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SuperMac Spectrum/24 Project

Trash80toHP_Mini

NIGHT STALKER
So my ROM is earlier/less capable or later/more capable than the ROM @Aeroform is looking to source?
1003038-9002 COLORCARD SE/30 (c)1989 - mine
1003038-0001 COLORCARD SE/30 (c)1989 - his

As far as I'm concerned, my SuperMac Spec/8 SI is the cat's meow at 1152x870.
 

jmacz

Well-known member
So do I need a different oscillator to run 1024x768 at 60hz for different manufacturers? I have a Dell e153fpc lcd monitor (native 1024x768 at 60 and 75) and I can’t seem to get it to work right. The card is a series III and has the 30.24, 64, and 80 MHz oscillators, with one empty slot.
 

jmacz

Well-known member
  • So do I need a different oscillator to run 1024x768 at 60hz for different manufacturers? I have a Dell e153fpc lcd monitor (native 1024x768 at 60 and 75) and I can’t seem to get it to work right. The card is a series III and has the 30.24, 64, and 80 MHz oscillators, with one empty slot.

Hmm, I guess I was under the assumption that monitors that support resolutions at a particular vertical sync rate are standardized but I guess not?

DELL E153Fpc LCD (native resolution 1024x768)
  • Supermac Spectrum 24 III (1.1) - can't get anything to show up trying various options on my DB15/VGA 10switch adapter, for 640x480 or 1024x768 @ 60 or 75,
  • Radius PrecisionColor 8 - works for 640x480 which is the only resolution supported by the card that the monitor accepts.
  • Modern MacBook Air - works at 1024x768 at both 60 and 75.
  • Windows 10 Laptop - works at 1024x768 at both 60 and 75.
Samsung 512N LCD (native resolution 1024x768)
  • Supermac Spectrum 24 III (1.1) - drives at both 640x480 and 1024x768 (at both 60 and 75).
  • Radius PrecisionColor 8 - works at 640x480.
  • Modern MacBook Air - does not work.. detects the monitor but won't show an image at all at 1024x768 (60 or 75).
  • Modern MacBook Pro - does not work.. detects the monitor but won't show an image at all at 1024x768 (60 or 75).
  • Windows 10 Laptop - works at 1024x768 at both 60 and 75.
My Spectrum 24 III also doesn't show the custom monitor configuration options (running 1.1 ROM and 2.7.5 CDEV). I have 3 oscillators populated (30.24/64/80) and one slot empty.

Tried to run that Supermac Hypercard tool. I have HyperCard 2.2 on my IIci (System 7.1.1) but it looks like the stack was created using Hypercard 1.2.5 and so I can't edit the values as it's asking me to convert the stack first (which I'm not quite sure how to do since the menu is disabled when the stack is opened). I can't run the included HyperCard 1.2.5 as for whatever reason, that version of HyperCard seems to always crash my Macs, both my Quadra 700 (System 7.5.5) and IIci (System 7.1.1).
 
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MacOSMonkey

Well-known member
With the Spectrum/24 Series III, the problem may be that you are using the board in a non-cleared slot. Make sure you clear the slot PRAM before trying the board so that it will go into Round Robin by default (cycling configuration choice where you hit the space bar to set the config) at startup. Boot the machine with nothing in the slot, then insert the board, or zap PRAM on the Mac. Or, as I recall, you can also hold down the option key at power-on to initiate Round Robin.

Another problem may be the response time of the monitor, which may be slower than the time allowed for each sync config in Round Robin. You can try configuring the board at whatever mode you want on the other monitor, then plug in the Dell FP and see if it can sync up. The Dell monitor may be a little bit pokey on sync detect, depending on the output timing. (?)

If neither of those things helps, then you may not have the right sync output via the DB15->VGA adapter. The board obviously works, since it is working in your other config. Or, maybe the timing is out of spec for the Dell for some reason. You would need to look at the output signal on a scope.

The SuperMac stack probably isn't going to help you with this one -- also it predates the Spec/24 III.
 

jmacz

Well-known member
With the Spectrum/24 Series III, the problem may be that you are using the board in a non-cleared slot. Make sure you clear the slot PRAM before trying the board so that it will go into Round Robin by default (cycling configuration choice where you hit the space bar to set the config) at startup. Boot the machine with nothing in the slot, then insert the board, or zap PRAM on the Mac. Or, as I recall, you can also hold down the option key at power-on to initiate Round Robin.

I zapped the entire PRAM, a few times, unfortunately did not help.

Yes, if the card is in a slot it was not in before, it does that round robing thing (same when you zap the PRAM). And yup, you're right, it also does it if you hold down the option key on power on. But I believe all this does is allow you to choose the monitor/frequency and is useful if you only have one monitor. If you are able to boot, I think you get the same effect by opening the SuperVideo control panel and choosing the monitor manually and choose "Install", and then rebooting? or am I wrong?

