Thanks @640KB, you are correct. I've just checked and my BIOS is almost identical to Juko v2.20.This is most definitely a Juko ST, though likely a clone such as Flytek ST-12, Unique UX-12 or Auva BXM-12. It's based on the Tamarack TD3300A chipset which, according to the very little amount of documentation I've been able to find is spec'd to run up at 15MHz (though I'm not aware of anyone having ever produced physical evidence that such a board was actually manufactured).
It can take up to 1MB of RAM, however the ASIC does not have proper memory mapping so you are limited to using it with the supplied RAM disk driver or a user-made EMS driver (that is also subject to some of those limitations).
That BIOS is interesting as it is nearly identical to the Juko v2.20, except all of the Juko copyright and branding has been replaced by the string "TURBO XT".
It is definitely a nice XT board and should be quite fast at 12 MHz with that V20. Good score!
I've been running my -8 V20 at 12MHz forever on my own ST-12 and have never had any issues, heat or stability. They seem to overclock quite happily by most accounts.That's an 8 MHz V20 chip. Is the board overclocking it?
Does this board overclock v20 to 12 mhz by default? I don’t see any configuration to accomplish this, besides J3:I've been running my -8 V20 at 12MHz forever on my own ST-12 and have never had any issues, heat or stability. They seem to overclock quite happily by most accounts.
Love the reverse engineering project on it - would be very interested what you learn, especially with the hardware. I've been studying what I can find about the TD3300A chipset myself to see if there are any hidden capabilities that can be unlocked - such as useful access to the upper memory on board or if there is a way to configure the bus clock to be different than the CPU clock so the board could be run at the 15MHz that it claims it can do. Near as I can tell though, the answer is... no. It appears that the upper RAM can only be bank switched, swapping the 384k of memory that's between 128-512k with the otherwise unused 640-1024k on the board. Unfortunately, there doesn't seem to be any way to map any of it into any real UMA segments, so the utility is limited.
That's not the CPU's actual clock speed. Landmark is comparing it to the IBM AT and saying the CPU is performing like an AT running at 7.29 MHz.My guess is that 7.29 MHz is the most realistic one.
That's the same result I get on mine on Landmark (7.29) so yours is obviously clocked the same. My experience with benchmark programs that attempt to calculate clock rate is that Landmark 6.0 seems to be the most accurate (at least on XT systems), so I'd tend to trust the "12.087 MHz" as the best confirmation you'll probably get from software.Does this board overclock v20 to 12 mhz by default? I don’t see any configuration to accomplish this, besides J3:
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How do you know that the cpu is really running at 12 MHz. Which tool are you using to benchmark?
@640KB, I'll be happy to help identifying any undocumented feature of TD3300A. Do you know if somebody has fully reversed engineering this BIOS, or has uploaded the original asm source code for ST-12?Love the reverse engineering project on it - would be very interested what you learn, especially with the hardware. I've been studying what I can find about the TD3300A chipset myself to see if there are any hidden capabilities that can be unlocked - such as useful access to the upper memory on board or if there is a way to configure the bus clock to be different than the CPU clock so the board could be run at the 15MHz that it claims it can do. Near as I can tell though, the answer is... no. It appears that the upper RAM can only be bank switched, swapping the 384k of memory that's between 128-512k with the otherwise unused 640-1024k on the board. Unfortunately, there doesn't seem to be any way to map any of it into any real UMA segments, so the utility is limited.
640KB
PS: saw your section about testing with GLaBIOS - very cool. The ST-12 build fully supports TD3300A chipset features like turbo hotkeys and wait state configs -- in fact, the ST-12 is probably my favorite V20 board I own so I've put in a lot of time to tweak it up. Hence the research project to see if there are any possibly useful or even undocumented features that could be worked in to make it even better.
I see. So, that means this CPU is overclocked to 12 MHZ then.That's not the CPU's actual clock speed. Landmark is comparing it to the IBM AT and saying the CPU is performing like an AT running at 7.29 MHz.
BTW @640KB, I've just realized you are the creator of GLaBIOS. I left a question related to TD3300A in the repo. I would like to know how you found out how to setup reg 0x90; if you did that by reverse engineering the BIOS or if you found some documentation that describes this.