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
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
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
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
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
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
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!
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
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