Today I’m happy to share a long-overdue new product announcement, as well as a firmware update for the BMOW Floppy Emu disk emulator.

The new product is an updated Macintosh ROM SIMM, the Mac ROM-inator II Carbon, which has replaced the ROM-inator II Atom. The Carbon has already been in the BMOW store for several months, but I never got around to formally announcing it until today. Like all versions of the ROM-inator II, the Carbon offers a great upgrade for the the Macintosh SE/30, IIx, IIcx, IIci, IIfx, and IIsi, offering a bootable ROM disk, 32-bit cleanliness, HD20 hard disk support, and more. The Carbon has twice as much memory (4 MB) as the previous ROM-inator model, which enables the storage of a substantially larger compressed ROM disk. The Carbon’s ROM disk contains a full version of System 7.1 along with a suite of recovery/diagnostic utilities that have proven useful. Compared to the Atom, the Carbon has a larger selection of utilities and games, and the System folder is more amply populated.

Version 250225A of the Floppy Emu firmware addresses a bug that affected some WOZ disk images for Apple II computers, causing them to fail to load correctly, and making it difficult or impossible to format WOZ images. I only became aware of this bug a few days ago, but determined that it’s been present since November 2022! I am scratching my head over how it could have been broken for so long without me or anyone else noticing. Probably we all chalked up any WOZ problems we encountered to other issues, and didn’t notice that disks that worked in 2021 and early 2022 firmware versions did not work under later firmware versions. If you use WOZ disk images frequently with your Floppy Emu and Apple II, you’ll definitely want to get this update. The Macintosh/Lisa version of the firmware was not affected and has not changed. Apologies for letting this issue go undetected for so long!

The Wombat ADB-USB input converter is now back in stock! Thanks for everybody’s patience during this manufacturing delay.

The Wombat is a bidirectional ADB-to-USB and USB-to-ADB converter for keyboards and mice.

• Connect modern USB keyboards and mice to a classic ADB-based Macintosh, Apple IIgs, or NeXT
• Connect legacy ADB input hardware to a USB-based computer running Windows, OSX, or Linux

No special software or drivers are needed – just plug it in and go. The Wombat is great for breathing new life into your vintage Apple hardware collection.

You’ll find the Wombat here in the BMOW Store. For more details, please see the product description page.

For those who’ve been waiting, the Floppy Emu Deluxe Bundle and the Frosted Ice Acrylic Case are back in stock at the BMOW Store. While you’re shopping, check out the new Mac VGA Sync-inator too!

Floppy Emu is a floppy and hard disk emulator for classic Apple II, Macintosh, and Lisa computers. It uses an SD memory card and custom hardware to mimic an Apple floppy disk and drive, or an Apple hard drive. The Emu behaves exactly like a real disk drive, requiring no special software or drivers. It’s perfect for booting your favorite games and software, or transferring files between vintage and modern machines. Just fill your SD card with disk images, plug in the Emu board, and you’ll be up and running in seconds.

Today I’m very excited to officially announce a new addition to the BMOW product lineup: the Mac Sync-inator VGA sync converter. I’ve been talking about this project for months, and it’s been available in small quantities while I gathered customer feedback, but now it’s finally ready for the bright lights and prime time. If you own a classic Macintosh or Apple IIgs computer, and have ever struggled to get it working with a standard VGA monitor, then the Mac Sync-inator is for you.

The Sync-inator is an adapter for connecting Apple video sources (DB-15) to VGA monitors (HD-15), with active sync processing circuitry that sets it apart from typical passive video adapters. There’s a built-in microcontroller that analyzes the incoming sync signals in real-time, automatically selects the best adapter settings, and can optionally reprocess the sync signals into a different format for better compatibility with some VGA monitors. You can even view a debug log of diagnostic and technical information about the video signal, as seen by the Sync-inator. For video format nerds as well as for people who want something that “just works” with minimum hassles, there’s a lot to be excited about here.

Sync-inator Benefits

• Three different sync processing modes, for wider compatibility than other VGA adapters
• Automatic sync mode selection, for easy setup
• Sync activity LEDs for quick troubleshooting feedback
• Serial port output of video signal diagnostic info
• Plus all the other capabilities of standard VGA adapters

 
What is this and why should I care?

In short, the Sync-inator makes it possible to use many types of VGA monitors that previously wouldn’t work with your classic Apple video source due to sync compatibility issues. It also removes much of the frustration that’s typically associated with using passive DIP switch VGA adapters, by using a microcontroller to automatically configure some of the adapter settings. It will do everything that common passive Mac-to-VGA adapters will do, plus more. If you’ve got a monitor that stubbornly refuses to work with your vintage Mac video card, give the Sync-inator a try.

