test-drb May 2001

test-drb@ccmp.vtda.org

273 participants
642 discussions

by djg＠drs-esg.com

From: Jim Strickland <jim(a)calico.litterbox.com> >So I'm a 'scope newbie, does the probe impedance (13 pf) have to match the >rating on the jack on the scope (47 pf) for the waves coming out of the >calibration jack to be properly square? And if so, does anyone have a source >for probes that work with ancient scopes like this? > Most probes can be adjusted to work with a range of capacitance, they normally have a little adjustment hole at the end that attaches to the scope. Adjust it for the flattest trace. >Also, how do I tell a 535a from a 545a? > Look above the CRT and see if it says TYPE 535 or TYPE 545? I assume this is a big old tube scope, if not ignore the rest. >From Oscilloscopes, Selecting and Restoring a Classic by Stan Griffiths the 535A is 15MHz bandpass 5MHz trigger. 545A 33 MHz bandpass 5 MHz trigger. Bandpass may be less depending on what plugin is installed. I have a 547 (50 MHz bandpass and trigger) which I use to maintain my PDP-8's. Mine is a nice scopes but can be a little temperamental. Depending on what you are using it for the limited bandwidth (especially trigger) may be an issue. David Gesswein http://www.pdp8.net/ -- Run an old computer with blinkenlights

24 years, 1 month

TVs Undercurrents report on JIMs computer garage/classic computer collecting, who wants to see this?

by claudew＠videotron.ca

Hi all I taped the re-braodcast of this today. I am thinking of transfering this to a multimedia file and dumping it somewhere, it's about 5-10 minutes and does not go indept on the "hobby" but it's kinda fun and I think Jim has a few good "quotes" in there...about the hobby, computers and the vintage "market".... Now I only have to check to see if I have something around here to transfer this to a file... Claude http://computer_collector.tripod.com

24 years, 1 month

How many transistors in the 6502 processor?

by ajp166＠bellatlantic.net

From: Mike Cheponis <mac(a)Wireless.Com> Reordered your list by transistor count and added caveats... >From Microprocessor Report, in chronological order: > >8008: 3.5K transistors 14 mm^2 >1802: 5K transistors 27 mm^2 if 1802 were done in Nmos it would have been far lower transistor count. As it is CMOS there are many cases in the logic where two complmentary transistors exist where NMOS would have used one. It is also the ONLY one on the list that was fully static logic. Its registers used a lot of transistors as the raw flipflop. >6502: 4K transistors 21 mm^2 fewer transistors and also a clever design made for an easy mask that had good yeild for the die size. >6800: 4.1K transistors 16 mm^2 >8080: 4.8K transistors 20 mm^2 >8085: 6.5K transistors 20 mm^2 >Z80: 8.5K transistors 18 mm^2 >6809: 9K transistors 21 mm^2 >Z8001 17.5K transistors 39 mm^2 >8086: 29K transistors 33 mm^2 >8088: 29K transistors 33 mm^2 >68000 68K transistors 44 mm^2 >I really hate to interrupt this group's speculation with actual data, but >I'm weird in that way. Thanks, it's not as if the data was a top secret. Allison

24 years, 1 month

How many transistors in the 6502 processor?

by ajp166＠bellatlantic.net

From: Richard Erlacher <edick(a)idcomm.com> No question the 6502 was fewer gates than z80/6800 as that was the guys to chase. The 8080 was hard to hit as the 8080 required so much more external support that any of the 5V only cpus. It would be more fair to compare 6502 to 8085 in the gate count and die size derby. >believe the 650x core with only four internal software-accessible registers >(A,X,Y, SP) would have a substantially lower gate count than a Z80, which has >lots of register resources, (A,B,C,D,E,H,L,IX,IY,SP, plus a second set of the >same) and it does, but nowhere near the ratio that these registers suggest. Of >course there are several ways of looking at the definition of "gate" but it's Think of registers as memory bits... Z80 those number about 208 where 6502 has far fewer. However this is relative as a register can be one transistor and cap (dynamic) or a lot more for static. I believe the 6602 was a dynamic machine like many of the time. >odd that the ratio of gates consumed by each of these cores doesn't approach the >>2:1 that this estimate reflects. The production level pricing, basically a >cost based on silicon by the pound, seems to reflect this same ratio as do the >comparisons of the era when the 6502 was current. Whats not relected is the associated gating and silicon busses. Those eat logic and realestate as they are often less regular. >What would be interesting, since it's conspicuously absent from the list quoted >below, is the transistor count in the 6802 (a 6800 with internal clock >generator) and 6809. Yes, those should be there. Allison

24 years, 1 month

Allison: 2910c version of z80

by ajp166＠bellatlantic.net

From: John Ott <jott(a)hamming.ee.nd.edu> >I don't have your email address. So, do you still have the schematics >of your 2901C version of the z80? Have you done any stack based cpu's >with bit slice chips? (e.g. something to run native forth code on ) > >john I do still have them. No, I wont publish the notebook that contains the collected wisdom. I did this a lot of years ago. My $.02 2901 was an ok device but slow and turned out to the the speed limiter. Also the microcode for was a pain! Never did a stack cpu though the PDP-11 does that very well as is. Allison

24 years, 1 month

eBay alert: TI 980B mini and a HUGE IBM drive

by xds_sigma7＠hotmail.com

I dunno, I suppose that it's really Craig's perogative to do what he wishes, its his crud.. Old, yes, potentially interesting, yes, but above all; his. A good example would be a lot of the crud I've pitched because I didn't have the time to screw with it, or stuff I've picked up cheap because I expressed interest in it and the surplus guy said "you want it, then get it outta here today and I'll make it cheap". Besides, in my dealings with him I've never had any reason to dislike him, nor does your average a-hole rack up 667 positive feedbacks! Will J _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com

24 years, 1 month

PMC MicroMate

by azog＠azog.org

Got an interesting mail from a fellow who has a "PMC MicroMate" CP/M computer, and was wondering about it. The specs are neat - it's a fast Z80 (4MHz), but has 128k of RAM (so I guess it's CP/M-Plus, or a heavily modified version of 2.2), an internal 400k floppy and some sort of interface for three external drives. Am asking for details on the external drive interface. The machine doesn't sound familiar to me, but it sounds like a neat little thing - it's just a boxen, you need a TTY. --- azog at azog dot org Fools! You have no possible idea of what power you toy with! Release the pig!

24 years, 1 month

While we're on it, what's a Convex worth?

by xds_sigma7＠hotmail.com

What would the approximate value of a Convex Exemplar SPP-1000 be? 2 nodes (16 processors), 2GB of memory, a few gig of disk, most manuals and software, big n cool lookin'.. been offered one but don't know if the asking price ($5K) is worth it... Will J _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com

24 years, 1 month

How many transistors in the 6502 processor?

by ajp166＠bellatlantic.net

From: Iggy Drougge <optimus(a)canit.se> > >People always seem to forget the poor Dragon. Of course, it was essentially a >CoCo, or so they tell me. Both were the Moto app note for the 6809 and friends. >When was the 6809 released? Wasn't that about the same time as the 68000? Before the 68k. The 68k was late and moto needed something in between. Allison

24 years, 1 month

Looking for an IBM Portable Personal Computer

by vance＠ikickass.org

Anyone have one of these they could let go? Peace... Sridhar

24 years, 1 month

← Newer
1
...
54
55
56
57
58
59
60
...
65
Older →

Jump to page:

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

1999

1998

1997

test-drb May 2001