Apple IIc Improvements

This week for #Appril2 we're looking at a couple of Apple IIc machines and making some ROM and keyboard improvements.
#Appril2 is an initiative to celebrate Apple ][ machines during the month of April in the spirit of MARCHintosh. Do check out the Appril2 website:
appril2.com/
Links
Apple //c Histrory:
www.apple2history.org/history...
Custom ROMs for the Apple IIc:
github.com/mgcaret/rom4x
Apple IIc LCD - Color Conversion (JavMaster)
Adventures in Retrocomputing Episode 44: Apple IIc Flat panel display LCD screen conversion
Disk Drives for the Apple II chart:
javmast3r/status/...
#retrocomputing

[@RudysRetroIntel]

Very nicely done, and thanks for sharing. Subscribed!

[@retrotechguy]

Thank you!

[@johneygd]

Well done.

[@martindoherty377]

Here's how I open the case of my IIc: 1) remove the 6 outer screws, 2) flip the handle down, 3) lift the back of the unit about 4 - 5 cm, 4) let it drop. The top of the case will pop off, no prying needed. Apparently this is quite safe for the internals and the technique was taught to Apple dealers in the 1980's.

[@retrotechguy]

Ok! Is sounds a bit brutal and I would be worried about the disk drive head alignment, but of it works…👍

[@tetsujin_144]

10:02 - (regarding mods to the machine) "bodge wire to the oscillator" The oscillator itself was not original I think. That's for the serial ports, early IIc's didn't have a dedicated oscillator for the serial ports, instead (in that position) they had a clock divider IC which created the serial port clock from the system's clock... but the resulting serial clock was about 3% too slow, meaning it could lose sync when talking to devices that were a little too fast. The oscillator itself is a mod. Whether it's a factory mod or a user mod, I don't know.

[@retrotechguy]

Ok, thanks - that’s very interesting. I’m thinking it was probably a factory bodge in that case. It looks very clean and exact.

[@ReedHansen84]

The enter key isn't the only difference I notice with the American, all the buttons besides "80/40" are icons instead. Cool to see the country differences, myself being headquartered in the US.

[@retrotechguy]

Yeah, I was surprised they’re so different!

[@AIM54A]

I still have my //c and it had a 3.5 drive.. sadly the powersupply died on it and fried the 3.5 drive.. Had to replace both, think I worked all summer to save up enough to get it repaired.. Never failed after that. Also did the hardware update with the 8Mhz cpu upgrade with more RAM. Good times.

[@retrotechguy]

Good job! The boards themselves seem pretty reliable.

[@ProfVonW]

Anyone else wish Apple would return to the Snow White Design Language?

[@retrotechguy]

Yes! 👍

[@jameswalker199]

I don't hate the silver metal of more recent macs, but it's feeling more and more soulless as time goes on. The Snow White design still feels corporate, but it's cheery corporate, like they let you wear a fun tie with your short sleeve shirt.

[@thisisreallyme3130]

Is there a secret handshake to getting those Apple IIc-VGA adapters? :-) I'm glad to see it reviewed here and elsewhere, but I have been trying to buy one for over 2 years: refreshing the store many times, putting it into my wish list, and even emailing the author.

[@retrotechguy]

Good question! :) I've been trying to find one myself, but I'm reconciling with the fact that I'll probably have to put one together myself withe the RGB2HDMI project...

[@thisisreallyme3130]

@@retrotechguy My understanding is on a IIc the RGB2HDMI won't decode the RGB. It will merely do composite-to-HDMI. Unless that's also what A2CVGA is doing (not what it says it is) the NTSC signal would not give as good of a picture as the RGB.

