test-drb

test-drb@ccmp.vtda.org

101090 discussions

by mattislind＠gmail.com

I just recently had a RXV21 board that I inserted into the backplane and then completely hung a few bits on the bus. It was a DC005 bus transceiver chip that had failed. First it seemed impossible to find such a chip, but then I recognized that Signetics had put their own code own them as well, C2324N. Searching on Ebay gave this result: http://www.ebay.com/itm/281679682476 I bought some and they just arrived and worked perfectly. /Mattis

10 years, 4 months

QIC Tape help with CRC - Dwight?

by microtechdart＠gmail.com

While I'm new to speak up here, I've been watching for a while. I've also used the name "MightyFrame" on groups, although that email address is not registered with this list. A few months back, I published a page decoding QIC-24 format. http://mightyframe.blogspot.com/2015/08/qic-24-tape-data-block-format-decod… Dwight posted a very meaningful response to this about the CRC on my site, and it has taken me this long just to get to it. Thanks again for that, Dwight! This project has gone very well for me, with one hangup...the CRC. I've never calculated one of these before, and I'm struggling with this one. I have a QIC-24 block of data attached in a .txt file, and I just can't get the calculations to work. For my simple understanding so far, I'm using an online calculator to test this: http://bit.ly/1YbHUZ7 That URL is pre-programmed with the polynomial and the "message" that should provide the CRC result of 0xE8CE (decimal 59598) But, it doesn't. I created this file, wrote it to tape, then read it again and tested it. It is 100% correct for the QIC-24 tape system. This is block 3 of 4 of the file that I have extracted, and am testing here. The ANSI QIC-24 standard booklet (X3.136-1986) says something that I know is a clue, but I just don't understand. "The cyclical redundancy check (CRC) shall consist of two bytes, calculated over the 512 bytes of interchange data, and the 4-byte block address, *starting with all ONEs, CRC initial value*, and using the CRC Generating polynomial: x16 + x12 + x5 + 1 *"starting with all ONEs, CRC initial value"*? What does THAT mean? Do I need to do some kind of register shift? xorin or xorout? I've even played with http://reveng.sourceforge.net/, but I'm having trouble even understanding the meaning of the input values and parameters with this. I appreciate any feedback that anyone can give, here. -- Thanks, -AJ http://MicrotechM1.blogspot.com http://MightyFrame.com

10 years, 4 months

TOP POSTING (was: RE: Best 200 buck I have ever spent!!! Deal of a lifetime!!!

by cctalk＠beyondthepale.ie

> > This is a bit like the old toilet seat up/down argument... > > On Dec 9, 2015, at 3:58 PM, Jay West wrote: > > > Please make an effort not to top-post :| > > > > J > > > > After reviewing the 61 posts from the list I received this morning, I can only conclude that Johnny Billquist had the right idea. Regards, Peter Coghlan.

10 years, 4 months

New Special Project

by rodsmallwood52＠btinternet.com

Hi All I am working on a new special project. I can't reveal what it is yet. But I can tell you the bell is finished in polished brass with electromechanical striker and the whistle has its own air supply. Rod If you understand this and you are not out to grass (retired) like me you may want to consider it.

10 years, 4 months

CREEPYPASTA

by tulsamike3434＠gmail.com

What is your favorite CREEPYPASTA? I read one tonight called exploration of room -B. . . What are your fav'z? I am not a fan of the ones about games or the lame ones like Jeff the killer, Slenderman, Five nights at Freddy's ecp for the one called " The one in Crystal Cove". I am a big fan of Natenator77 and Otis Jiry "Chilling Tales For Dark Nights"!!! For those of you who do not know what creepypasta's are google it ot check out creepypasta.com . . I think this will be a great thread!

10 years, 4 months

AppleWorks for the Apple II

by tulsamike3434＠gmail.com

Does anyone here still use Apple Works for day to day use? I find it very useful it has a great word processor and a database / spreadsheet I use it to write Creepypastas in my Motorcycle shop late at night.

10 years, 4 months

Best 200 buck I have ever spent!!! Deal of a lifetime!!!

by COURYHOUSE＠aol.com

many high paid cios started with a vic 20 or a c 64! everyone has their treasured first.... Ed# In a message dated 12/9/2015 11:34:32 P.M. US Mountain Standard Time, mhs.stein at gmail.com writes: Surprised to see so much interest in C64s on a 'serious' list... m

