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Also, FYI, it was originally a Levco product -- like the ProdigySE and SpeedCard boards. It has 32 256Kx8s (1Mb of RAM) and 2 PALs (the 2 logic parts at the bottom that are placed vertically) for doing the address mapping.

RAM upgrades were incredibly expensive in 1987-88 and Apple was at the head of the pack on price. In the very early versions of SuperMac RAM upgrades, I think there was some soldering involved. It's how SuperMac originally got started. And before the OnePlusOne, Enhance and soldered upgrades...

My post above should say EEPROM (not EEROM). Maybe a friendly mod will edit it for me.

It's a 27C128 28-Pin DIP EEROM. In your programmer you should be able to choose a vendor and part number/type. It doesn't look like you're looking in the right place. The part you want is not on that list - that is a list of PIC chips (Microchip microcontrollers). Also, I guess there are DIP PIC...

OK - so a Spectrum/8 (Rev B) board (which was not infinitely programmable - the clock cap was just a little over 64Mhz with /16 divider on the TMS34061). Have fun with your project...or just look for a compatible RGB->HDMI adapter to convert RGB Sync-On-Green. I think that board also has a...

Trash - my comments are not necessarily restricted to specific cards. If there were a DB15-to-HDMI 1080p video converter that happened to recognize all the standard analog timings, it would accomplish what you are suggesting without having to bit-bang anything and/or rework every board to try to...

And just to clarify, when I open by saying "the best timing to use [for] 1080p would be 1024x768 19" 60Hz mode (not 13" 640x480)," I am talking about running it through a converter, as the post later outlines.

@Trash80toHP_Mini What you are considering would be very difficult to achieve or just end up being a huge waste of time. If I recall correctly, the VDTs on that board are (h x v): 1024x1536, 2048x1536 and 4096x1536. 640x480 13" mode probably also includes 1024x768. Anyway, the best timing...

I understand what you are saying -- context, etc. -- just a bit non-standard. ;) SCREEN RESOLUTION generally refers to the XY screen size and/or DPI rating. BIT DEPTH generally refers to the bit-per-pixel setting, which is tied to the physical amount of VRAM. However, as we are discussing...

The RAMDAC controls color output at various frequencies. For 8-bit video, you only need a single-channel 8-bit DAC (e.g. BT or AD478). For 24-bit (millions), you need a triple channel 8-bit DAC (e.g. BT or AD473) -- or 3 single-channel 8-bit ones. Also, the BT47x variants were faster and the...

@Arbee OK -- gotcha. I will look into it. Intuitively, it seems like MAME mappings would be a good application for ML/AI vs. Python or trying to render transistor layouts by hand (go into a cave and come out 10 years later :D ).

@Arbee Gotcha. I am curious to learn more about MAME when I have some time -- especially how it subsumes 68K interrupts and other vector-table-related activities. It seems like there are a lot of different 68K cores. @Aeroform For the SE/30 config issue, just boot from a 6.0.5 system disk to...

@Arbee OK - thanks. What 68K MAME core are you running? @Aeroform - You are correct that the cards are identical. The ColorCard SE/30 (codename: Pugsley) was such a low-volume product that it wasn't worth having separate hardware vs. the base Spectrum/8 Series II SE/30 board (codename: Astro)...

By "reg spies," I mean setting up monitoring to watch registers and break on some condition being true. That kind of strategy may not catch the exact moment of a real-time failure, but it might work well as a terminator for a multi-source log so that you know where to start looking as you back...

All QuickDraw coordinates are 16 bits (words). And, if you mapping things on the hardware side, you can expect that there will be 32-bit calculations to determine real physical addresses based on the board base address, which would be $fx000000 (32-bit mode) or $fxx00000 (24-bit mode). However...

Maybe you got it this time. 🤞

@Arbee No - I don't think so. To see the ROM, just bit invert it. There shouldn't be any issues in terms of the acceleration code. It works when running on a Mac, so maybe it is on the MAME side -- possible sign extension problem/issue somewhere?

Apple (also) published the source to an example video declaration ROM in Cards and Drivers. It was in their interest to help all 3rd parties develop video board products and to promote a diverse and competitive ecosystem. They tried to help developers see what might be possible (e.g. 8•24GC...

SuperMac's acceleration code was fairly robust and was intentionally built into the ROM (as part of the video driver). The ROM also included all the pan and zoom functionality and other advanced features, including VDI in later boards. Developers shouldn't make the (restrictive) assumption that...

re: am29K. Right - The 8•24GC was an expensive beast to behold (and to hold in your hands - quite a heavy board). Anyway, I was momentarily confused and misread your post. Sorry about that. And in thinking about it further, I remembered that the ProofPositive actually used the MIPS R3000A...