready to start parts swapping and repairing them. This might be a good time if you are still working on this to schmooze on in and see if you can get in on the action.
 
Man I miss so many posts! Just catching yours now NeXT.

I think I am honing in on the problem. As I mentioned in another post, I ended up finding a supplier for the 8021-003 chip I needed. I got 10 of them (minimum order). I was a bit suspicious of their provenance, as they did not match the vintage looking pics the supplier sent me. I installed a new one and got no change, so I thought.. damn, these must be fakes. However, checking my logic probe and scope, it appears they *are* working and doing something.

So I re-read the 8021-003 datasheet, and it says you can pretty much connect a monitor directly to the VID pin. So I thought, ok, what the heck. So I connected a composite monitor's video pin to the VID pin on the SMC, and check this out:

20190911_212241.jpg

Now, I couldn't get the screen to stabilize, it was producing two or three cursors and waving them all over the place (maybe because the chip is in circuit) But -- there's text there! The SMC chip *is* producing text. It's just not getting to the screen or composite out on the machine.

So I gotta think my problem is downstream. Something in between the SMC and the video output. There's a 7474, a 7408, a 74157 and so on. All chips i have spares for, so I'm going to just dig into this sucker and replace em until I figure out which it is.
 
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