Getting 1152x870 on a 650 with a non-Apple multiple sync monitor

[jessenator]

So, in reference to an earlier post, I'm wondering what options there are. Here's what I said in detail there:

https://68kmla.org/bb/index.php?threads/what-did-you-do-to-your-apple-mac-today.30590/post-432545

Long and short, the flat panel I have will output the desired resolution and refresh, and my slower 8-XJ card will output, but I'm looking for the faster, native graphics chipset to output to my Sony multi-sync display.

So far, I have a fixed-resolution NEC adapter (832x624), a ViewSonic DIP adapter (which strangely doesn't support 1152x870 on the 650...the piece of paper in the plastic shows only 'Centris 650' so it predates the Quadra proper), and just acquired one of the gray NEC """""multisync""""" adapters, which really just supports 3 resolutions, the highest being 1024x768 (in fact, on the side opposite the NEC logo, it shows those three resolutions—something carefully omitted from the eBay listing).

I'm wondering if there's another solution out there for 1152x870 short of finding a newer-than-what-I-have, late-stage DIP adapter like this one.

I also have, what is hand-labeled to be, a Pivot monitor cable,. 3-row DB-15 on one end, and 2-row DA-15 on the other. I don't know what voodoo is happening in the cable, but it won't work at all with the built-in video. Works fine with the PrecisionColor card I have, but radius plays with radius, I guess. Incidentally, it only supports 1150x870 while using the card...

Anyway, wondering if anyone's dealt with this scenario before.


Also, for those curious, here's the NEC adapter with its plastic sheath removed:

reminiscent of a surplus ammo can from eastern Europe just completely covered in solder. I think part of me was hoping there was something to tweak to get two-page mode...

 

[MacKilRoy]

I have NEC video adapters for Mac that have more than the 3 resolutions normally found on them.

Here are two that I have. One is not NEC and the other was advertised as an NEC adapter, looks styled like one, but lacks the NEC branding. I’m pretty sure I have other ones with high resolutions like these but they say NEC on them.

 

[Trash80toHP_Mini]

That yellow one is the bomb, but I've never flipped the switch from 1600x1200. For normal range TPD resolutions I use the "Liberty Adapters" you'll see that have a rotary dial with the Liberty Bell on it for setting resolutions, so easy to use and highly recommended.

This one works very well: https://www.ebay.com/itm/234334794032 DIP adapters are great. if you're not testing multiple resolutions.

I have a what I call the "Magic Cable" where all is done in a a 6" cable that's worked with every resolution I've ever thrown at it. I've never tried it at 1600x1200. I can't imagine we couldn't come up with a wiring diagram to recreate that one, there's only one active little thingum involved. It's so great to have its nice flexible cable turn at right angle to minimize wall to computer distance. Methinks it's a nightmare in terms of RFI as it looks a lot like unshielded four pair TelCo cable.

BTW, the Liberty Adapter looks much like your ammo can inside.

 

[jessenator]

One is not NEC and the other was advertised as an NEC adapter, looks styled like one, but lacks the NEC branding.

Thanks! I'll look into one of those.

I have a what I call the "Magic Cable"

What's odd is that my Pivot cable "just works" in my ppc machines and that flat panel, but that might just be the nature of ppc video ¯\_(ツ)_/¯

 

[Melkhior]

All the information you need about how the 'sense codes' work is there: https://github.com/sfiera/mactech/blob/master/displays.rst, including schematics to roll your own - which might be cheaper than buying a vintage one.
My Q650 displays up to 1152x870 when set to "Apple Multiple Scan 20 Display" (G=4, 10→7) with a home-made adapter based on those schematics; I do have the maximum VRam of 1 MiB in it.

 

[NJRoadfan]

Does the Mac DB-15 output +12v on pin 8 like the Apple IIgs does? Just wondering how "active" adapters that do sync conversions like my Belkin are getting power for the logic?

 

[Cory5412]

"Active"?

