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Software-based floppy disc data separator

by classiccmp＠philpem.me.uk

Hi guys, Here's something for you lot to play with. It's a software implementation of the "Phase Jerked Loop" data separator, in C++ (although most of the logic is C), complete with notes... This is extremely sub-optimal, but "It Works For Me"... :) Tests against the old "Helix" decoder engine (the "smart" histogram analyser that really is anything but) are still ongoing. As a bare minimum, the timing figures need to be optimised -- most timesteps will end up with no accompanying state change. If you can eliminate some of these timesteps, you can speed up the code quite a bit. The catch is that the timestep must be a multiple of NSECS_PER_PLLCK/2, NSECS_PER_PLLCK and NSECS_PER_ACQ... The optimal value should be lcm(NSECS_PER_PLLCK/2, NSECS_PER_ACQ) [lcm = lowest common multiple]. Optimising the timing factors for a given acq-clock is likely to be the hardest part of the whole process... I'm willing to bet it'll work with data grabbed from a Catweasel, but I don't have any test data to play with... so that's left as an exercise to the reader. mfmbits is a vector<bool> which starts out empty and contains the output MFM bits after the loop has run. A sync marker will appear in mfmbits as 0x4489. buf is either an array or a vector containing integers of any sane size. These represent the timing values in units of Tacq (Tacq = 1/Facq, the frequency at which the acquisition counter is incremented). buflen is the length of this buffer. License is GPLv2, code is copyrighted to me. If you want to use this in closed-source software, email me and ask for a less restrictive licence. I'm getting pretty pissed off with people in the floppy disc preservation/analysis field keeping their toys to themselves (*cough* SPS), and have no intention of contributing further to such nonsense. > /** > * This is a software implementation of Jim Thompson's Phase-Jerked Loop > * design, available from AnalogInnovations.com as the PDF file > * "FloppyDataExtractor.pdf". > * > * This consists of: > * A data synchroniser which forces RD_DATA to be active for 2 clock cycles. > * A counter which increments constantly while the PLL is running, and is > * reset to zero on an incoming data bit. > * Whenever the counter reaches half of its maximum value, a > * new data window is started. > */ > > // Nanoseconds counters. Increment once per loop or "virtual" nanosecond > unsigned long nsecs1 = 0, nsecs2=0; > // Number of nanoseconds per acq tick -- (1/freq)*1e9. This is valid for 40MHz. > const unsigned long NSECS_PER_ACQ = 25; > // Number of nanoseconds per PLLCK tick -- (1/16e6)*1e9. 16MHz. > // This should be the reciprocal of 32 times the data rate in kbps, multiplied > // by 1e9 to get the time in nanoseconds. > const unsigned long NSECS_PER_PLLCK = 125/2; > // Number of clock increments per loop (timing granularity) > const unsigned long TIMER_INCREMENT = 1; > // Maximum value of the PJL counter. Determines the granularity of phase changes. > const unsigned char PJL_COUNTER_MAX = 16; > > // Iterator for data buffer > size_t i = 0; > > // True if RD_DATA was high in this clock cycle > bool rd_latch = false; > // Same but only active for 2Tcy (SHAPED_DATA) > int shaped_data = 0; > > // Phase Jerked Loop counter > unsigned char pjl_shifter = 0; > > // data window > unsigned char data_window = 0; > > #ifdef VCD > FILE *vcd = fopen("values.vcd", "wt"); > fprintf(vcd, "$version DiscFerret Analyser D2/DPLL 0.1 $end\n" > "$timescale 1 ns $end\n" > "$var reg 1 * clock $end\n" > "$var reg 1 ' pll_clock $end\n" > "$var reg 1 ! rd_data $end\n" > "$var reg 1 %% rd_data_latched $end\n" > "$var reg 1 ^ shaped_data $end\n" > "$var reg 8 & pjl_shifter $end\n" > "$var reg 1 ( data_window $end\n" > "$upscope $end\n" > "$enddefinitions $end\n" > "$dumpall\n" > "0*\n" > "0'\n" > "0!\n" > "0%%\n" > "0^\n" > "b00000000 &\n" > "0(\n" > "$end\n" > ); > #endif > do { > // Increment counters > nsecs1 += TIMER_INCREMENT; > nsecs2 += TIMER_INCREMENT; > > // Loop 1 -- floppy disc read channel > if (nsecs1 >= (buf[i] * NSECS_PER_ACQ)) { > // Flux transition. Set the read latches. > rd_latch = true; > shaped_data = 2; > > // Update nanoseconds counter for read channel, retain error factor > nsecs1 -= (buf[i] * NSECS_PER_ACQ); > > // Update buffer position > i++; > } > > // Loop 2 -- DPLL channel > if (nsecs2 >= NSECS_PER_PLLCK) { > // Update nanoseconds counter for PLL, retain error factor > nsecs2 -= NSECS_PER_PLLCK; > > // PJL loop > if (shaped_data > 0) { > pjl_shifter = 0; > } else { > // increment shifter > pjl_shifter = (pjl_shifter + 1) % PJL_COUNTER_MAX; > } > > // DWIN detect > if (pjl_shifter == (PJL_COUNTER_MAX / 2)) { > // Data window toggle. Latch the current RD_LATCH blob into the output buffer. > mfmbits.push_back(rd_latch); > // Clear the data latch ready for the next data window. > rd_latch = false; > // Update DWIN > data_window ^= 0x01; > } > > // Update shaped-data time counter > if (shaped_data > 0) shaped_data--; > } > } while (i < buflen); > > printf("mfmbits count = %lu\n", mfmbits.size()); -- Phil. classiccmp at philpem.me.uk http://www.philpem.me.uk/

