I ran some service calls on Columbia pc's around 1987. As I was raised
in the Washington, DC suburbs (Silver Spring, Maryland) and had been
to Columbia, Maryland (which is located halfway between Washington and
Baltimore many times, I was surprised when reading the documentation
of the pc which stated it was made in Columbia, Maryland. Several
years later I needed to order a replacement motherboard and discovered
they had moved to Florida.
Marty
______________________________ Reply Separator
_________________________________
Subject: Re: Collectable PCs
Author: classiccmp(a)u.washington.edu at internet
Date: 11/9/98 4:10 PM
Innfogra(a)aol.com wrote:
>
> In a message dated 11/9/98 8:37:45 AM Pacific Standard Time,
> Marty(a)itgonline.com writes:
>
> << Does your Columbia list it as having been made in Columbia, Maryland?
> I believe their early pc's were made in Columbia, Maryland, later they
> moved to Florida.
> >>
> I will look. I didn't know that. Thanks for the info. i will let you know
when
> I find out.
> Paxton
I have 3 Columbia portable XT's.. Didn't know they were made in Florida.
Could be why there seem to be so many in the thrift stores down here in
Florida..
I have never been able to find anything on the internet about these
machines, looked everywhere and nothing found..
If anyone has any web sites with info on them, or knows some history on
them sure would like to hear from you...
Phil...
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From: Phil Clayton <handyman(a)sprintmail.com>
To: "Discussion re-collecting of classic computers"
<classiccmp(a)u.washington.edu>
Subject: Re: Collectable PCs
References: <a009459f.36475602(a)aol.com>
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< Ooh. I don't have anything from DDJ or Kilobaud. What issues?
I'd have to dig them out to get the dates. Likely around 1978-79.
< > I also have a copy of quest tiny Basic, hex dump, paper tape and it's
< > manual.
<
< How big is tiny BASIC? How did you communicate with it? A terminal
< over a 1854 UART?
It's 2k (fits in a 2716), romable and was sold that way as well. IO
in the version I have expects UT4 (monitor) or the equivelent. UT4 uses
EF4 and Q to do bit serial to tty.
Oh, I bought it because it was cheap ($10 in 1978) and never used it!
I was having more fun running small stuff in asm.
Allison
< It's all a matter of time, place and comparison. What was DEC charging
< for a box, OS and BASIC at the time?
An 8E with basic, enough core and tty would likely be about 14-18k maybe
less. Used it could be in the under $3000 range in '77.
In 1972 I was offered a pdp-8I with he works(TTY, RS08, DECTAPE, 32k core)
for a mere $10,000 operating! It was a bit steep for me but a new
chevy truck then was $3300.
< >Absolutely. I agree 100%. If he had priced it in the range that a
< >hobbyist could afford, and proportionate to the cost of the system ($50
< >for the kit?) then people would buy it. Its nothing to throw down $25
< >$50 if you're getting a manual and support with that.
<
< Pish-posh. In 1978, we're talking about a bunch of scroungy ex-
< or current- ham radio operators who'd cross the street to pick up
< two pennies on the sidewalk. Even today, why do people routinely
< pirate software that can be had for $20 in the CompUSA discount bin?
That characterization was at best inaccurate. The members of LICA (LI
computing ASSOC) were less than 25% hams, many(60%) were professionals in
the industry (mostly large iron). Most were techs and hard wroking slobs
that the price of a KIM-1 was stiff for them and $350 for Basic was
several weeks pay.
Allison
< I have broken out the box box 'o 1802 stuff. In it are:
I don't have the VIP but I have the manuals for one. I also have the
articles from Popular Electronics, DDJ and Kilobaud.
I also have the basic DOCS for the 1802.
COS/MOS Memories, Microprocessors, and support systems 1979. This
includes data and schematics for the CDP18S6xx series modules.
MPM201 User manual for the RCA CDP1802 CPSMAC Microprocessor.
MPM203 Evaluation kit manual for the RCA CDP1802 COSMAC Microprocessor
(1976)
MPM206 Binary Aritmetic subroutines for RCA cosmac Microprocessors
I also have a copy of quest tiny Basic, hex dump, paper tape and it's
manual.
Allison
> < I have broken out the box box 'o 1802 stuff. In it are:
> I also have the basic DOCS for the 1802.
The 1802 data sheets are still available from Harris.
New, and PDFied. Also for most of the pheripheral parts.
> MPM206 Binary Aritmetic subroutines for RCA cosmac Microprocessors
> I also have a copy of quest tiny Basic, hex dump, paper tape and it's
> manual.
These two ar e very interesting.
Servus
Hans
--
Ich denke, also bin ich, also gut
HRK
> On Tue, 10 Nov 1998, Doug Yowza wrote:
> In 1970 a college art prof told me that "multimedia" is 2 or more Koda
> Carousel projectors plus a sound track. In response to questions he d
> insist that no substitutions were permitted.
