PCJr PC-Sprint / PCXT PC-Sprint

Hardware questions and modifications

Re: PCJr PC-Sprint / PCXT PC-Sprint

Postby ckreling » Sun Jul 21, 2019 5:40 pm

I'm in to purchase one. Thanks

Charles
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Re: PCJr PC-Sprint / PCXT PC-Sprint

Postby Chuckphd53 » Wed Jul 24, 2019 2:10 pm

I am getting some kits together now, will post in a day or so with some pics and price w shipping
(PCJR/JR-IDE-512DOM,TandyMod,V20-10Chip,BiDir,LPT2,3FlopBrd,
USBEmulator,ZIP100,PS2Keybrd,MouseSysMouse,InternalSwitcherPS)
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Re: PCJr PC-Sprint / PCXT PC-Sprint

Postby Chuckphd53 » Sat Jul 27, 2019 7:59 am

Boards are ready, see the new posting I made for these
(PCJR/JR-IDE-512DOM,TandyMod,V20-10Chip,BiDir,LPT2,3FlopBrd,
USBEmulator,ZIP100,PS2Keybrd,MouseSysMouse,InternalSwitcherPS)
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Re: PCJr PC-Sprint / PCXT PC-Sprint

Postby GHiero » Fri Aug 09, 2019 10:59 pm

I have installed a Chuckphd53 board into my PCjr., and it runs excellent for me.
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Re: PCJr PC-Sprint / PCXT PC-Sprint

Postby GHiero » Sat Aug 10, 2019 9:35 am

Topbench results with the PC-Sprint mod and NEC V20 @ 10MHz :

Score: 8
Memory: 1537
Effective addressing: 1122
Opcode exercise: 926
Vid adapter speed: 1451
3DGame distribution: 855
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Re: PCJr PC-Sprint / PCXT PC-Sprint

Postby Chuckphd53 » Sat Aug 10, 2019 10:17 am

I have used topbench and MIPS but sure would like the experts to interpret the results compared to
the out of the box PC Jr and give an indepth result perspective. :geek:
(PCJR/JR-IDE-512DOM,TandyMod,V20-10Chip,BiDir,LPT2,3FlopBrd,
USBEmulator,ZIP100,PS2Keybrd,MouseSysMouse,InternalSwitcherPS)
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Re: PCJr PC-Sprint / PCXT PC-Sprint

Postby Trixter » Sat Aug 10, 2019 11:30 am

The goal of these speedups for the PCjr is not necessarily to bridge over into a new class of software you can run, but rather to make existing 8088/PCjr-class software pleasant to use. With a topbench score of 8, you could look at it as 20% slower than a 6 MHz 80286, but I prefer to look at it as twice as fast as the IBM PC. So I'd consider it a good result.
You're all insane and trying to steal my magic bag!
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Re: PCJr PC-Sprint / PCXT PC-Sprint

Postby bagelswitch » Tue Aug 13, 2019 9:58 pm

Trixter wrote:The goal of these speedups for the PCjr is not necessarily to bridge over into a new class of software you can run, but rather to make existing 8088/PCjr-class software pleasant to use. With a topbench score of 8, you could look at it as 20% slower than a 6 MHz 80286, but I prefer to look at it as twice as fast as the IBM PC. So I'd consider it a good result.


Agreed. My personal target for a "Super Jr." was to get all the Sierra adventure games that could actually run on the Jr. in 16 colors (so, SQ through SQ3, KQ through KQ4, mainly) to an actually playable/enjoyable state. V20+sprint board+JrIDE meet that goal.
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Re: PCJr PC-Sprint / PCXT PC-Sprint

Postby ZiggyTheHamster » Thu Sep 12, 2019 7:20 pm

I've got this installed and I get video snow using the 8284 Chuckphd sent + the PCjr 8284. Others have mentioned that both chips need to be 8284A1s to operate in full speed without issues, so is this possibly the case here?
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Re: PCJr PC-Sprint / PCXT PC-Sprint

Postby bagelswitch » Thu Sep 26, 2019 9:50 pm

ZiggyTheHamster wrote:I've got this installed and I get video snow using the 8284 Chuckphd sent + the PCjr 8284. Others have mentioned that both chips need to be 8284A1s to operate in full speed without issues, so is this possibly the case here?


I'm using my own board design based on the original D. Severson schematic, not Chuck's fancier version, but I've never had issues of any kind at speeds of 8MHz or below with any combination of 8284A and 8284A-1 parts.

The 8284A-1 is absolutely necessary above 8MHz, but the only symptom I've seen of trying higher speeds with an 8284A is a system that won't boot - I've never seen video corruption from this mod.
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