I was debugging with two monitors connected. One was connected to the onboard video on my IIci (Apple 13" RGB) and the second to the Spec/24 III (one of a second Apple 13" RGB I have, the DELL, or the Samsung). The onboard video is the main so I can boot and see what I'm doing. I was doing all my tests via going into the SuperVideo control panel and choosing various resolutions, colors, and frequencies. The Spec/24 III worked great with the Apple 13" RGB and the Samsung LCD (at 1024x768 at both 60Hz and 75Hz). But nothing worked on the DELL. I thought something might be wrong with the DELL so I connected it via a VGA->USB-C adapter to my MacBook Air, and the DELL worked fine there (sharp and worked at both 60Hz and 75Hz). So nothing is wrong with the DELL, it just doesn't work with my vintage Mac via the VGA->DB15 10pin adapter I have. The Samsung however woks fine on my vintage Mac via that same adapter, but when connected to my MacBook Air, it doesn't work (no video). Go figure.

So sounds like even though two panels are at the same resolution, same V/H frequencies, same nominal clock frequency, there are some differences that cause it not to work on certain systems?

Another problem may be the response time of the monitor, which may be slower than the time allowed for each sync config in Round Robin. You can try configuring the board at whatever mode you want on the other monitor, then plug in the Dell FP and see if it can sync up. The Dell monitor may be a little bit pokey on sync detect, depending on the output timing. (?)

If my statement above that picking the monitor/resolution/frequency via the SuperVideo control panel is the same as what you might select via the round robin picker on boot, then I'm guessing this isn't the issue.

If neither of those things helps, then you may not have the right sync output via the DB15->VGA adapter. The board obviously works, since it is working in your other config. Or, maybe the timing is out of spec for the Dell for some reason. You would need to look at the output signal on a scope.

Yeah, I guess I'll have to compare the two via a scope.

The SuperMac stack probably isn't going to help you with this one -- also it predates the Spec/24 III.

Ah, ok. Thanks.
 

Phipli

Well-known member
So sounds like even though two panels are at the same resolution, same V/H frequencies, same nominal clock frequency, there are some differences that cause it not to work on certain systems?
Sometimes it is the types of sync - not all monitors support Sync on Green.
 

MacOSMonkey

Well-known member
Yes, if the card is in a slot it was not in before, it does that round robin thing (same when you zap the PRAM). And yup, you're right, it also does it if you hold down the option key on power on. But I believe all this does is allow you to choose the monitor/frequency and is useful if you only have one monitor. If you are able to boot, I think you get the same effect by opening the SuperVideo control panel and choosing the monitor manually and choose "Install", and then rebooting? or am I wrong?

It's the same -- it just sets/replaces the active config/sRsrcs for the board. If you only have 1 monitor, then you probably need Round Robin, since cable sense was limited on that board -- I forget -- maybe Apple 13" and 19" 1024x768 75Hz used it...maybe also Apple 16" , but not 19" 1024x768 60Hz, which was a legacy config at that point. Cable sense became more prominent beginning with the original Spec/24 PDQ and later, especially in the 21" 1152x870 configs, since the goal was to have them work out-of-the-box. If you can get to and see the desktop, then you can use SuperVideo. Otherwise, you need to zap PRAM, use Round Robin, use a clean slot, etc., so that you can config at startup in the correct mode.

So sounds like even though two panels are at the same resolution, same V/H frequencies, same nominal clock frequency, there are some differences that cause it not to work on certain systems?

If you are trying to convert DB15 -> VGA and you are getting no video, you will probably need an adapter with dipswitches that lets you manipulate how sync is being transmitted. They are available, I think. That may get it working. You should also look up the tech specs for the Dell and see what it requires. (Regardless, it obviously works in your other configs, so whatever it expects, it is not getting and it is likely a sync issue.)
 

jmacz

Well-known member
Sometimes it is the types of sync - not all monitors support Sync on Green.

If you are trying to convert DB15 -> VGA and you are getting no video, you will probably need an adapter with dipswitches that lets you manipulate how sync is being transmitted. They are available, I think. That may get it working. You should also look up the tech specs for the Dell and see what it requires. (Regardless, it obviously works in your other configs, so whatever it expects, it is not getting and it is likely a sync issue.)

I've been using a DB15->VGA adapter with 10 dip switches. I've been keeping a notebook trying every combination. I think I exhausted it for the Spectrum III / DELL combination with no success.

I also tried with a Radius PrecisionColor 8 (not 8XJ) and it worked with the DELL at 640x480 using 1467 which is 13" 640x480 @ 66Hz Mode 5 (sync on green) albeit scaled up (native resolution on the DELL is 1024x768 from 60-75Hz).

So I redid the test with Spectrum III / DELL using the various Mode 5 (sync on green) dip switch settings but none would get me a working image using the Spectrum III. The card itself was set to 1024x768 @ 60Hz. I also tried with 1024x768 @ 75Hz. Neither worked with any of the Mode 5 dip switch settings.

For the Samsung 512N (with Spectrum III), it worked under multiple dip switch settings. It's currently using 1256 which is 19" Color (1024x768) on Mode 2 (Composite Sync).
 

MacOSMonkey

Well-known member
I've been using a DB15->VGA adapter with 10 dip switches. I've been keeping a notebook trying every combination. I think I exhausted it for the Spectrum III / DELL combination with no success.

