[Ted Fried] wrote in with not one but two (2!) new drop-in replacements for widespread old-school CPUs: the Zilog Z80 and the Intel 8088. Both of the “chips” run in cycle-accurate mode as well as in a super turbo mode, which can run so fast that you’ll need to use the Teensy’s internal RAM just to keep up.
Both of these designs have a hardware and software component. The PCBs basically adapt the pinout of the Teensy to the target CPU, with a bunch of 74VLC latches on board to do the voltage level conversion. The rest is a matter of emulating all of the instructions on the Teensy, which is more than fast enough to keep up. If this sounds familiar to you, it’s basically the same approach that [Ted] used last year to bring us his replacement for the 6502 found in the Apple ][ and Commodore 64.
Why would you want an emulated CPU when the originals are still available? [Ted] inherited a busted Osborne I, an ancient Z80 luggable. By replacing the original Z80 with his emulation, he could diagnose the entire system, which led him to discover some bad DRAM chips and get the old beast running again. Or maybe you just want to play IBM XT games at insane speeds?
And it looks like [Ted] has updated his 6502 emulation to include the undocumented C64 opcodes, so if you’re into that scene, you should be covered as well.
If any of this tickles your fancy, head over to [Ted]’s blog, microcore labs, and follow along. Although now that he’s covered most of the famous retrocomputers, we have to ask ourselves what processor is going to be next?
This is pretty amazing stuff – if you check the linked article you can see an IBM PC running this emulated CPU returning a Norton ‘SI’ rating of 11.7 – astounding !
+1
Too bad NEC V20 isn’t being emulated yet.
I guess ‘8080 emulation mode’ is simply too complicated to be implemented for now.
Give him time, he’s probably working on it, either that or the philosopher’s stone.
I’m sorry, it wasn’t meant to sound like a complaint. 😥
It rather was more of a conclusion.
Other projects haven’t managed emulating it, either, so far, it seems.
I considered adding V20 support but I don’t believe it would add enough to justify the effort. The additional opcodes are not needed by most software and I can achieve much more acceleration with the MCL86 than the small boost the V20 provides.
> [Ted] has updated his 6502 emulation to include the undocumented C64 opcodes
one entry prior is another great release – “Commodore 64 Tester using MCL64” where Ted exploited the fact his CPU emulator has full control over CPU bus to test every aspect of C64 beyond what old school deadtest cartridges are capable of
How about emulating the version of the TMS9900 in the TI 99/4A, but give it a lot more than 256 bytes CPU RAM?
The TI/994A was my very first computer! TMS9900 has a lot of pins which would be a challenge to emulate with the Teensy 4.1 Hmm…
I love this idea. There’s plenty of hardware that can accept a m68030 – I wonder if this could be squeezed into a teensy!
Whoops, sorry, apparently I can’t figure out how to computer today.
I’m having a hard time trying to RE the firmware from a chip with two (maybe three) 8051 cores. A dual 8051 core running on a teensy will be great since FPGAs is not an option for me.
+1