As far as I know, these are all just pin adapters. The DIP switches or rotary dials on the adapters that have them are "for" forcing specific sense pins on macs and older graphics cards that expect them. The 8*24, for example, is probably expecting sense pins which the multiple scan 20 provides if I remember correctly but, say, a generic PC monitor typically won't.

The NEC adapter as pictured here should just be a passive adapter from the Mac DA15 pinout to the "VGA" DB15 pinout.

So, that's the other thing is... on the Mac, there is no sync conversion. These adapters or the monitors on the far side tell the Mac what the monitor can do or the Mac guesses. Never in any of these adapters is, say, 67Hz converted to 60Hz. Most Mac graphics adapters don't even bother with things you'd see on SGI/Sun adapters like Sync on Green conversion to separate sync lines.

"Magic Cable"

That's probably just a normal da15 to db15 cable. Some of the late-stage MultiScans (1705 for example) included them.

Have you ever gotten it to work on a Mac or card that doesn't do multisync on its own, like the IIci/IIsi? (It may work, just, at the default 640x480@67 for most macs/cards pre-multisync, which really started coming in with the Quadras.)

 

[Trash80toHP_Mini]

"Active"?

Kinda: diode = curiously limited switching on yellow adapter?

 

[NJRoadfan]

The Belkin adapter I have does appear to do sync signal separation and it works on the IIgs (machine supports composite sync and SoG only). The chip requires a power source and the only pin that appears to provide anything usable is pin 8. The IIgs doesn't have sense pins, so the adapter can't be vampiring power from there.

https://www.belkin.com/support/dl/f3h1381revised.pdf

DIP switches 5 and 6 set external sync. For Mac IIci, IIsi, IIvi, IIvx, or any computer that uses "sync on green", these are to be turned OFF. For all other computers, they are to be turned ON.

DIP switch 7 is composite sync and it is rarely used. Try turning it on and observe if it improves results.

VGA is a H+V sync standard and just about every monitor requires it. Some select VGA monitors (including the OSSC) support Sync-on-Green (anything Sony) or composite sync on the H-sync pin 13, but they are far from common. Without a sync seperator, getting ANY video on a IIci,IIsi,IIvi,IIvx and the early Apple NuBus video cards would be impossible for these adapters.

Below is printed on the back of the adapter, not documented in the manual.

DIP 5,6 ON: H+V Sync
DIP 7 ON: Composite Sync
DIP 5,6,7 OFF: Sync-on-Green
DIP 8 ON: VGA (This appears to enable Type-6 sense multi-sync mode on the Mac)

Best I can figure is DIP 5 and 6 switch the VGA H and V sync pins between the DB-15 output and the output from the sync separator. DIP 7 likely switches the input of the sync separator between the DB-15 green video pin 5 and composite sync output on pin 3.

 

[Melkhior]

Without a sync seperator, getting ANY video on a IIci,IIsi,IIvi,IIvx and the early Apple NuBus video cards would be impossible for these adapters.

Huh? I have a IIci and it can display just fine on a Iiyama E2473HS (not very recent but still a full HD LCD) through my home-made trivial adapter (the one whose design I linked to in a previous post). Same adapter also works for a LCIII and a Quadra 650. The only sync signals wired are the separate ones (pins 12 and 15 mac-side).
It is possible Iiyama has sync-on-green capability, but the specifications only mention spearate sync. I guess a logic analyzer would tell the full story about what is really on pins 12 and 15.

 

[NJRoadfan]

I'd expect something from a high end brand like Iiyama to support sync-on-green. The specs also say it supports 24khz h-sync signals, which is unusual. Most monitors are limited to 31.5khz (VGA) or higher, although there are some that will scan down to 15khz as an undocumented feature.

 

[NJRoadfan]

OK, reading the IIci Developer Notes, the machine outputs H+V sync or composite sync depending on the mode. Portrait mode is H+V sync, while 13in RGB is composite sync. The latter is what is usable by VGA monitors, but that would require sync separation. I'm assuming the IIci always outputs sync-on-green as well.

 

[NJRoadfan]

Found this: https://www.applefritter.com/node/6301

Apparently there is a way to power the sync separator using the sync pins.