15 years, 9 months

"The Paper" PET newsletter

by silent700＠gmail.com

Did anyone win this on ebay today? http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320547974650&ssPageName=… If so, do you plan on scanning it? If you scan, I will host. If you can't scan it and want me to, I will do so and send it back. -- jht

15 years, 9 months

FFS: SGI IP10 (Iris 4D) motherboard

by silent700＠gmail.com

The condition is unknown (other than not cracked and not rusty,) the box looks original, the RAM slots are empty, the ROM chips are labeled Boot 0 - Boot3, the zip code is 60074. Anyone want it? -- silent700.blogspot.com Retrocomputing and collecting in the Chicago area: http://chiclassiccomp.org

15 years, 9 months

Coleco ADAM Con - Montreal

by c.murray.mccullough＠gmail.com

Hi Everyone, A classic computer of the 8-bit era, the Coleco ADAM, is celebrated by all Adamites of Canada and the U.S.A., each year is winding up in Montreal, our 22 annual convention. The central part in my opinion is how to run an ADAM emulator on the PC. For those who still have a working ADAM, more power to you all. Happy classic computing! Murray :)

15 years, 9 months

joining cctalk

by dgriffi＠cs.csubak.edu

I referred someone to this mailing list, but he's unable to join. The server says that he needs to wait to be approved, but nothing happens. -- David Griffith dgriffi at cs.csubak.edu A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

15 years, 9 months

CS/SS-80 HP-IB Bering 8940 Econopac 4Gb on Ebay in CA

by rdbrown＠pacific.net.au

Bering 8940 Econopac 4gig Fixed Disk Drive rev. B S/N 0206A005 Item number:380244025020 Item location:Irwindale, CA, United States www.bering.com/doc/brochure/econopac.pdf www.bering.com/doc/man/econ8000.pdf