Sync-inator is not a video scaler, and it doesn’t modify the video resolution or colors in the RGB video signal. Only the sync signals are affected.

 
What the heck is sync?

The video signal from your computer or video card contains synchronization information which helps your monitor detect the beginning of each new line and new frame. There are several different ways in which this sync information can be encoded. Some computers only support specific sync methods, and some VGA monitors can only handle specific sync methods. If your monitor can’t handle the sync signals from your computer or video card, then you’ll have a problem, even if the monitor supports the video resolution and frame rate.

In the world of classic Apple computers, the two most common sync methods are composite sync and separate sync. With composite sync, the horizontal and vertical sync information is combined into a single output signal. With separate sync, horizontal and vertical information is transmitted with two distinct sync signals. Some computers can only output composite sync, or can only output separate sync. Some computers output one or the other at different times, depending on which specific video resolution is active. Some computers output both composite sync and separate sync simultaneously.

The Sync-inator is able to convert a composite sync signal into separate horizontal/vertical sync signals, using several different methods. It’s also able to analyze the incoming sync signal and make an educated guess about which conversion method is best, although this choice can be overridden if you prefer a different method.

 
What’s wrong with my computer? Is it even working?

The Sync-inator also has two built-in LEDs for debugging and troubleshooting video problems. If your monitor remains dark and no image appears, the LEDs can provide information to determine if the problem is with the monitor, the computer, the choice of video resolution, or something else. One LED will light whenever a composite sync signal is present, and the other LED will light whenever a separate sync signal is present. If neither LED is lit, then your computer isn’t outputting any video, and you’ll need to troubleshoot the source. If one or more LEDs are lit, but the monitor doesn’t show any image, then you’re likely dealing with some kind of unsupported video mode and will need to troubleshoot the monitor itself.

 
Debug Log

The Mac Sync-inator has a serial port where debug logging information is provided. The debug log is an optional feature, and all the Sync-inator’s capabilities can be used without ever looking at the log. But advanced tech nerds may find the log info interesting. To view the log, you can attach a USB serial cable to the TXD and GND terminals at the edge of the Sync-inator PCB, and set your terminal software’s serial port speed to 57600 bps. The debug log lists the current sync processing mode, including the result of the automatic processing mode’s analysis, as well as the period and frequency of the detected sync signals and other technical information. Here’s an example showing an Apple “Toby” NuBus video card running at 640×480 @ 67 Hz resolution.

* BMOW VGA Mac Sync-inator, v 1.0
sync mode: choose automatically
detecting sync signals...
hsync no
vsync no
csync yes
csync horiz period 28.5 us, freq 35.0 kHz
csync vert period 15.0 ms, freq 66.3 Hz
auto-select: convert csync into hsync and vsync
csync: pulse width 9 20 871, period 142 285 1003

 
Get your Sync-inator Now

For details on the Sync-inator, usage instructions, or to make a purchase, please see the main Sync-inator page at the BMOW web site. I hope this new device will be as useful for you as it has been for me!

I’m beginning to see the light at the end of the tunnel for my Mac Sync-inator Mac to VGA adapter. The hardware is essentially final now, and all that remains are software tweaks, which are mostly related to the new composite sync splitter behavior. Along the way I’ve amassed a large test fleet of different monitors and an even larger number of Macintosh and Apple-compatible video sources, and testing all those combinations has been very slow.

 
Elevator Pitch

The Sync-inator is a small in-line dongle that aims to be a “pro version” of the Mac to VGA adapters you likely already have, and that takes some of the frustration out of the Mac-to-monitor setup dance, and enables some new combinations of video sources and monitors to work together that were previously incompatible.

The Sync-inator works by rerouting, modifying, or splitting the sync signals from the video source before they’re sent to the monitor. It’ll do everything that common Mac to VGA adapters (e.g. Belkin) will do, plus more. Sync-inator is not a video scaler, and the timing and resolution of the RGB video signals are not modified in any way, only the sync.

The Sync-inator’s “normal” features are:

• DIP switches to set the desired video resolution. Settings for common resolutions are printed on the back of the device.
• Configurable passive methods of sync pass-through, like a sync switch matrix.