10 years, 4 months

Four-phase non-overlapping clock generator using PIC microcontroller

by spacewar＠gmail.com

In the 1970s, some microprocessors and support chips used four-phase NMOS logic. Some, including the Rockwell PPS-4 and PPS-8, generated the four non-overlapping clock phases on-chip based on two external clock inputs, while others, including the TI TMS9900, the Western Digital CP1600 chip set (used in DEC LSI-11 and Alpha Micro AM100), and the WD9000 chipset (used in Pascal Microengine), required an external four-phase clock generator. Typically the four-phase clock inputs required a voltage swing close to the Vss and Vdd supply rails (0 to +12V). TI and Western Digital offered support chips to generate the four-phase clock, although it was often done with a crystal, 74S logic, and MOS drivers such as the National Semiconductor MH0026 dual MOS driver or the Intel 3245 quad MOS driver. I've recently had occasion to work on interfacing to some of these old chips, and wanted a modern four-phase clock generator. I've just written and tested code to use a Microchip PIC16F1575 as a clock generator, though it only has 5V outputs, so it will require external gate drivers, such as a Microchip TC4469 quad gate driver, to obtain the 12V swing. The PIC16F1575 is a fairly new part using Microchip's enhanced midrange core. It is in a 14-pin package, has an internal oscillator, PLL, and four 16-bit PWM modules. The PWM modules can operate independently, but for this purpose it was convenient that they can be synchronized. I've configured the PIC to use the 8 MHz internal oscillator, with a 4x PLL for a 32 MHz clock going into the processor and the PWM modules. The CPU speed doesn't matter, but that gives timing resolution of around 31ns for the PWM. I've configured the PWMs for a period of 16 clock cycles (500 ns, 2 MHz), clock high pulses of three clock cycles (93ns), and delay between phases of one clock cycle (31ns). This could be trivially changed to a 2.67 MHz clock by reducing the period to 12 cycles and hte clock high pulses to two clock cycles (62ns). Either set of timings is within the specifications of the TI and Western Digital parts. A word of caution: when using gate drivers to drive old NMOS parts, I recommend the use of series resistors of at least 10 ohms and schottky diode clamps to Vss and Vdd, to ensure that undershoot and overshoot (due to ringing) are limited to 0.3V. The C source code is released under the GPLv3 license on github: https://github.com/brouhaha/4phaseclk

10 years, 4 months

DEC MM15 core mem found

by j_hoppe＠t-online.de

I help cleaning out a large repository of DEC parts. There a quantity of DEC core module assemblies appeared. According to PDF docs these must be PDP-15 MM15's, but no labels are on the boards. I show/offer some of them at retrocmp.com/flipchipshop , under "core memory" Can somebody confirm they are MM15's? Are any PDP-15 running at all? Thanks, Joerg

10 years, 4 months

CDC Finch Alternatives Today [WAS:RE: Evotek Winchester Harddisk]

by t.gardner＠computer.org

The manual u cited states, "The disk controller can control either a CDC or Finch drives. All drives attached to any controller must be of one type." I'm not sure what they mean by "CDC" but if u are lucky it might mean "SMD." According to the 1983 Disk/Trend Finch interfaces were available on the Wren 9415-32 (Finch and ST506) and the Wren 94153 (Finch only). So u might look for a 94153 or a Finch variant of the 9415-32. The Finch spec data interface specs include 13440 unformatted bytes per revolution using an 806 KB/sec data rate, which are the very old at that time 3330 industry standards. There are very few small drives that use this standard, not even the 94153 (10,080 @ 605 KB/sec) so what happens with the drive at a different frequency and the controller with a possibly a different number of raw bytes per track is unpredictable. Note that 10080 x 806/605 is close enough to 13440 so any 10,080 @ 605 KB/sec drive might be made to work if the recording channel has margin at the higher frequency; unfortunately there are not very many. A bigger problem might be the command and control interface of the Finch - it is not like the ST506/412. Off the top of my head it looks like a variant on SMD. BTW SMD data specs are exactly 1.5x3330, that is 20,160 bytes @ 1.209 MB/sec so a small SMD might work if the recoding channel can deal with the lower data rate, perhaps the 8715 FSD. You might want to compare pin by pin SMD to Finch to see if this is even possible. There were some small SMDs, e.g. Micropolis 1403, Priam 804 but most were 14-inch. Perhaps there is a CDC SMD expert in this group that can help Tom -----Original Message----- From: Oliver Lehmann [mailto:lehmann at ans-netz.de] Sent: Monday, December 07, 2015 11:39 AM To: General Discussion: On-Topic and Off-Topic Posts Subject: Re: Evotek Winchester Harddisk Tom Gardner <t.gardner at computer.org> wrote: > Sorry If I didn't make myself clear, I am suggesting one never acquire > an Evotek drive today other than perhaps as an historical curiosity. > > > > The Finch was a short lived 8-inch HDD that went up to 42 MB > unformatted BUT according to Disk/Trend It did not use an ST506 > interface but instead came with this variety of interfaces: Finch, > LDI, SMD or SA1000! So your problem is likely to be finding a drive > that matches the interface of yr controller card. Some possibilities > > Finch interface was available on certain CDC Wren 5 -inch > models, e.g. 9415 > From what I understood in the Zilog System 8000 manuals, it is the Finch interface. http://bitsavers.informatik.uni-stuttgart.de/pdf/zilog/s8000/03-3237-04_hwR… Page 33 - Drive Performance Characterstics Page 47 - Pinout of the WDC-Controller Disk Connector Page 65-69 - Describing Driver Configurations Here are pictures of harddisks used in the System 8000: http://pics.pofo.de/gallery3/index.php/S8000/Harddisk And this is the so called "FINCH Adapter Board" used in the S8000: http://pics.pofo.de/gallery3/index.php/S8000/S8000_boards/FINCH-Adapter-Boa…

10 years, 4 months

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