Cracking Open the IBM PC Jr.
Summary: The PC Jr. was IBM's attempt to tap into the budding home personal computer market of 1983. While the PC Jr. had many positives with regard to the general home user, it also had several limitations that doomed it in the marketplace. I bought my PC Jr. in 1985 from my older brother who never quite figured out what to do with it. Feeling nostalgic, I decided to Crack Open the IBM PC Jr. to see what was actually in the case.
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These screws are a bit of a wild goose hunt. They only apply to the expansion card and they are double set screws. By that I mean, the first part of the holds the expansion card to the case and the second part holds the expansion card together. But we'll get to that later.
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Talkback
Jumper Wires
IBM PC Jr.
I don't know why, but I would love to get a PC Jr. case and put a new monster mother board and processor into it. Finding a power supply that would fit into the case might be a problem. The original Jr. power supply was actually built into the 110 volt electrical cord.
And I might have to also upgrade the 16 color monitor. It would be cool to be able to put a new technology video system into a PC Jr monitor case.
No, I'm not really crazy. I am just retired and bored.
Here is a modern solution
You will then have a modern computer that can run the
superior MacOS X or the malware sucking Windows.
RE: Jump the connection revisited (Cracking Open the IBM PC Jr.)
Windows IS malware.
RE: Jump the connection revisited (Cracking Open the IBM PC Jr.)
RE: Jump the connection revisited (Cracking Open the IBM PC Jr.)
Hi: I am Jud McCarthy, retired IBM engineer and manager. I am the president of the IBMSFQCCAA association. This is IBM?s 100th anniversary and we, some IBM retiree volunteers, are looking at restoring some old IBM systems, including PC jr?s. Although we a not in a position to buy any units, we would be very interested in aquiring your PCjr to add to the local Boca Raton Historical Society. You can dake this donation off of your income tax. Let me know your thoughts. Best regards ----- Jud
Justin (Jud) McCarthy
251 SW 9th Ave
Boca Raton, FL 33486
Home (561)391-1422 Cell: (561)504-7048
jhmccarthy@aol.com
RE: Jump the connection revisited (Cracking Open the IBM PC Jr.)
RE: Jump the connection revisited (Cracking Open the IBM PC Jr.)
IBM PC Jr.
The problem was that very little DOS based software was available at that time. If you wanted a program that wasn't available on the open market for the PC Jr., about the only simple way to get one was to write a program in Basic and run it on the Jr. I wrote a number of business programs in Basic on my PC Jr. system and they worked very well. A instruction book on writing Basic Programs came with the PC Jr.
BASIC built-in.. anyone remember S.I.M.P.L.E ?
even on the IBM's, I cant remember), if you did
not put a bootable floppy disk in, the PC would
default after a short period, and run BASIC from
the built-in ROMS.
So whilst (I agree) it's not the operating system
I can see why someone might get confused about
it.
S.I.M.P.L.E - was a joke out about the same time.
Single Input Multiple Programming *something* Environment
3 commands available... Start, Stop and Halt.
Regards,
Eli.
I would actually agree with the Author.
BIOS - Basic Input Output System
In the PC Jr, like most home systems of the time, you could
boot straight into BASIC and it provided access to all of
your features from graphics, timers, interrupts (through
sys calls and such), I/O (through peeks and pokes),
memory management with automatic garbage collection
and other features of the hardware/system.
Since the systems did not include a monolithic all encompassing Operating Systems, calling the ROM based
BASIC interpreters the OS is as correct as anything.
RE: Jump the connection revisited (Cracking Open the IBM PC Jr.)
Rob
RE: Jump the connection revisited (Cracking Open the IBM PC Jr.)
PEEKing and POKEing around in the memory addresses could probably have done some amazing things.
RE: Jumper Wires
They are often also used, besides repairing bad traces, as ECO (or Engineering Change Order) upgrades to correct design errors or errors that reveal themselves after the manufacturing of the circuit board is complete.
Back then, they didn't have a whole lot in the way of computer aided layout and thus was done by hand, so signal interference and a host of other problems wouldn't manifest themselves until after the board was made. Also, they could have just forgotten a connection prior to manufacture since they didn't have circuit simulators either. Or, they could have just run out of room on the layers for a trace, since they couldn't make them with as many layers as they can now.
Most of the logic chips shown on the controller, drive and motherboard are nothing more than basic and/or/not gates. You can google the numbers for their exact function if you have the whim.
RE: Jump the connection revisited (Cracking Open the IBM PC Jr.)
Or it they had bought their OS from Gary Kildall
one of the pioneers of the home personal computer???
Pioneers, Timex Sinclair, Adam, Heath Kit, Atari, Apple, and Commodore with both the Vic-20, and the C=64 out before the IBM PC-Jr. The PC, Jr was a tag along, Johnny-come-lately in this group.And considering its performance, it was grossly overpriced for the time.
Re: one of the pioneers of the home personal computer???
I had a VIC-20 and two C-64s and although the C-64 Executive came close to being classed as a "pc", the other two were designed as advanced "tv games" consoles, not personal computers. The other brands you mention weren't much better either.
I'm pretty sure that Commodore's PC-10, which was their first serious attempt at a home computer system, came out in response to the PC-JR, not before it. I also owned a PC-10 (but not a JR thank god)! And I am also fairly sure that Apple had not yet launched the Mac at that time, so you'd have to be saying the IIe was a "pc", which I'd argue it was not.
Of course it must be said that my experience was here in Australia, and it may have been different in the US of A.
So, from the viewpoint of a walking part of PC history, the PC-JR was a bit of a landmark - almost as "must have" as an iPhone today - a fashion accessory for wannabe techno-geeks.
They walked out the door under their own steam for the first few weeks - we couldn't keep up with demand. But they were also a piece of crap that my employer at the time, Computerland, sold off in huge warehouse sales for months after, trying to get rid of its JR stockpiles.
So there...
I would disagree...
PC - Personal Computer and has almost alway referred to
IBM compatibles. It simply did not apply to the host of
other systems. Ever.
Home computers.
[i]I'm pretty sure that Commodore's PC-10, which was
their first serious attempt at a home computer system,
came out in response to the PC-JR, not before it.[/i]
The VIC-20 and C-64 were both SERIOUS successes (not
just attempts) of home computer systems. While the VIC-
20 was little more than a game system, I know 100's of
people that got their first taste of programming with them.
The C-64 was used for a host of applications from games,
word processing, accounting, spread-sheets and dozens of
other "serious" applications. Before that, you had the CBM
and PET systems (like the 4032/8032 [quite cool serious business machine) that predated the IBM-PC by a few
years.
Tandy had a serious system with the TRS-80. Apple with
their II+. While these were NOT PC's they were home
computers and had great success for their time.
performance vs price
It was basically an electronic typewriter if you did not know a lot about computers - and who did.
I managed to borrow a friend's Amstrad that was just a solid (heavy lifting) block keyboard with a raised square block on the right that took a floppy disk housed in a cassette. It connected to a B&W small TV monitor I think. It was easy to pick up basic and do some some programming. Had DOS but mainly CPM .. something. Was writing a screenplay with 'Tasword'.
Do you remember the Compaq keyboards made in Ireland? Solid metal meant to withstand being picked up and dumped by twisters- :-)
I see that the IBM PCjr was made in America and although probably had an dipped etched circuit board, were all the resistors and capacitors hand soldered on, or by machines? There are a lot of parts ... manufacturing at the time probably couldn't get the cost down for widespread acceptance.
Be good to put original retail price (US OK) for the 'cracking open section' plus manufacturing methods at the time - for future generation use.