test-drb

test-drb@ccmp.vtda.org

101090 discussions

by allisonp＠world.std.com

< I've been sketching ideas based on a rocker that is threaded on a rod. T Smooth rod with a return spring and seperators between teh switches. < back of the rocker contains a 'paddle' which when the rocker is down, < breaks an IR/detector gap. This has a couple of benefits. One the rocker No question it's more reliable... what about dust. How about hall effect switches? < switch register - what size? Could have 8 to 32 bits if we wanted Number of bits is based on CPU native word size. < I've about half decided to build something PDP-8 like out of PIC chips. < They are relatively cheap, easy to program, and quite fast. I hadn't < thought about using them as base units (microcode sequencer, ALU control < etc) until this discussion began, but it also raised the point of Doable but not many are needed as the 8 series had a single accumularot and the amount of random logic that is not control related is small. < 'emulators' and I began to wonder what if you build a Z80 system that < emulated a PDP-8 with one of these custom front panels. That turns out t < be more of a software effort than a hardware effort. It was done on an 8080 in the mid 70s using a terminal as a text graphics display. < You can get PC boards made fairly cheaply, if you wanted to do a transis < based CPU I would definitely consider having a few hundred 'flip chip' < equivalents made. It wouldn't have to be 1:1 DEC replacements but they < showed it could be done. Wiring up 12 flip flops by hand on a piece of p < board (4 transistors each!) would be extremely painful. Yes it would also the shear number even at a penny(US) each would scare most people as something like an straight-8 used a few thousand. Resistors aren't cheap nor caps so that scales up real fast. Transistors if used would be a good thing for doing a serial machine as they have lower parts counts and few hardware "registers". Not modern silicone transistors do not have close to similar characteristics to the old grown junction or MADT germainium devices so circuit chages would be required. < First, find a 50Amp 5 volt supply. :-) The thing about TTL logic that < always amazes me is how much power it draws. I built a digital PLL out o < TTL chips once (about 40 chips) it was easily drawing 3-4 amps at speed < 74HC logic might be a good compromise here. I've done some heafty TTL designs (one was 200 chips SSI and some MSI) and it didn't need near 20 amps never mind 50. I don't thing the 8E PS can do more than 35A. Besides a simple design is possible without meltdown for heat. < computers called the 'beer budget graphics display' and was featured in < BYTE magazine in the late 70's. Basically this was two R2R D/A ladders < driving the X/Y inputs to an oscilloscope. If you make a 12 bit machine < could build a 4K x 4K resolution display fairly easily. (You will be cor I built it using a 8bit R2R ladder and that is the limit of that design for a lot of reasons. It settles slow (more than 10uS settling time) and the high order drivers to the R2R ladder have to supply some power. A later published design used 8bit moto1408, also slow. Or scale back to 1024x1024. This is known as vector graphics and the real limitation is how many vectors can you draw before you have to go back and redraw (flicker/refresh) which is a fuction of DAC speed, CPU speed and crt driver speed. It was the display common to the PDP-1, and seen on 8s and even some 11s for early graphics. Allison

27 years, 11 months

Corrections to trivia

by allisonp＠world.std.com

< I'm not sure how useful a definition it is. Why, for instance, isn't m < PDP-8/I considered to be microprocessor-based? It has a multi-chip < processor. So did the IBM 360/30, for that matter. The 8I was a TTL cpu and was a lot of DEC cards interconnected to make a minicomputer. There is no one board, or 15, in an 8I that could be called the CPU or even the core processor. The 8E did reduce that to three cards timing, major registers, major registers control. The dividing line is level of integration. The F14 CADC basically put those three 8E card into one ot two chips. < While I would be the last person to want to downplay the significance o < the F-14 computer, I personally think that the word 'microprocessor' is < only useful if it refers to a single monolithic IC, in which case Ted Ho < and Intel get credit for the first one. Microprocessor is a functional name ie: what it do, not what it are. So in most senses microcomputer and microprocessor are one and the same but not always interchangeable. Allison