How pandatic of him. When I was in school a few years before that
multimedia was sound, pictures in the form of Video, Still pictures,
moving pictures, lights and maybe action! The concept of the time was
hit as many senses as was possible.
Allison
< Absolutely. I agree 100%. If he had priced it in the range that a
< hobbyist could afford, and proportionate to the cost of the system ($500
< for the kit?) then people would buy it. Its nothing to throw down $25 o
< $50 if you're getting a manual and support with that.
The KIT was $500, but that only got you the box and a CPU. Ram was
expensive then and the IO was either serial, tape, or parallel so you
also needed a TTY or CRT(I used CT1024). Still BASIC for MITS prices
was ok but as Billy's price it was out of reach.
FYI at the time of the article (early '75) a system with 32k of ram,
cassette and serial IO would be over $3500! The 8800 was cheap, but
not that cheap. Three years later (early 1978) that price would have
dropped to 1500 or less due to the lower cost of memory boards and the
lower cost of the system itself. The Disk system would be around late
'76 early 77 with software to lag behind it.
In 1977 you could get languages, for far less than $100 and many offered
features that MSbasic did not have. Examples of this were PT basic, Focal
and NS* disk BASIC. Also Tiny basic was published along with a little
later LLL8k Basic as examples of free software with sources available.
That trend nearly killed MS and did put a few others under. It was very
hard to make a buck on paper tape or cassette based software. Affordable
disk systems opened up the market and made it a serious force for applied
software.
Allison
< > < > for a intersil 6100 (12 bit pdp-8) based system.
< > <
<
< Do tell.
A small potload of them for the Intersil sampler, there was an article
in Microcomputing December 1979 (P54), also the intersil data books and
schematics for some of the board level porducts and app notes.
Also several megabytes of PDP-8 software and a DECMATEIII to run it on.
< That wasn't memory mapping. The 1861 DMA'ed the video data out.
No, that was how it transfered the data to the CRT (it would read memory
with DMA and serialize it add sync and all). the User would write data
to the memory map that was display memory to change the pattern on the
screen. That makes it memory mapped. the fact that it used DMA was a
simplification of the hardware.
< I saw one at the Computer Museum of America, but I don't think it is
< available.
There are still a bunch around. They only made maybe 20-30,000 of the
8E/8A series.
< Well... they _were_ nice and bright. Ah, the countless hours I spent
< staring at those ember-bright dots, counting toggle pulses in my head
< to fix a one-byte bug.
First thing I added was four more to latch the address.
< Ob1802Trivia - don't execute the one "missing" instruction, 0x68. ISTR
< that the CPU went berserk and whomped memory randomly.
Well, all of the 6Xh instructions manipulate the X register directly or
indirectly.
60 inc X R(X)+1->R(X) ! memory pointer pointed to by R(X) is
! incremented
What's significant is the operation is a dummy output but since having
the N lines with 000 on them was a nop all it does is increment the
pointer.
61->67 out M(R(X)) ->BUS; R(X)+1 -> R(X)
Effectively output a byte pointed to by R(X) to the device and increment
R(X). The N lines will have a value of 1->7 depending on opcode.
69->6F input BUS -> M(R(X)); BUS -> D
Now... the cosmac uses the high bit of the N register to signal internall
that the instruction is a input so....
68 inpGarbage BUS -> M(R(X)); BUS -> D
In this case bus content is undefined so you just trashed the accumulator
(D) and the memory pointed to by R(X).
On my system due to the pullups on the bus and all that meant a FFh was
loaded every time. Handy way to stuff a -1.
The COSMAC is a real simple machine and it's behavour is very predictable
with one general exception... The CMOS process in the late 70s had
horrendous propagation delays and the timing of the chip was very variable
with voltage. So at very fast clocks the timing on some signals could
have a negative setup at one voltage and a positive setup if the voltage
was higher. I know of few people that ever ran successfully at the rated
maximum. At moderate speeds it was easy to use.
Allison
< and deluging the market with bad software. The only problem is, everyon
< said "OK, Bill. Here's my checking account. Don't worry about fixing the
< kinda gives your software 'character'."
The early BASIC he did was buggy as hell too. The first version that
was semi OK for 8k basic was 3.51.
Allison
< At the time, MITS had an absolutely miserable 4K dynamic memory board.
< This was one of the few ways that they could entice folks to buy it.
The 88MCD was poor, the S4K slightly better and neither would work with
z80s without being severely hacked! I had three of each and they were
all junk. Why three of each... at one point S4Ks were offered less rams
to anyone that had 88MCDs at a ok price. I was able to make them
acceptably reliable by pulling the Drams and putting in compatable
static parts (NEC uPD410). The board layout still stank and the
general noise level on the bus didn't help. Up grading the bus to
a WAMCO or compupro with terminations helped. Replacing the whole
machine with a NS* Horizon was a vast step forward.
Allison