The “pro” features of the Sync-inator over standard VGA adapters are:

• Micrcontroller-driven active splitting of a composite sync signal into separate hsync and vsync signals. This is essential for older video sources that only provide composite sync. Although some monitors can handle composite sync or sync on green directly, many can’t, and for those monitors a composite sync splitter is required. This is what motivated this project initially, trying to get my Mac IIci built-in video working on one such monitor.
• Auto-detecting and auto-configuration of the sync behavior, reducing the typical setup hassles experienced with other adapters. If it senses that hsync and vsync signals are already present, it’ll simply pass them through. If those signals aren’t present, then it’ll kick over to composite sync splitter mode.
• Sync-inator has two LEDs that will visually show whether the video source is outputting composite sync, separate h and vsync, both, or neither. This should further reduce setup hassles, by making it easy to distinguish between cases where there’s no picture due to sync/resolution compatibility problems versus cases where the video source isn’t outputting anything at all.
• Sync-inator has a serial port that will dump a bunch of diagnostic info about the video source and its characteristics and timing. That’s fun for video nerds, and maybe useful for something.

“Sync splitting” is a slightly misleading term, because it sounds like there are already two signals that simply need to be separated. In reality it’s more like “sync generation”, synthesizing two wholly new hsync and vsync signals using the csync signal as a reference. This is straightforward in theory, but in practice it’s proven challenging to get every timing detail 100 percent right. Along the way I’ve discovered that some monitors care about certain aspects of hsync and vsync that others don’t seem to: like whether they trigger from the hsync falling edge, rising edge, or both edges, their sensitivity to changes in hsync pulse width, and their tolerance for small amounts of jitter in sync signal edges.

 
Apple IIgs Testing

The Apple IIgs uses the same DB-15 port as early Macintosh computers for connecting RGB monitors, so I wondered whether the Sync-inator could also be made to work on the IIgs. The answer is mostly yes, although there are a few things to watch for. Although the IIgs uses the same pins as the Mac for RGB signals, grounds, and composite sync, some of the other pins are different. On the Mac, three pins are used as a Sense ID to set the desired video resolution, but the IIgs uses one of these same pins for a -5V power supply. It doesn’t need a Sense ID since it always outputs the same video resolution. Unfortunately this means one of the Sense ID DIP switch combinations will connect the IIgs -5V supply to GND. This isn’t fatal, but it prevents the IIgs from turning on, and it’s definitely not good. For IIgs use, the Sense ID switches can all be turned off.

Another challenge for the IIgs is the horizontal sync rate of 15.7 kHz, which is much lower than typical monitors will support. Even if the sync signals are all good, most monitors will refuse to display the RGB video from a IIgs. For testing purposes I bought a Samsung SyncMaster 512N specifically because it was reported to work at 15 kHz with the IIgs. Unfortunately it was a bust. The 512N’s activity LED would turn green and the backlight would turn on, but no picture would appear. The monitor’s front panel buttons were also unresponsive, as if the monitor firmware were frozen. I tried the IIgs’ RGB video in composite sync splitting mode, as well as sync-on-green and csync-to-hsync modes, with the same results every time. The failure in csync splitting mode could be a flaw with the Sync-inator, but the other modes should definitely have worked since this monitor supports 15 kHz as well as SOG and csync-to-hsync (I confirmed its sync support with some other video sources).

So I started doing some digging. In the manual for the 512N, it lists 30 kHz as the lowest supported refresh rate, not 15 kHz. Then I found a handy web page with a big list of older monitors and brief reports of their 15 kHz support. This page lists the 510N’s 15 kHz capabilities as “partial”. It doesn’t have an entry for the 512N, but I think they’re the same thing with and without audio speakers. The other SyncMasters in the same product series were also listed as “partial” or “no”.

After doing more reading, this leads me to believe that 15 kHz may be an undocumented feature that may only work on some 512N samples. Either Samsung changed the internal design during the product’s lifetime without changing the model number, or it’s a question of engineering tolerances and manufacturing variability whether 15 kHz works or not. In my case, the answer seems to be “not”.

Update: I later discovered that the IIgs was in PAL mode (50 Hz refresh). After switching the IIgs to 60 Hz vertical refresh, the 512N behaved identically to the VE228H described next.

 
A Second 15 kHz Monitor

But hang on, that handy web page also lists the Asus VE228H as having full 15 kHz support, and that just happens to be one of the eleven monitors in my growing fleet of test equipment. So I hooked up the VE228H in sync-on-green mode, and it worked! The title photo shows an Apple IIgs GS/OS desktop output via the Sync-inator on the VE228H. I also tried the mode where csync is sent to the monitor’s hsync input, and that worked too, even when I physically cut the green video line to be certain the monitor wasn’t sneakily using SOG.

