Mike's PCjr Page

Well in another post I talked about the PC-SPRINT board I found in a drawer of old parts..
what I realize now is this was meant for a PCXT type machine and NOT the PCJR...
as the plug in pins are in the wrong place to plug into the MotherBoard socket , the Disktray leg is in the way...
SO I thought the board had been assembled wrong, ( I did not know there was an XT version, THEN then JR came along)
so I swapped the U1 and U2 to allow it to properly fit...
well it seemed to work and does speed things up.
but I am convinced it is not right after going thru as much documentation and looking for pictures as I had..

I am relaying out the PC-SPRINT with SMT parts and to have some for the folks. but I want to get this right
so I need help with any docs you have or better yet pictures of a REAL PCJR model of the PC-Sprint board...
drop me a PM and I'll get back to you with my Email if you have any items that you think will help..

UPDATE;

I have reviewed the schems and data sheets and I am confident that my board is installed correctly, and that it was initially built with the U1 and U2 swapped.

So with that I will finish the PC-Sprint layout....

But I am still hoping someone will share some pictures of their PCJR PC-Sprint board, top and bottom and installed if possible...
I know its a pain....

lastly has anyone tried anything besides the 22.1Mhz crystal, D. Severson in his docs talked about trying over speeds, would like to know what if any results were gathered.


chuck

UPDATE:

I have the PCSPRINT board ready.
I need to have some boards built and tested....
but would like to know if we have an interest in this, it will decide how many I have made initially... probably 20 boards.

As a side note to the Addition of the PC-SPRINT board..

I set up a PCJr with standard 128K base system,
But had Alans JR-IDE board installed to boost the mem to 736K ( 640K recognized )
JRCONFIG setup for Video and memory
V20-10 chip installed
Tandy Video Mod on this unit

Ran Jim's TOPBENCH program and here are the results.. NOTE the SCORE !
( I think Jim can chime in and discuss exactly what this means in terms of system performance )

[UID44F2BE0]
MemoryTest=1537
OpcodeTest=5436
VidramTest=1532
MemEATest=1123
3DGameTest=856
Score=8
CPU=NEC V20-10
CPUspeed=7.16 MHz
BIOSinfo=1504037 COPR. IBM 1981,1983PS (06/01/83, rev. 0)
BIOSdate=19830601
BIOSCRC16=44F2
VideoSystem=CGA
VideoAdapter=IBM PCjr
Machine=PCjr
Description=PCJr V20-10, JR-IDE, PCSprint, Tandy Video Mode
Submitter=Chuck Terra

I am probably interested, depending on price. I do have a question though. Does this board have a way to switch back to 4.77mHz?

Yes in the picture you see there is a place for wires to:
TURN ON / OFF the SPEED ( SPD ) this signal is just grounded for HIGH SPEED, left unconnected it is normal Speed.
also is the connection for SYSTEM RESET button, something the JR lacks, so this is a nice addition..

COST: I'm not in the Sales business, so just doing this for the folks here..
I think the final price may be $20-$30 including shipping.... and I will build these up for you unless you enjoy a bag of parts...
One item I will most likely do is populate both 8284 parts as the original design asked the user to take the 8284 off the original MB and
put it in the socket U2 position.... I think just making a ready to go board is the best route...

Again the $ is estimated, I'm not looking to make any money, this is just having fun with the JR again and hoping to help others do the same..
but I can't imagine it will be more than $30.....

ps I have the 3 Floppy Board also that plugs into the original JR controller board and gives you three drive capability.
all cables are straight, same as the original on the 5.25 ( not supplied) but this makes it easy to set all your drives to DS1 Motor1.
Just a mention.... ( I am waiting on connectors for these and AkBkuku (aka SHELBY) is waiting to make a Youtube video on his Youtube channel.)

I've been preoccupied with stuff at home the past few weeks, but I look in and admire from a distance. Not just this thread either ... I've never seen the forums so active.

Anyway, I'd be interested in probably two kits for experimentation. Alan has been building the jrIDE kits on basically the same "cost" basis. We're a small enough group where I think that works out without anybody getting too burnt out. (Bigger projects like the XT-IDE have kind of been invaded by people with a profit motive, which makes me a little sad but it was inevitable.)

Completely agree, I'm just doing this to help keep the JR interesting to the folks...
I will most likely get 30-40 boards made, and it is usually around $150 for the batch...
so ~$6 board + ~$7 parts +$7 shipping USPS priority mailer
my labor is free of course...

I need to check schematics and then send them off usually takes 2-3 weeks....

At that price I would take at least 2 to start. May one or two later as I restore some of my PCjrs.

Put me down for one, please.

Mike