28 May
1999
28 May
'99
3:37 a.m.
-----Original Message-----
From: Don Maslin [SMTP:donm@cts.com]
Sent: Thursday, May 27, 1999 6:47 PM
To: Discussion re-collecting of classic computers
Subject: RE: What's a "computer console" selectric called?
On Thu, 27 May 1999, Arlen Michaels wrote:
<snip>
Actually, the
biggest challenge in interfacing this thing to a computer
was
to sort out how to read one particular status
signal from one of the
microswitch contacts in the print mechanism, so your computer could
start
sending the next character at just the right
moment before the
mechanical
cycle completely finished. Else your software
had to pause a few
Didn't you also have to feed it EBCDIC instead of ASCII in order for it to
'understand' what you wanted printed?
- don
28 May
28 May
11:57 a.m.
On Fri, 28 May 1999, Arlen Michaels wrote:
I don't think the Model 735 Selectric could even
handle EBCDIC directly. I
seem to recall the electrical interface was defined as tilt-and-rotate
signal names. My Selectric terminal certainly didn't do any translation by
itself from character-codes to solenoid signals, at least not from ASCII. I
had to do translation myself before sending to the printer. One way would
have been with hardware between the computer and the Selectric, eg- using an
eprom to translate each ASCII code into the correct combination of Selectric
tilt-and-rotate signals. My lazier way was to simply put a look-up table in
my driver code, to intercept each ASCII character enroute to the printer and
translate it into the appropriate pattern of solenoid signals first.
Well, considering the print speed capability of the Selectric mechanism,
your approach was unlikely to slow down the output.
Imagine if you had to drive a dot-matrix print head
with raw pin-driver
signals instead of the printer hardware figuring it out for you : same kind
of problem.
Seems to me that I recall just that approach in some of the early attempts
at printer graphics with CP/M.
- don
Some vendors did indeed supply an interface that took
ASCII from the
computer and sent the necessary tilt-and-rotate signals out to the
Selectric.
Arlen
--
Arlen Michaels amichael(a)nortelnetworks.com
Nortel Networks, Ottawa, Canada
12:34 p.m.
At 04:57 PM 5/28/99 -0700, don wrote:
Or in the case of some software I wrote WBW...
When some of the first letter-quality (daisy wheel and thimble) printers
came out, we quickly found that you could micro-step the print carriage and
platen.
Now, how many '.' fingers on the print wheels do you think we wore out once
we started teaching these printers to be plotters?!
-jim
---
jimw(a)computergarage.org
The Computer Garage - http://www.computergarage.org
Computer Garage Fax - (503) 646-0174
On Fri, 28 May 1999, Arlen Michaels wrote:
> Imagine if you had to drive a dot-matrix print head with raw pin-driver
> signals instead of the printer hardware figuring it out for you : same
kind
of problem.
Seems to me that I recall just that approach in some of the early attempts
at printer graphics with CP/M. 
12:46 p.m.
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12:19 p.m.
In message <m10nXGL-000IyHC@p850ug1>, Tony Duell writes:
A couple of other data points are worth pointing out here. The
NeXT printer worked this way. Since the display was driven by
translating Display PostScript into a raster pixmap, translating
it to a raster for the printer fit nicely into the model. Sun
also did the raster interface thing with the first SPARCPrinter
(though it's not quite classic by the 10 year rule AFAIK.) These
two are also the only two I can think of off the top of my head
that operate at 400dpi. The default behavior for the SPARCPrinter
was 300dpi, but you could put it into a 400dpi mode. In fact
I had to return a replacement unit becaue it worked fine at 300
but had an amusing wavey right margin at 400dpi.
Brian L. Stuart
At 04:57 PM 5/28/99 -0700, don wrote:
As an aside, there have been laser printer interfaces where the host
computer gets to control the laser engine control signals directly,
rather than talking to a 'formatter board' that turns
text/graphics/postscript/whatever into a suitable bitmap for printing.