I also tried with a Radius PrecisionColor 8 (not 8XJ) and it worked with the DELL at 640x480 using 1467 which is 13" 640x480 @ 66Hz Mode 5 (sync on green) albeit scaled up (native resolution on the DELL is 1024x768 from 60-75Hz).

So I redid the test with Spectrum III / DELL using the various Mode 5 (sync on green) dip switch settings but none would get me a working image using the Spectrum III. The card itself was set to 1024x768 @ 60Hz. I also tried with 1024x768 @ 75Hz. Neither worked with any of the Mode 5 dip switch settings.
Hmm...since you have a scope, compare the sync width and shape between the PC-8 and Spectrum/24 III. The rework cap on the Bt output that is bent over the top of the part on Spec/24 III (which I think is on green - but check the pins) is there to minimize vertical line shadowing (voltage ringing/overshoot). The cap doesn't completely eliminate the problem, but it fixes it beyond the threshold of general user awareness/detection. So, maybe the sync is out of spec vs. the Dell monitor requirements, or maybe the cap is affecting the waveform in a way that prevents it from syncing (it's going to round it off and, therefore, shorten the valid high period). The video signal is obviously present and functional based on the other monitor you have, so it must be some spec/voltage issue. Maybe the Dell FP is more sensitive to deviations and requires longer to sync up. The problem might also relate to other aspects of the video timing (blanking, etc.). As a quick test, you could try just removing the cap to see if that changes the behavior, but there will be increased vertical ringing in the video output visible as shadowing on high frequency color changes -- like the black and white borders of folders, etc.

Edit: (...and for that cap, there may be a better way to fix -- or prevent -- the problem. It was just the easiest manufacturing rework hack so that the board could ship. But, it would be a research project. For example, the problem may be lack of VRef stability, etc., or some other instantaneous power draw issue -- which is probably greatest when transitioning from black to white. So, if not specifically an output problem, maybe there is a front-side or local bulk capacitance solution that would work...but require more parts or be trickier to implement -- who knows? It could also just be a Brooktree issue that requires overshoot management. However, I think this issue was addressed more successfully in later boards -- whether Bt or ADV-based -- to improve general video quality.)
 
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jmacz

Well-known member
Wow, that's some detailed info! Thank you! :) Will add the above to my list of weekend todo projects. There's always a bit of frustration with these things not working, but at the same time, all of this tinkering, debugging, etc has actually been kinda fun. Like solving a puzzle.
 

Phipli

Well-known member
Hmm...since you have a scope, compare the sync width and shape between the PC-8 and Spectrum/24 III. The rework cap on the Bt output that is bent over the top of the part on Spec/24 III (which I think is on green - but check the pins) is there to minimize vertical line shadowing (voltage ringing/overshoot). The cap doesn't completely eliminate the problem, but it fixes it beyond the threshold of general user awareness/detection. So, maybe the sync is out of spec vs. the Dell monitor requirements, or maybe the cap is affecting the waveform in a way that prevents it from syncing (it's going to round it off and, therefore, shorten the valid high period). The video signal is obviously present and functional based on the other monitor you have, so it must be some spec/voltage issue. Maybe the Dell FP is more sensitive to deviations and requires longer to sync up. The problem might also relate to other aspects of the video timing (blanking, etc.). As a quick test, you could try just removing the cap to see if that changes the behavior, but there will be increased vertical ringing in the video output visible as shadowing on high frequency color changes -- like the black and white borders of folders, etc.

Edit: (...and for that cap, there may be a better way to fix -- or prevent -- the problem. It was just the easiest manufacturing rework hack so that the board could ship. But, it would be a research project. For example, the problem may be lack of VRef stability, etc., or some other instantaneous power draw issue -- which is probably greatest when transitioning from black to white. So, if not specifically an output problem, maybe there is a front-side or local bulk capacitance solution that would work...but require more parts or be trickier to implement -- who knows? It could also just be a Brooktree issue that requires overshoot management. However, I think this issue was addressed more successfully in later boards -- whether Bt or ADV-based -- to improve general video quality.)
Would a fast, non-inverting buffer help? This isn't crazy speeds is it, its not like pixel clock, its going to be once per line or once per full screen (I wasn't paying enough attention sorry).

Edit : So double figure μS speed range minimum if it was once per scanline. Which well within the speed of any buffer you're likely to use.
 

MacOSMonkey

Well-known member
Would a fast, non-inverting buffer help? This isn't crazy speeds is it, its not like pixel clock, its going to be once per line or once per full screen (I wasn't paying enough attention sorry).

Edit : So double figure μS speed range minimum if it was once per scanline. Which well within the speed of any buffer you're likely to use.

You have to identify the problem first...but it does feel like a timing issue. ;-)

@jmacz: yes - The retro stuff is fun. I wish I had more time or awesome cloning technology. One of my clones would definitely just want to mess around on retro Macs and program in pre-CFM, flat memory 68K. YASSS!! WRITE ALL THE LOCATIONS!! ^_^
 
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