Re: MELTDOWN and SPECTRE vulnerabilities and older hardware?

Posted on 2018-01-16, 13:59

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

It appears that these tools report 'vulnerable' when they detect an unpatched kernel. I would rather see a proof-of-concept that actually reads from kernel memory. That's the only way to prove whether a CPU is vulnerable.

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Re: DreamBlaster S2P : Small form factor General MIDI on parallel port

Posted on 2018-01-15, 23:25

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

Simple demonstration on my laptop: https://youtu.be/0f8vU1cLbQ4

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Re: DreamBlaster S2P : Small form factor General MIDI on parallel port

Posted on 2018-01-15, 22:58

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

Just tested my SoftMPU patch, it seems to work fine. I added a new switch /MT32 to enable MT-32 mode for the S2P. You can get the binary here: https://www.dropbox.com/s/v9tssu8k1samlf4/softmpu_s2p_mt32.zip?dl=0 I will see if I can make a pull request on Github to include the patch. Edit: pull …

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Re: DreamBlaster S2P : Small form factor General MIDI on parallel port

Posted on 2018-01-15, 21:06

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

I've made the necessary changes to SoftMPU to enable MT-32 mode... I'll have to test it though.

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Re: DreamBlaster S2P : Small form factor General MIDI on parallel port

Posted on 2018-01-15, 19:01

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

^ nice! is it the video or the experimental software/tsr to blame for notes that seem to play slower / out of sync? It's my quick hack MIDI player. I originally made it for the IMFC. I put in support for the DreamBlaster S2P, but it requires 3.5 microseconds of delay between commands. This is done …

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Re: DreamBlaster S2P : Small form factor General MIDI on parallel port

Posted on 2018-01-15, 18:37

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

I've done a quick-and-dirty MT-32 compatibility mode for my MIDI player, testing it with the Monkey Island soundtrack: https://youtu.be/3CXgt-tLod0 It shouldn't be too difficult to add this to SoftMPU. The DreamBlaster wants a CC 0 127 as a prefix for every PC command, to select an MT-32 instrument. …

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Re: DreamBlaster S2P : Small form factor General MIDI on parallel port

Posted on 2018-01-15, 16:38

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

Thanks for the work on SoftMPU, pdw! I tried to use my MIDI player as a test tool, and I got some sound out of it, but it was not correct. Now it seems that my main issue was that I really need to leave the USB power off the chip for a couple of seconds before it resets. So during my testing I often …

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Re: DreamBlaster S2P : Small form factor General MIDI on parallel port

Posted on 2018-01-14, 23:41

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

doesn't it take more cpu grunt to feed this with data over serial rather than paralytic? i remember trying a very small real time transfer on a k6-2 iirc over serial/paral - it was a disastrous slowdown In theory it doesn't, because you have a UART FIFO buffer. So you can just send bytes to the …

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Re: DreamBlaster S2P : Small form factor General MIDI on parallel port

Posted on 2018-01-14, 23:21

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

Wouldn't it make more sense to use the serial port in this case instead of the parallel port? The chip uses serial input anyway and it would leave the parallel port free for another device. Imagine to have a notebook with no soundcard, but a Dreamblaster on COM2 and a Covox on LPT. :D :D The chip …

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Re: TNDLPT : Tandy Sound on parallel port

Posted on 2018-01-13, 12:24

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

Hm James Design is using a clock divider right ? if isa bus is overclocked the SN Chip does runs with wrong clock It shouldn't be. There are two clock signals on the ISA bus, one is the actual bus clock (CLOCK). The other is a fixed NTSC clock (OSC): http://pinouts.ru/Slots/ISA_pinout.shtml The SN …

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Re: TNDLPT : Tandy Sound on parallel port

Posted on 2018-01-12, 19:37

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

Yes, but it says nothing about the oscillators. I suspect it's just for chip addressing as well, but I'd prefer not to guess. One of the errata of the lo-tech card deals with Chip Enable: https://www.lo-tech.co.uk/wiki/Lo-tech_Tandy_Compatible_Sound_Adapter IC1 pin 2 should be belt out (so it …

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Re: TNDLPT : Tandy Sound on parallel port

Posted on 2018-01-12, 19:01

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

It doesn't let you set a mask word for the tri state outputs, though, so either all pins are enabled or none. One thing I'm not clear on, though, and the datasheets don't say. Does the chip fully halt when CE is high or is it only pulled low when you want to strobe in more data? Of it's the latter, …

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Re: TNDLPT : Tandy Sound on parallel port

Posted on 2018-01-12, 13:49

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

I see. Certainly one of the simplest set of states possible. You'd still need latches and maybe tri-state buffers to (1) preserve bits like chip enable and (2) isolate the counter from the command pins when the sequence is complete. Yes, but I bet there's already some kind of 74xx IC that gives us …

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Re: TNDLPT : Tandy Sound on parallel port

Posted on 2018-01-12, 11:47

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

Flashing a uC is generally a lot easier than building a moderately complex pcb. Certainly not the same skill set, but it's a handy and useful thing to know how to do when working in embedded, so not generally a stretch to ask for it. It is? I have no idea how to flash a uC, or what kind of tools …

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Re: MELTDOWN and SPECTRE vulnerabilities and older hardware?

Posted on 2018-01-11, 22:56

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

goes back to the pentium 75mhz Yes, but that does not imply that they included new microcode for these processors. If you take the previous release, they also have that huge list of CPUs: https://downloadcenter.intel.com/download/26925/Linux-Processor-Microcode-Data-File So it seems that this is …

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Re: TNDLPT : Tandy Sound on parallel port

Posted on 2018-01-11, 22:19

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

If you really wanted with an ISA card you could add a small boot ROM to it so that it'll mute the chip very early in the boot process, you could also combine that with the transistor power-off trick, having the chip powered off until the boot ROM specifically enables it. Yes, but there are three …

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Re: TNDLPT : Tandy Sound on parallel port

Posted on 2018-01-11, 21:06

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

Yea, the parallel port would require some software to control it anyway, so having some startup code in the TSR would work fine for the TNDLPT. The problem is more with the ISA card. A real PCjr or Tandy has the 4 volume commands in the BIOS, so it shuts off as soon as the machine starts. Some …

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Re: TNDLPT : Tandy Sound on parallel port

Posted on 2018-01-11, 20:48

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

I would suggest something like a 4-bit counter (with a pair of inputs unused so it functions as a 2-bit adder) that controls a line driver whose inputs are connected to +5v. When the device is powered on or a reset button is pressed, this adder does its thing and between it and the driver those …

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Re: MELTDOWN and SPECTRE vulnerabilities and older hardware?

Posted on 2018-01-11, 10:47

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

No intel cpu since and including the Pentium Pro is safe to use unpatched. I wouldn't be too sure about that. I'd like to see a proof-of-concept being executed successfully on each CPU first. There is a difference between the CPU using speculative execution and it actually being exploitable as a …

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Re: TNDLPT : Tandy Sound on parallel port

Posted on 2018-01-11, 10:14

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

Couldn't that be overcome with a uC and buffer logic? Latch all the required pins inactive until sound output is required? Maybe I don't understand the issue. The problem is two-fold: 1) A uC requires programming, so it will be more difficult for people to build their own. They not only need to …

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