[@tetsujin_144]

@@thisisreallyme3130 The Apple II doesn't really put out RGB at all, it puts out 1-bit monochrome which NTSC monitors interpret as color modulation. Adapters like A2cVGA and RGB2HDMI (on Apple II) consume the system's monochrome output and in color mode they will convert pixel patterns to color in a way similar to how an NTSC monitor would do it. On the IIc in particular the video port at the back (15-pin) includes some additional signals that are helpful for synchronizing with the system's video output and detecting the bit 7 phase-shifting used to select the alternate color palette in hi-res mode, and a TTL-level version of the pixel data as it's being streamed out. With this kind of approach, there are a number of beneficial things an adapter like A2cVGA (or RGB2HDMI) can do, like switch between monochrome mode (no color conversion) and color mode (NTSC-like color conversion), automatic switching back to monochrome mode for the text portion of a mixed text-and-graphics display, and different options for specific details of how color is converted. So for instance one quirk about the old Apple II color is that certain colors directly adjacent to other colors will result in artifacts: The colors are made by alternating light/dark pixels at 3.5MHz, with the color determined by the phase of that oscillation relative to a reference signal. The monitor determines the brightness by applying an analog low-pass filter, and determines the hue by checking the phase. But if you have green ("01") next to purple ("10") it becomes "0110" and the low pass filter is likely to interpret the part in the middle as white, rather than a border between green and purple. Apple II graphics designers usually had to carefully design their graphics around this, but if the system had an RGB adapter it's likely that it wouldn't recreate those artifacts and instead just show green and purple directly adjacent. These modern adapters can do that too, or they can more closely emulate the behavior of a real NTSC display. Some old RGB adapters for the Apple II also supported different video modes: The Apple II's video system pulls a byte out of display RAM once every microsecond, and in graphics mode uses 7 bits of that byte as pixel data, and (in hi-res graphics mode) uses the 8th bit to decide whether to shift the timing of the pixel data by a quarter phase. This 7 bits * 80 character cells gives us the Apple's 560 pixel wide double hi-res graphics mode. However, some of those old RGB adapters could instead use all 8 bits as pixel data, creating either a 640 pixel wide monochrome mode, or having two 4-bit color values per byte (for a 160 pixel wide, 16-color mode, without the usual Apple II awkwardness of the color data for a single pixel spanning two different locations in memory). It would be possible to support such a mode with a device like A2cRGB or RGB2HDMI, but I don't think such modes are currently implemented. It's also worth noting that there were RGB adapters for the Apple IIc back in the 1980s: Devices like Le Chat Mauve or the Video 7 Color Enhancer. Tracking one of those down would also be an option if you want color without having to get an NTSC monitor.

[@MrKurtHaeusler]

Can't you get a color signal coming out of the RGB port? And wiring it straight up to that scart box on the wall? Or is that not normal RGB coming out of the IIc? Edit: I just read, its not RGB

[@retrotechguy]

Yeah, it really is hard getting colour out of PAL these machines. There is this solution involving a Raspberry Pi that I’m planning to look into in the future: github.com/hoglet67/RGBtoHDMI/wiki/Supported-Computers

[@RC-74]

I have a //c that I bought when they first came out. Used it to introduce computers to my sons. I would love to boot it up now, but I somehow cannot find the power brick and cabling. I am no electronics expert and don't have a clue for a workaround. Can anyone give me some advice? I would really appreciate it!

[@retrotechguy]

Great that you’ve kept it! I just posted a short with my DIY power brick for an Apple IIc set to 15 V, but you may be able to buy them on eBay assembled: kzbin.infouSdJlrEtRDE?feature=share

[@RC-74]

@@retrotechguy Thank you for the quick reply. I'll check out both approaches!

[@MrAlan1828]

You have the non Alps keyboard without key supports so most of the keys if not pressed in the center will stiff up. This is what I did, remove all the keys (wash scrub) removed the black rubbery mat, sprayed IPA onto the keyboard and toothbrush scrub all the keys, let dry and spray a non conductive lubricant like DeoxIT®, #D5S-6 (optional remove the metal clips on each key) leave the rubber mat out, its night and day experience. Still nowhere close to the ALPS keyboard

[@retrotechguy]

Yeah, the Alps ones must be great but the improvement without the rubber mat is awesome 👍