27 years, 11 months

Corrections to trivia

by allisonp＠world.std.com

< Yes, but DEC had a strange definition of 'microprocessor'. They sometime < used the term to mean 'microcoded processor' - as in the microprocessor < board for the DMC11, etc which certainly wasn't a single-chip processor < (it was a hex-height card of TTL). Microprocessor... the RX01 disk controller (drive end) is a board of ttl and proms. It is a micro, meaning small, processor, it performs a set procedure of actions "process" upon data or system (disks and the data for them). The RX01 contains a microprogrammed microcontroller as its microprocessor. I'd think that was clear enough. ;) Allison

27 years, 11 months

Lisa HELP!

by kaikal＠MICROSOFT.com

Help! This is a weird one. I have a Sun Remarketing Macintosh XL (a.k.a. Lisa 2 modified). It has Sun's Parallel-to-SCSI card which runs a ribbon cable out the back of the machine and plugs into the external parallel port. OK, I've heard of such configurations, so far, so good. Problem is, neither the Kalok SCSI hard drive nor the 800K floppy drive spin up when I power on the machine. I pulled out the drive enclosure, and there is no power connected. The Sun Parallel-to-SCSI has a 6-pin right-angle power connector on it. There is a loose power connector in the drive area, but it has only 3 pins on a totally different spacing. What is going on here? thanks!! Kai

27 years, 11 months

Corrections to trivia

by allisonp＠world.std.com

< Sam wrote: < > Anyway, the F14 CADC SLF chip can be classified as a single-chip < > microprocessor. I say "can" because you've get a different definition < > microprocessor depending on whom you ask. < < OK, let us know the definition, so that we can decide whether the LSI-1 < chip set also qualifies as a microprocessor. Then we can settle the tri < question regarding which microprocessor-based Unix system came first. Dec sold the LSI-11 and later chip based systems as microcomputers. Source for this is the bindings of not less than 7 databooks and technical descriptions. Also the T-11 member of the family is a single 40pin dip with one die inside. If that werent' the case the fairchild F8 would not qualify as a single chip CPU due to the need for multiple chips and the same would apply to the predecessor to the RCA CDP1802. allison

27 years, 11 months

Cheap "variac"?

by cmcmanis＠freegate.com

Sam, if you need an example you can go to Halted in Sunnyvale and look on their row next to the test bench. They have a 20Amp 120v Variac on the shelf. It's about 8" around with a funky steering wheel like knob on the end. (they want $350 for it so its probably still there ;-) --Chuck

27 years, 11 months

Top 10 Holy Grails of Classic Microcomputer Collecting

by sethm＠loomcom.com

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27 years, 11 months

Working PDP-10 anyone?

by bill＠chipware.com

Already looking for next years VCF door prize? -----Original Message----- From: Sam Ismail [SMTP:dastar@ncal.verio.com] Sent: Monday, October 05, 1998 3:33 AM To: Discussion re-collecting of classic computers Subject: Working PDP-10 anyone? Does anyone know off-hand where there might be a complete, working PDP-10 system? Sam Alternate e-mail: dastar(a)siconic.com ------------------------------------------------------------------------------- Ever onward. Coming in 1999: Vintage Computer Festival 3.0 See http://www.vintage.org/vcf for details! [Last web site update: 09/21/98]

27 years, 11 months

FW: pdp11/44 free to good home in TX

by jfoust＠threedee.com

At 04:34 PM 10/3/98 -0700, you wrote: > >I'm telling you, its the Y2K scare. You'll start to see more and more of >this hardware become available as people start to panic. I'm frightened to realize that you're serious. Great, let's start scaring them even more, to increase our collections. :-) - John

27 years, 11 months

They still use Commodores in Nova Scotia

by rax＠warbaby.com

Surfing the back alleys of the Internet today, I found an ISP in Nova Scotia that has downloads of Internet access and utilities software for Commodores, Apple II's, and Atari's. Cool. Chebucto Net http://ccn.cs.dal.ca The download page is at http://ccn.cs.dal.ca/Services/PDA/PDA.html -- Warbaby The WebSite. The Domain. The Empire. http://www.warbaby.com The MonkeyPool WebSite Content Development http://www.monkeypool.com Once you get the nose on, the rest is just makeup.

27 years, 11 months

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