Has anyone set up a VBXE on a SM124 for 80 Col.

[Bee]

I'm wondering if a VBXE setup could drive a SM124 in a clean 80 column mode so I can use The Last Word?   Yes @flashjazzcat I'm considering building a A8 just for using the Last Word in 80C with my DotMatrix printer.

 

Anyone done this yet?

 

Thank you

[drac030]

From what I remember, SM124 is a b/w monitor with ~72 Hz vertical sync, and what I seem to vaguely remember, it also needs a digital video input signal. So it is a sort of digital, black and white VGA. I doubt if it can be driven with VBXE.

 

[TGB1718]

13 hours ago, drac030 said:

From what I remember, SM124 is a b/w monitor with ~72 Hz vertical sync, and what I seem to vaguely remember, it also needs a digital video input signal. So it is a sort of digital, black and white VGA. I doubt if it can be driven with VBXE.

 

I believe your right, I have an SM124 which unfortunately stopped working (not had time to find out why), so

I rewired a VGA plug to the end of one of my ST cables and used an old DELL VGA monitor which supported the

lower frequencies that modern monitors can't do, nice crisp black and white display in high res mode, so yes it's essentially VGA digital.

[Rybags]

My thought is it might be doable with a custom core.

Though the what ifs are things like - is the ~ 14 MHz speed of VBXE sufficient to produce a signal that the 124 would accept?

And what are the boundaries of what it would accept?  Could it tolerate a signal with less scanlines, slightly lower horizontal res and lower framerate?

 

But whatever the result, it's likely the generated graphics mode would be something unlike anything already on the A8.  Though of course if the target is just to produce something nice for WP and terminal work then that'd be fine.

[drac030]

The VGA cores required 28 MHz IIRC. Also the monitor itself may be pretty dumb and accept only its 72 Hz vertical sync / 36 kHz horizontal sync. I remember that even with Falcon030 video shifter, which is pretty flexible regarding the low level video settings, the only thing I could have done with SM124 was bumping the vertical resolution from 400 lines to something like 480 (or perhaps even 512, I do not remember). This was accomplished by lowering the lower border, the rest of video parameters were not tunable. But still, this perhaps was because it was just the legacy mode and they did not care to make it tunable (because admittedly who being sane uses Falcon030 with SM124?). So this still does not tell us much about the abilities of that monitor.

Edited March 8, 2020 by drac030

[Rybags]

Additionally I should have mentioned weren't there multiple revisions of that monitor?  Which could be another source of problems.

 

Given you probably would need the 28 MHz crystal it doesn't make sense really.  The purpose of the SM124 in the first place was to provide clear video at a time where 640x480 in colour was usually not the best quality or readability.   But since the 90s that problem was mostly eliminated (except in some cases refresh flicker).

So it's sort of redundant.

[Bee]

ok - I have this in my unpowered for over 30 years pile -

 

https://www.cnet.com/products/samsung-syncmaster-1100p-crt-monitor-21-series/

 

would it work with the vbxe?

 

Sorry but the VBXE is a black box to me.

 

Thank you

[Rybags]

Possibly not.  Once into the EGA/VGA era the horizontal refresh rate was generally 30 KHz or more.

VBXE is more along the lines of Amiga/ST/CGA type signals, virtually the same as TV.  16 KHz horizontal refresh and around 50 or 60 Hz framerate.

Non interlaced BUT - not a 400/480 line display but a 262/312 total line display.

 

What can work with VBXE are the arcade scandoublers which can be had around $25-$40 and will generate a modern day VGA type output from a 16 KHz RGB input.

[Bee]

OK - I'm going to punt and buy a referub'd SC1224 for the BVXE on a 130XE.

 

Thank you all

[Rybags]

I'll take a punt and guess that no workie with stock or VGA core.

 

But it would be interesting if someone could deduce what variance of frequencies it'll operate under.

[Cyprian]

On 3/8/2020 at 7:37 PM, drac030 said:

The VGA cores required 28 MHz IIRC. Also the monitor itself may be pretty dumb and accept only its 72 Hz vertical sync / 36 kHz horizontal sync. I remember that even with Falcon030 video shifter, which is pretty flexible regarding the low level video settings, the only thing I could have done with SM124 was bumping the vertical resolution from 400 lines to something like 480 (or perhaps even 512, I do not remember). This was accomplished by lowering the lower border, the rest of video parameters were not tunable. But still, this perhaps was because it was just the legacy mode and they did not care to make it tunable (because admittedly who being sane uses Falcon030 with SM124?). So this still does not tell us much about the abilities of that monitor.

I still have my SM124 with Falcon's video connector.

And yes, horizontal sync is crucial.

There is an instruction how to modify digital to analog path.

and someone has modified SM124 for his old Commodore CBM8296D

https://www.elektroda.pl/rtvforum/topic3441579.html#17112554

[Bee]

BTW - In The 1088XLD thread I have added a VBXE.  It was @stephan that originally got me to look at the VBXE, and gave me advice.  It was a few gentle nudges from @flashjazzcat To run The Last Word for my XMM801 as well as a few other helpful members here.  It was @MacRorie that suggested I add it to the 1088XLD build.  I will report back here when I have it up and running. 

 

Thank you - all 

[+Stephen]

37 minutes ago, Bee said:

BTW - In The 1088XLD thread I have added a VBXE.  It was @stephan that originally got me to look at the VBXE, and gave me advice.  It was a few gentle nudges from @flashjazzcat To run The Last Word for my XMM801 as well as a few other helpful members here.  It was @MacRorie that suggested I add it to the 1088XLD build.  I will report back here when I have it up and running. 

 

Thank you - all 

You will love it - I promise!