Of course this is a slightly higher level than talking to the mechanics
directly, since you have a signal to tell the printer to start a page
rather than having to control the motor and clutches directly. But still,
the host computer has to monitor the Beam Detect signal and send suitably
timed pixels to the laser control input.
The standard PERQ laser printer interface was like this, and I've seen
similar interface cards for PCs, Atari STs and Acorn Archimedes machines On Fri, 28 May 1999, Arlen Michaels wrote:
> Imagine if you had to drive a dot-matrix print head with raw pin-driver
> signals instead of the printer hardware figuring it out for you : same
kind
>> of problem. 
1:23 p.m.
Tony Duell wrote:
As an aside, there have been laser printer interfaces
where the host
computer gets to control the laser engine control signals directly,
rather than talking to a 'formatter board' that turns
text/graphics/postscript/whatever into a suitable bitmap for printing.
[...]
The standard PERQ laser printer interface was like
this, and I've seen
similar interface cards for PCs, Atari STs and Acorn Archimedes machines
I think the Amstrad PCW printer works the same way. I can't check the FAQ
right now, but IIRC one item says, "How can I connect my Amstrad printer to
another machine? How can I connect another printer to the Amstrad?"
(Answer: Basically, you can't.) I don't remember if that printer is a
laser, inket, or matrix printer.
I've seen (and probably still have somewhere)
plastic daisywheels with a
metal pin for the '.' , just to make the last a little longer when used
like this.
Were there a couple of other commonly-reinforced pins, like 'e'?
-- Derek
1:37 p.m.
On Fri, 28 May 1999, Derek Peschel wrote:
I think the Amstrad PCW printer works the same way. I
can't check the FAQ
right now, but IIRC one item says, "How can I connect my Amstrad printer to
another machine? How can I connect another printer to the Amstrad?"
(Answer: Basically, you can't.) I don't remember if that printer is a
laser, inket, or matrix printer.
Its a dot matrix variety.
Sellam Alternate e-mail: dastar(a)siconic.com
------------------------------------------------------------------------------
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[Last web site update: 04/03/99]
2:56 p.m.
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4:19 p.m.
On Fri, 28 May 1999, Derek Peschel wrote:
Tony Duell wrote:
Dot matrix.
- don
As an aside, there have been laser printer
interfaces where the host
computer gets to control the laser engine control signals directly,
rather than talking to a 'formatter board' that turns
text/graphics/postscript/whatever into a suitable bitmap for printing.
[...]
The standard PERQ laser printer interface was
like this, and I've seen
similar interface cards for PCs, Atari STs and Acorn Archimedes machines
I think the Amstrad PCW printer works the same way. I can't check the FAQ
right now, but IIRC one item says, "How can I connect my Amstrad printer to
another machine? How can I connect another printer to the Amstrad?"
(Answer: Basically, you can't.) I don't remember if that printer is a
laser, inket, or matrix printer. I've seen
(and probably still have somewhere) plastic daisywheels with a
metal pin for the '.' , just to make the last a little longer when used
like this.
Were there a couple of other commonly-reinforced pins, like 'e'?
-- Derek
4:16 p.m.
On Fri, 28 May 1999, James Willing wrote:
Probably went from '.' to '*' to '#' to ' '!
- don
Seems to me
that I recall just that approach in some of the early attempts
at printer graphics with CP/M.
Or in the case of some software I wrote WBW...
When some of the first letter-quality (daisy wheel and thimble) printers
came out, we quickly found that you could micro-step the print carriage and
platen.
Now, how many '.' fingers on the print wheels do you think we wore out once
we started teaching these printers to be plotters?!
9657
days inactive
9657
days old
9 comments
7 participants
participants (7)
-
amichael＠nortelnetworks.com -
ard＠p850ug1.demon.co.uk -
blstuart＠bellsouth.net -
dastar＠ncal.verio.com -
donm＠cts.com -
dpeschel＠u.washington.edu -
jimw＠agora.rdrop.com