PCJR Board by D. Severson ???

[Chuckphd53]

I found this board in an old Bin Drawer and it was (I think) a board for the PC JR, this was 10+ yrs back so I cannot remember but I think it was for SPEED Increase.
Pretty sure it is suppose to drop in the ZM8 chip position but I have not been able to find any docs for this MOD Board..
Any one seen this...... ( I bet Mike has )

If you have the info on this maybe Mike can post it on his pages with this picture...
I'd like to try it in a test JR I have .

thanks
Chuck

[Brutman]

It's PC Sprint .. I thought the docs were floating around somewhere; I believe Matt C. recreated it a few years ago.

Basically you replace the 8088 with a faster rated chip and run it at 2x the clock speed of the rest of the system. The other 8284 splits the clock for the new CPU.

I'll get the docs posted sometime this weekend. They have the original artwork. BTW, that's a nice artifact there ... I didn't realize he had boards made up other than for personal use.

[Chuckphd53]

As expected, thanks Mike..

if you need me to do a Schematic ( if there is not one available with the docs ) let me know and I'll get it done..

Looking forward to the Docs...

thanks
Chuck

[Chuckphd53]

just another thought, I am thinking of using the V20 -10 chip with this mod, 10Mhz should be a good test.

thoughts

[jscrow]

Matt sent me a PC Sprint board way back when. I still have it and still needs to be built. Anyway I have all the files, attached are the ones I think you're looking for. There are a bunch of other files including a few programs. If you want me to zip the folder and send to you, let me know...

*edit* updated the doc to the pdf version that is complete

[Chuckphd53]

this is good I can grab them
thanks

[Brutman]

I posted my version of the PC Sprint docs here: http://www.brutman.com/PCjr/downloads/p ... otated.zip

I haven't reviewed the docs in detail. I need the rainy season to start again before I have that kind of time ...

[Chuckphd53]

Thanks Mike,

I just made room in my home office to,work on my Jr again, actually found three binders with old Jr notes, from 2004, wow....

I will make the install of,the,PC Sprint and give a report.

Is there a bench mark speed test program that I might use to test before and after results...

chuck

[Chuckphd53]

well I installed the PC Sprint in a good system.... Nope ! did not work....

I reworked all the solder connections on the PC Sprint board , still nothing... system had blank screen did not even try to boot...
I guess the Crystal 22.11mhz is gone... I have one on order from Mouser...Will give it a go when I get them...

I did socket the 8284 chip and when I put the original chip back in the socket, the Jr booted fine and work ok..

between the TandyMod and PCSprint, ugh I'm batting 0 for 2...

Chuck

[Chuckphd53]

Ok.... UPDATED:

I have the PCSprint board installed and working..
Turns out that the U1 and U2 positions on the board were reversed...
if you look at the pictures posted earlier....it shows the Socket for the 8284 chip that you remove from the MB in the U1 position
this is WRONG the socket should have been in the U2 position
and the bottom plug in pins should have been in the U1 position..
I noticed this when I tried to plug in the board and it was hitting the Floppy drive holder plastic leg that goes thru the MB hole
and locks into the bottom of the case.
when I first installed the board I had the Floppy out and it was no in the way....

so all is good, it boots and the reset button works now...
I have not done any speed tests, I think there is a program MIPS out there somewhere that I will try to find and see if
it will measure the speed compared to that of stock JR...….
ps. My FUN COLOR system also has the V20 chip installed...

Chuck