>It never ceases to amaze me that, when offered an opportunity to
celebrate in a positive manner, groups of people will choose to smash,
burn and destroy things instead. If it were some kind of demonstration
against a particular company for some kind of social violations, it
least
smashing a computer made by that company would have some kind of
symbolic
purpose (albeit still a negative one). But to just smash something for
the hell of it.
How odd, seems like a natural thing to do. Many's the time I'd like to
have taken the PC under my desk, loaded it into the trusty old trebuchet
and slung it across the countryside. As for wanton destruction, don't
knock it till you try it. Last month I had the opportunity to fire a
75mm cannon at some cars, wasted a really nice Subaru. Then I got to
watch as the rest of the cars were strafed by a .50 Browning from a
helicopter. It's a great feeling to watch a Lincoln being blown apart.
We surely do live in the best of times.
Jack Peacock
< Well I'm not really a Qbus person. I never got into PDP-11s much and apa
< from adding and removing boards from a uVAX-II didn't get to play with Q
< much. The sort of thing I'm looking at is a little more sophisticated th
< "a bus is something that connects cards together" but a little less bori
< than a dry description of arcane features of signal timing and decay
< (although I've read plenty of these in my time).
let's see if I can do a little on this.
Q-bus DECs compaction of Unibus. Qbus is a time multiplexed, asychronous,
16bit data and depending on age of the system 16, 18 or 22 bit address.
It has termination and controlled loading to allow operation at high spped
using open collector drivers. While a 16 bit bus it also supports various
byte transfers. Q-bus is compact and fairly sparce in signals but supports
memory, device, interrupt and DMA transfers using the bus data lines and a
set of 10 control signals. There are other signals present for processor
control such as RUN, PowerOK and Binit are examples. There are more pins
than actual signals, some are redundant power for example. There are
lines for bus mastering, DMA and interrupt grant/ack are examples.
Most devices fall into several loose catagories, IO and memory.
The lower 16bits are multiplexed on the bus before every transaction using
the same lines data will be transferred on. Cards use BSYNC to capture
address and start any bus cycle that pertains to them.
Memory is fairly straight forward in that its timed off bsync and will
use the other 9 signals to synchronize it's operation. Transactions will
be read (word/byte) or write (word/byte). One of the characteristices
of PDP-11s is they always read before write (a read modify write cycle
is the normal thing). IO devices are identical to memory and by
convention and use of BBS7 are located in the top page of the 32KW
address space (1 11x xxx xxx xxx xxx).
The remaining transacions of not are interrupts and DMA. Interrupts are
posted via a request line that can be superceeded by another board
physically (buswise) closer to the CPU and will be granted by the CPU
to the higest(closest) requestor then and acceeding requesting modules.
When an interrupt is granted the board will place a byte(7 bits lowest set
to 0) VECTOR on the data bus that the processor will use as a pointer
to a table in the first 512byts of ram (interrupts vector table PSW and
interrupts service address is located in two words). DMA also has a grant
acknowledge and positional priority. Once granted DMA may proceed with
byte or word transfers of any length, though generally restricted to short
bursts to avoid hogging the bus.
The basic signals are:
BDAL 0->15-L -L denotes active low signal
BSYNC-L
BBS7-L Predecoded bank 7 signal (IO bank)
BAIKO-L Bus interrupt acknowledge
BWTBT-L Bus Write Byte
BRPLY-L Bus Cycle reply (must be supplied to continue the cycle
or a bus time out error occurs)
BDIN-L Bus Data IN toward CPU
BDOUT-L Bus Data OUT -> to module
Bus cycles have a distinct protocal (sequence) and timings.
< Does this narrow it down a little? I'm sort of surprised that there isn'
< nice description on the web somewhere....
Me too, though trivial it's not. I tried to avoid a description of each
line as that is quite lengthly.
Allison
At 04:48 PM 8/24/98 -0500, you wrote:
>
>< SMS300-1
>< 0002624
>< 001 A 7620 on it
>
>An early bipolar processor (very strange) that was often used for signal
>processing or stuff like hard disk controllers.
>
>Allison
>
Oh, you mean like a National 8X300?
Westen digital used 8X300's for awhile on disk controllers.
Alot of PC <-> Mainframe adaptors used 'em too . . .
Jeff
In a message dated 98-08-24 19:01:57 EDT, you write:
<< Here's a question: what _obsolete_ computer would you choose for this
miracle machine, assuming you have unlimited power? >>
how about any of the IBM family one series? there's plenty of them and no
shortage of them except for the 5155 and 5140 maybe. i'd keep those.
david
Plus consider that you could then ask for the smashed machines and
restore them. THere is unlikely to be any serious damage except
drives and CRTs. You could certainly scrounge the chips.
