(writeup and source code) Produced from 1984 to 1993. Memory sizes from 64K to 4Mb (64Mb possible) with an
8 bit Z80 micro. There was about 4000 sold, which I feel was pretty good for pre-internet days.
Cheers Don...
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Don McKenzie
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Offloading background print spooling from a microcomputer CPU, especially one running a non-multitasking OS.
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Roland Hutchinson
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Yes, we are talking about the days when a printer just had a micro, and no internal memory, or very little.
When you did a print, your computer stopped completely until the print had finished, as it was spending 100% of the time chatting to the printer micro. When the print finished, you got access to your computer again.
An in line printer buffer allowed you to dump the contents to the buffer fairly quickly, and the buffer then chatted to the printer, which enabled you to get on with your work on the computer.
That is the way things worked in the PC world in the 70s and 80s.
Cheers Don...
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**Indeed. Up until I could afford a '386 with 4MB RAM (which I could use as a print spooler), I used the mighty Dontronics buffer with my various dot matrix printers. That was how it was with DOS. It was pretty much impossible to do two things at once. All that changed with OS/2, which had a brilliant print spooler and put Windows 386 to shame. Pity IBM lacked the marketing nouse and printer support (bloody thing wouldn't work with my HP Laserjet!!) that Microsoft had back then.
I think IBM had (and still have) marketing nounce - it's just that they concentrate on a rather different market, instead of trying to get millions of people to spend a few hundred each they prefer to get thousands of people to spend a few million each.
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I spent a tidy sum for a daisywheel ("true letter quality") printer with a built-in print buffer--basically a Brother that a third-party company had rigged up and resold. About $800 in the early 80s--a couple of years after the IBM-PC came out, and it was _highly_ affordable compared to what the lowest daisywheel printer prices had been a year or two earlier (as in twice the price for a reconditioned, though admittedly heavier- duty one).
--
Roland Hutchinson
He calls himself "the Garden State's leading violist da gamba,"
... comparable to being ruler of an exceptionally small duchy.
--Newark (NJ) Star Ledger ( http://tinyurl.com/RolandIsNJ )
Oh, and I forgot to mention, the Brother printer was basically a Brother typewriter mechanism that they had lightly re-engineered into a printer. It worked perfectly for years; I eventually gave it away after I got a laser printer.
--
Roland Hutchinson
He calls himself "the Garden State's leading violist da gamba,"
... comparable to being ruler of an exceptionally small duchy.
--Newark (NJ) Star Ledger ( http://tinyurl.com/RolandIsNJ )
it allowed you to buffer printer data, so you could use the PC for something else. This would have been in the days of DOS when there was no multitasking.
One example would be that I can clearly remember a colleague who was frequently printing out something like cad, schematic, PDF or similar files in 1991 on some sort of laser or very high quality printer. He used a surplus XT computer (which ran about 4-8 MHZ) to buffer the print file, send it to the printer etc.
To process and print these files took some 4 hours to do, and this way the second PC (XT) could handle it all, leaving the main PC free to perform other tasks.
I don't remember how much memory the XT machine had back then, but Im fairly sure it was 640k (0.64MB).
The Dontronics printer buffer was a lifesaver in that it would connect between the printer port on the PC and the printer, rapidly (by the standards of back then) collect the data from the printer port by "pretending" to be a printer, store this data it in its internal RAM then slowly feed it out to the printer as the printer requested it. It was also affordable to the average tech minded hobbyist of the time at around $100 for the kit IIRC, where a second PC would be out of the question as to affordability.
As printers back then also didnt have much (if any) in the way of ram, and printed much more slowly than now, this meant that the print job could proceed directly from the printer buffer without the PC being held up performing this task. Nowadays printers have substantial ram and Windows/Linux etc contain sufficient memory and processor speed to handle all this in the background.
For example a dot matrix printer (most common type in use) could take
5-10 seconds to print a line of text, if you had many pages to print, your program could be sitting tied up doing this function for a significant time (and you couldn't use the machine) if you had to print out a report of many pages without the printer buffer.
(It would be like now if you were printing a high res image onto A4 photo paper at the highest resolution and quality and the PC was "locked" during this whole process for several minutes.)
Daisy wheel ones were probably faster, but limited to alphanumeric characters only (like mechanical typewriters). None of this gear was in any way cheap to buy.
It is a very different world now.
I think our PBUFF had around 1mb in it. It used computer ram sticks, of a type you don't see anymore, they had pins on them, like a very long single sided DIP package, but it was a PCB with RAM IC's on it. (much like now). SIMM or DIMM (Cant remember).
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Sounds like SIMMs (DIMMs are current tech). Somewhere I have a bunch of smaller (256K) SIMMs from an old Mac. I used one as a keychain till the ICs fell off; I plan to use the others after getting them coated in Lucite or something similar. -- Joe
At times, we used the same memory as the XT PC of the day, which was 30 pad SIMM Modules:
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We sometimes soldered pins onto them, so we could insert them into a 30 pin socket:
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Or simply plug them straight into a suitable socket:
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However most users simply plugged DIP version DRAMs straight into the PBUFF board, which was designed to accept them.
The SIMMs were just a later alternative to use old XT DRAMs, and-or to build up the memory capacity of the original buffer board.
DRAM could be 1, 2, 4, or 8 DIP chips, or 30 pin Simm modules. I think I had 11 memory sizes. So by using a combination of DIPs and-or SIMMs, you could use your surplus memory chips for somethig useful.
Cheers Don...
=================
--
Don McKenzie
Site Map: http://www.dontronics.com/sitemap
E-Mail Contact Page: http://www.dontronics.com/email
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No More Damn Spam: http://www.dontronics.com/spam
USB Isolator 1000VDC For Protecting Your PC OR Laptop
http://www.dontronics-shop.com/usb-iso-low-full-speed-usb-isolator.html
These products will reduce in price by 5% every month:
http://www.dontronics-shop.com/minus-5-every-month.html
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