Sadly the Sync-inator’s csync splitting mode didn’t work on the VE228H – mostly it just showed a blank screen or “out of range” error. That’s OK because csync splitting isn’t needed in this particular case, since one of the other sync modes can be used instead, but it meant that something wasn’t quite right with my 15 kHz csync-split signal. That might eventually be a problem in other settings with other monitors. I spent a long time fiddling with parameters and attempting to hand-tune the resulting sync signals to be as good as possible, and while I did succeed in getting the IIgs video to appear for brief moments, I never found a combination that worked reliably.

Is this a failure? Looking at that 15 kHz web page list again, most of the comments for monitors that worked say that they were tested with a simple passive adapter, without any fancy sync processing. The Sync-inator can do that too, as my tests showed. A 15 kHz csync splitting mode would only be relevant in cases where somebody has a IIgs and a 15 kHz monitor, but the monitor only supports 15 kHz on its separate hsync/vsync inputs and can’t support that same signal as sync-on-green or csync-to-hsync. The comments on the web page would suggest that’s a rare situation, maybe non-existent. Manufacturers that include 15 kHz support probably know that they’re targeting older computers and game consoles where composite sync and SOG are common.

Given all this, I’m planning to remove explicit IIgs support from the csync-splitting code, since it doesn’t work in its current incarnation, and since most of the time it should be possible to use another sync mode with the IIgs (assuming a 15 kHz monitor). Removing the IIgs-specific code would have other benefits too, slightly simplifying the main loop code for csync splitting and enabling it to run a bit faster, which might also help in other areas.

 
Status and Next Steps

With that, I think I’ve nearly reached the end of compatibility testing. One significant change made recently is the addition of a feature that dynamically changes the microcontroller’s system clock speed depending on the supply voltage it detects. The Sync-inator is normally self-powered, drawing its supply current from the sync signals themselves, and the supply voltage varies depending on the particular Mac or video card being used. Higher clock speeds require higher supply voltages. This clock speed adjustment allows for slightly more precise csync splitting behavior when sufficient voltage is available, but has no effect on the other passive sync translation modes.

“Normal” Mac-to-VGA adapter behaviors are now 100 percent working, including setting the desired video resolution through DIP switches, and choosing a passive sync translation mode. This matches the capabilities of other Mac-to-VGA adapters.

For troubleshooting help, the csync and hsync/vsync activity LEDs are working, and the serial port output is working. The default DIP switch setting for the sync mode is also “automatic”, which aims to reduce guesswork.

For the Mac IIci and IIsi, composite sync splitting is 100 percent working on every monitor that I’ve tested. That was my main goal, and it’s met. This enables the IIci and IIsi to work on a wider selection of monitors than before.

I’m fairly certain there aren’t any other Macintosh models whose built-in video doesn’t output separate hsync/vsync signals and that would benefit from csync splitting. Among plug-in video cards, I’ve only found a few early cards from the 1980s that don’t output separate hsync/vsync. For the Macintosh Monochrome Card, composite sync splitting with the Sync-inator is working out-of-the-box with 90 percent of monitors tested, and the one exception also works if an external 5V power supply is used. That’s great.

The Toby Nubus video card has a strangely different csync signal than others. It works with all of the monitors tested, but has a few quirks. For a small number of monitors, an external 5V supply for the Sync-inator is needed when using csync splitting mode. One “Planar” brand monitor balks at the csync splitting signals from the Toby, but automatically switches over to sync-on-green which works. I’d rate the csync splitting support for Toby as 4.5 out of 5 stars.

The SuperMac ColorCard SE/30 is another oddball. It fares similar to the Toby, working with all of the monitors tested but requiring a 5V Sync-inator supply when used with some fussier monitors. The benefit of a 5V supply appears to increase for higher resolution video modes. The Planar monitor behaves the same as with the Toby card, switching over to sync-on-green. I’d rate the csync splitting support for this SuperMac card as 4.5 out of 5 stars.

Although I’ve focused heavily on csync splitting in this discussion, most of the time csync splitting mode won’t be needed, because you’re not using a crusty old video source with composite sync or else because your monitor supports SOG or csync-to-hsync. Those common cases are completely working, 5 out of 5 stars.

I still need to clean up a few loose ends here, but I’m hoping I can finally finish this project soon.