>> I think we should massively e-mail their chamber of commerce about
the
>> enormous stupidity of that event, this is an event supposed to
celebrate
>> technology not destroy it!
>
>If it is an XT, VAX, C64, Amiga, or whatever - I think humanity could
>spare one for a bit of fun.
>
>William Donzelli
>william(a)ans.net
>
>
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< sent us a cardboard baffle to try to get it to work but the only real
< solution for us was to use a different brand of 8" drive. Did anyone
< ever have a good experience with Calcomp floppy drives?
DEC used the mechanics and heads for the RX01 and RX02 disks with good
results. The electronics however were DEC built.
< This was pre-CP/M days, we used the floppy as a sort of fast paper tape
< replacement, keeping a manual directory of tracks which held code. I
< patched in a crude driver to the ALS-8 assembler development ROM system
< from Processor Tech to read/write memory blocks onto the floppy.
It's needs for a seperate CPU and a NEC D372 controller is familiar.
The grandfather to the design was used as a proto for a NEC TECH note
which I have. I used a version that for a NEC (NOT S100) PDA80
development system and it worked ok with good drives.
Allison
RE: the discussion on converting the Sun Remarketing Mac XL back to a Lisa
2 - I called Sun Remarketing and spoke with their most knowledgable Lisa
person (thanks Marion!) who was less than encouraging about the project.
According to him, it is not just replacing a few ROMs and PALs, and removing
a transformer from the CRT yoke - it requires replacing the main logic board
>from an original Lisa, and unless you have a wrecked Lisa, that item may be
a little hard to find. On the other hand, this group always seems to have
someone who, not knowing a task was impossible, did it anyway! I you're out
there and have "done it" - please make yourself known!
Bob Stek
bobstek(a)ix.netcom.com
Saver of lost SOLs
>Two, not one, two Imsai's with Imsai disk units up for auction on ebay.
Imsai disk unit as in the original 8" Calcomp floppy? Hmm, from '76?
Be careful if it is, those drives had an extremely short lifespan (we
experienced a 300% failure rate, every drive ordered failed, and
replacements failed too). Cooling on the first Imsai floppy cabinet was
completely inadequate for 8" drives, IMSAI later redesigned it. They
sent us a cardboard baffle to try to get it to work but the only real
solution for us was to use a different brand of 8" drive. Did anyone
ever have a good experience with Calcomp floppy drives?
The controller was pretty sophisticated for it's day, used a channel
type design, you sent it basic info and it read the data into memory.
This was pre-CP/M days, we used the floppy as a sort of fast paper tape
replacement, keeping a manual directory of tracks which held code. I
patched in a crude driver to the ALS-8 assembler development ROM system
>from Processor Tech to read/write memory blocks onto the floppy.
Jack Peacock
The 800XL (circa 1983) is a streamlined version of the Atari 800 (circa
1979). Although the 800XL has 64K RAM standard, while the 800 could only
support 48K, the 800 had an expansion bus that the 800XL lacks. The 800XL
is a 1.79 MHz 6502 machine with 24K ROM including BASIC. It accepts most of
the same peripherals as the 800, including software (mostly game)
cartridges. It has 2 joystick ports that accept 2600-style joysticks.
Floppy drives are available, which run Atari DOS. See
http://www.geocities.com/~compcloset/atari800XL.htm.
The Atari 520ST (circa 1985) is a 16 MHz Motorola 68000-based machine that
was created to compete against the Commodore Amiga (Atari almost acquired
Amiga Technologies before Commodore did, and was always jealous of that
fact). It indeed runs a GEM-based GUI and the TOS operating system. The
STf version has an internal floppy drive, and the STfm version has a floppy
drive and RF modulator. See
http://www.geocities.com/~compcloset/atari520stfm.htm.
Kai
-----Original Message-----
From: Max Eskin [mailto:maxeskin@hotmail.com]
Sent: Monday, August 24, 1998 11:46 AM
To: Discussion re-collecting of classic computers
Subject: Ataris
Today I saw an Atari 5?0ST and an 800XL. As I understand, the ST ran
GEM. Is this an interesting computer at all? What about the XL? Was
this one of the BASIC computers?
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< SMS300-1
< 0002624
< 001 A 7620 on it
An early bipolar processor (very strange) that was often used for signal
processing or stuff like hard disk controllers.
Allison