15 years, 9 months

Amiga 1200, some AV gear, and some test equipment from CL

by brianlanning＠gmail.com

I've been talking to someone who posted an amiga 1200 on craigs list. This is in the chicago area. She has a lot of AV and test equipment also. I have no relation to her, I'm just passing the list along incase anyone is interested. I'm also pasting in a description of the amiga from another thread. Contact her directly (Amy) for pics and details: smittygal7 at hotmail.com The seller replied with some pictures. It's a normal amiga 1200 with a GVP (jaws) 68EC030-40 accelerator without a scsi controller. Unknown ram. It's the model that didn't come with a hard drive, although one has almost certainly been added. There's a vga adapter on the back of the 1200, but it appears that it's not a flicker fixer. They probably had it attached to a monitor that would sync low enough. She's including a 1084s monitor with the machine. The tower has two time base corrector boards installed in what looks like an 8086 type clone motherboard. I'm guessing this because it has the fat 5150 style keyboard connector. Chances are, this motherboard is there only to make the power supply spin up and to provide ISA slots to power the TBC boards. I was hoping it was some sort of expansion chassis that could add zorro or video slots to a 1200, but no dice. 1. Datacom Technologies ET-2 V.35 Error Rate Test Set, brand new wtih manual, case, power pack, etc... 2. Used, Black Box SAM 232-60 3. Plantronics Wilcom Model T336B Circuit Test Set 4. ADK A Joslyn Company 720- TEST Adam-720 test set 1. SHARP XG-E1200U LCD Projector BRAND NEW in BOX w/REMOTE 2. Yamaha RX 595 Natural Sound 2ch stereo Reciever 3. Astrodesign Inc. Digital Video Generator VG-814 GREAT CONDITION, LIKE BRAND NEW 4. Plantronics Wilcom Digital Circuit Test Set M#:T336B 5. TOA-9000 Power Amp/Mixer/Matrix BRAND NEW IN BOX 6. SONY STR-GX800ES HI-FI FM/AM STEREO RECEIVER BRAND NEW 7. Pioneer VSX-3300 2-channel MONSTER Audio/video Receiver/Used in great condition 8. Technics Stereo RS-TR232 Double Cassette GREAT USED 9. Panasonic AG-1960 Pro-line Video Cassette Recorder 10. Onkyo TA-R401 Vintage Stereo Cassette Tape Deck RI 11. Realistic STA-116 Digital Synthesized AM/FM Stereo Reciever 12. Panasonic PV-S7670 BRAND NEW IN BOX SUPER VHS-VCR 13. Panasonic Omnivision Video Cassette Recorder PV-4464 Brand new in box 14. SENCORE CR70 UNIVERSAL CRT ANALYZER AND RESTORER 15. Panasonic Professional Video Cassette Player AG-5100-P new in box 16. Denon Audio CD/Cassette Combi-deck- BRAND NEW IN BOX 17. Tenma Monitor Tester 16 Scan Formats 72-1070 brand new 18. Tenma Dummy Loader 72-4060

15 years, 9 months

DEC RQZX1 and KDJ11-E boot problem?

by bqt＠softjar.se

"Zane H. Healy" <healyzh at aracnet.com> wrote: > Now for an interesting bit of info. Apparently there are two > different types of Firmware. One for the PDP-11, and one for VAXen. > I'll see if I can get a little bit more info on that. Huh? That sounds extremely weird, and until you find very good proof of that, I would say that it is false. In the end, it's a Qbus device, and talks Qbus just like anything else. It's also an MSCP controller, which means it talks MSCP, just like any other MSCP controller. And they work the same no matter if they are controlled by a VAX CPU or a PDP-11 CPU. > Now for the important part, the whole manual. > http://www.avanthar.com/~healyzh/RQZX1.pdf Excellent! Thanks for putting this up there. > Looking through the list of supported hardware I see where this is a > board that is of use to very few Hobbyists. It is interesting that > the older versions of the OS's can't support it, when they support > something like a Viking QDT just fine. It is worth pointing out that support OS versions is just a list of the versions that was current when the manual was written. That does not mean that the board don't work in previous versions. The RQZX1 is an MSCP/TMSCP controller, and thus will work with any OS version where the MSCP/TMSCP driver exist, and work. So, it's no different than the QDT, or any other MSCP controller. More or less the same is also true for disk drives. Most any SCSI drive will work fine. The same is probably also true for tape drives. Pros with the RQZX1: It's easy to set up. Switchpacks are easy and obvious. You can boot into the internal diagnostics. You have the option of 2*MSCP or MSCP+TMSCP. You have a floppy interface in there as well. Cons with the RQZX1: It's a quad board. No more than 4 disks on one controller. No more than one tape on a controller (it is rather inflexible). Still, if you have one, it's a nice board to have around. Johnny

15 years, 9 months

Post-VCF GB drink

by lproven＠gmail.com

If there're any VCF people about, a few of us are in the Park Hotel for a pint. MK2 2SN - just past the railway bridge. Sent from my Nokia phone

15 years, 9 months

DEC RQZX1 and KDJ11-E boot problem?

by nigel.d.williams＠gmail.com

On Thu, Jun 17, 2010 at 9:59 AM, Zane H. Healy <healyzh at aracnet.com> wrote: > Okay, here is what I learned. ?My comments are in parentheses. This is great! thanks for taking the time to chase this down. > 1. When writing an image out to the HD, you must have the exact same number > of blocks for the image and the HD. ?(This is why I'd suggested dd'ing the > HD to an image, using that image with SIMH to do the install, and then > dd'ing it back.) Ok, this is easy to test, I will report back with the results. > 4. RSTS/E might only support up to a 2GB drive (I use a 2GB drive). I will be using 1GB (or thereabouts) drive.

15 years, 9 months

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