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A lot of special-purpose ICs are actually general-purpose processors with a mask ROM (or sometimes EEPROM, with interesting consequences), since writing the "firmware" for different functionality is easier than doing a whole "hard-coded" chip design --- the various USB-to-X adapters are one common example of this.
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> Woz's masterpiece, which was discrete logic It had the downside of requiring precise timing. This is an issue if you wanted a faster (or even a slightly improved) 6502 in the machine. Oh well...
This made me realize that Zip chips were a lot more complicated than kid-me thought: https://en.wikipedia.org/wiki/Apple_II_accelerators#Zip_Chip...
With current tech it should be trivial to keep all of the RAM in the module and just asynchronously push some writes out (video and IO) at Apple II speeds.
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Google Books shows the WD1771 available and in use in 1977 with more products using it in 1978. (I find Google Books very useful for this sort of archaeology. Change the time range to "1977-1980", search for "wd1771", and then sort by date. Of course this isn't thorough, but it gives a good overview for little effort.)
Thank you for the research. In that case I guess it’s more of a wrong bet on part choice in 1979 I guess.
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A few days ago, I brought an USB-to-serial chip made by an obscure manufacturer. I found the RX/TX ports were working but control signals were not, I poked around the chip with an oscilloscope and found those pins were high-impedance, the chip didn't even attempt to output anything. I contacted tech support. They told me to buy a new one because my chip was an old batch without this feature (I guess it's a bug), but…
It's the same situation with USB Bluetooth dongles - many purport to be based on a Cambridge Silicon Radio (CSR - now owned by Qualcomm) chip, but are in fact using one of several cheap alternatives. Many of these clones have their own quirks, and the amount of work-arounding that's been added to the Linux drivers is quite notable. Kernel 8.5 onwards seems to incorporate most of the fixes, but along the way, patches…
I love these die shot RE walkthroughs. This is such a weird choice though; almost no one used this chip for production hardware. The WD 17xx series was the king of floppy controllers in the 70's and early 80's (well, if you ignore Woz's masterpiece, which was discrete logic). Seems like if you're going to reverse an obscure chip, something with a more exotic application would have been more fun?
> Woz's masterpiece, which was discrete logic It had the downside of requiring precise timing. This is an issue if you wanted a faster (or even a slightly improved) 6502 in the machine. Oh well...
No, the Disk II was absolutely a masterpiece. Go back to the linked article, think about everything this very complicated chip did, and recognize that Woz made a card that did exactly the same thing out of 6 chips you could buy at Radio Shack and two tiny ROMs.
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A few days ago, I brought an USB-to-serial chip made by an obscure manufacturer. I found the RX/TX ports were working but control signals were not, I poked around the chip with an oscilloscope and found those pins were high-impedance, the chip didn't even attempt to output anything. I contacted tech support. They told me to buy a new one because my chip was an old batch without this feature (I guess it's a bug), but…
They are better though: the clones fixed bugs that the original FTDIs had (bugs bad enough to make certain modes completely useless). https://twitter.com/marcan42/status/695292366639378433?s=19 Don't buy FTDI chips; their malicious driver incident that bricked clones (by exploiting another bug in the EEPROM write support in their own chips!) should be enough to convince every board designer to stay away from them.
I love these die shot RE walkthroughs. This is such a weird choice though; almost no one used this chip for production hardware. The WD 17xx series was the king of floppy controllers in the 70's and early 80's (well, if you ignore Woz's masterpiece, which was discrete logic). Seems like if you're going to reverse an obscure chip, something with a more exotic application would have been more fun?
We definitely wanted fun! I guess there are two ways to slice and dice it: 1) fun because the application is exotic / iconic, or 2) fun because the chip is exotic. This is definitely a case of the latter: an exotic chip with interesting history.
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They are better though: the clones fixed bugs that the original FTDIs had (bugs bad enough to make certain modes completely useless). https://twitter.com/marcan42/status/695292366639378433?s=19 Don't buy FTDI chips; their malicious driver incident that bricked clones (by exploiting another bug in the EEPROM write support in their own chips!) should be enough to convince every board designer to stay away from them.
I needed a USB to serial converter and specifically went out of my way to ensure I did not purchase a FTDI based one exactly because of that malicious driver incident.
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> Woz's masterpiece, which was discrete logic It had the downside of requiring precise timing. This is an issue if you wanted a faster (or even a slightly improved) 6502 in the machine. Oh well...
None of the Apple II's competitors exploited that, though. EVERYTHING in that world of software was built around tight hardware assumptions. Atari, VIC, Commodore, none of them ever shipped a faster CPU. That needed to wait for later architectures. No, the Disk II was absolutely a masterpiece. Go back to the linked article, think about everything this very complicated chip did, and recognize that Woz made a card that…
I don't consider it a mistake - nobody at the time was realizing that we all would, eventually, move our software to faster computers every couple years. Woz is brilliant, but he couldn't have foreseen it and, as you point out, almost nobody did.