Announcement

Collapse

Forum etiquette

Our mission ...

This forum is part of our mission to promote the preservation of vintage computers through education and outreach. (In real life we also run events and have a museum.) We encourage you to join us, participate, share your knowledge, and enjoy.

This forum has been around in this format for over 15 years. These rules and guidelines help us maintain a healthy and active community, and we moderate the forum to keep things on track. Please familiarize yourself with these rules and guidelines.


Remain civil and respectful

There are several hundred people who actively participate here. People come from all different backgrounds and will have different ways of seeing things. You will not agree with everything you read here. Back-and-forth discussions are fine but do not cross the line into rude or disrespectful behavior.

Conduct yourself as you would at any other place where people come together in person to discuss their hobby. If you wouldn't say something to somebody in person, then you probably should not be writing it here.

This should be obvious but, just in case: profanity, threats, slurs against any group (sexual, racial, gender, etc.) will not be tolerated.


Stay close to the original topic being discussed
  • If you are starting a new thread choose a reasonable sub-forum to start your thread. (If you choose incorrectly don't worry, we can fix that.)
  • If you are responding to a thread, stay on topic - the original poster was trying to achieve something. You can always start a new thread instead of potentially "hijacking" an existing thread.



Contribute something meaningful

To put things in engineering terms, we value a high signal to noise ratio. Coming here should not be a waste of time.
  • This is not a chat room. If you are taking less than 30 seconds to make a post then you are probably doing something wrong. A post should be on topic, clear, and contribute something meaningful to the discussion. If people read your posts and feel that their time as been wasted, they will stop reading your posts. Worse yet, they will stop visiting and we'll lose their experience and contributions.
  • Do not bump threads.
  • Do not "necro-post" unless you are following up to a specific person on a specific thread. And even then, that person may have moved on. Just start a new thread for your related topic.
  • Use the Private Message system for posts that are targeted at a specific person.


"PM Sent!" messages (or, how to use the Private Message system)

This forum has a private message feature that we want people to use for messages that are not of general interest to other members.

In short, if you are going to reply to a thread and that reply is targeted to a specific individual and not of interest to anybody else (either now or in the future) then send a private message instead.

Here are some obvious examples of when you should not reply to a thread and use the PM system instead:
  • "PM Sent!": Do not tell the rest of us that you sent a PM ... the forum software will tell the other person that they have a PM waiting.
  • "How much is shipping to ....": This is a very specific and directed question that is not of interest to anybody else.


Why do we have this policy? Sending a "PM Sent!" type message basically wastes everybody else's time by making them having to scroll past a post in a thread that looks to be updated, when the update is not meaningful. And the person you are sending the PM to will be notified by the forum software that they have a message waiting for them. Look up at the top near the right edge where it says 'Notifications' ... if you have a PM waiting, it will tell you there.

Copyright and other legal issues

We are here to discuss vintage computing, so discussing software, books, and other intellectual property that is on-topic is fine. We don't want people using these forums to discuss or enable copyright violations or other things that are against the law; whether you agree with the law or not is irrelevant. Do not use our resources for something that is legally or morally questionable.

Our discussions here generally fall under "fair use." Telling people how to pirate a software title is an example of something that is not allowable here.


Reporting problematic posts

If you see spam, a wildly off-topic post, or something abusive or illegal please report the thread by clicking on the "Report Post" icon. (It looks like an exclamation point in a triangle and it is available under every post.) This send a notification to all of the moderators, so somebody will see it and deal with it.

If you are unsure you may consider sending a private message to a moderator instead.


New user moderation

New users are directly moderated so that we can weed spammers out early. This means that for your first 10 posts you will have some delay before they are seen. We understand this can be disruptive to the flow of conversation and we try to keep up with our new user moderation duties to avoid undue inconvenience. Please do not make duplicate posts, extra posts to bump your post count, or ask the moderators to expedite this process; 10 moderated posts will go by quickly.

New users also have a smaller personal message inbox limit and are rate limited when sending PMs to other users.


Other suggestions
  • Use Google, books, or other definitive sources. There is a lot of information out there.
  • Don't make people guess at what you are trying to say; we are not mind readers. Be clear and concise.
  • Spelling and grammar are not rated, but they do make a post easier to read.
See more
See less

Any interest in a PCjr CPU upgrade board?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • MicroCoreLabs
    replied
    If you recall you helped me run TOPBENCH on this a few years ago. The score of 11 is around the performance of a x286.

    Below is the entry in your latest database. Not sure why the submitter field is blank...

    [UID44F21E0]
    MemoryTest=1098
    OpcodeTest=607
    VidramTest=1818
    MemEATest=600
    3DGameTest=532
    Score=11
    CPU=MCL86 (FPGA)
    CPUspeed=100 MHz
    BIOSinfo=COPR. IBM 1981,1983 (06/01/83, rev. 0)
    BIOSdate=19830601
    BIOSCRC16=44F2
    VideoSystem=CGA
    VideoAdapter=IBM PCjr
    Machine=IBM PCjr (FPGA)
    Description=PCjr whose processor is replaced with an FPGA containing the MCL86 core that runs faster than the stock 8088 as well as an additional 128KB of on-FPGA memory that is accessed at the CPU core speed of 100Mhz.
    Submitter=
    Last edited by MicroCoreLabs; November 10, 2020, 12:08 PM.

    Leave a comment:


  • Trixter
    replied
    I'm biased, but Norton SI is hot garbage. You should try testing with TOPBENCH instead, which will give you more effective relative speed comparisons.

    Very interesting and exciting project Hopefully it can be adapted to non-PCjr 8088 systems as well, as a homebrew accelerator for those systems.

    Leave a comment:


  • MicroCoreLabs
    replied
    Hi,

    I have another update on the project: https://microcorelabs.wordpress.com/...-fastest-pcjr/

    When the board is running with the CPU in "unlocked" mode (not slowed to be cycle accurate) and using the fast SRAM controller, it appears to allow the PCjr to run 4X faster than an IBM PC/XT and as fast as an IBM PC/AT.

    There are a few PCjr related issues which I am trying to understand, but the MCL86jr board seems to work great! I don't have a lot of mileage on it yet, but the results so far look good.

    Some of the quirks are that Cartridge BASiC does not work, nor do some of the ctrl-alt-ins PCjr build-in tests. I also noticed that Norton's SI sometimes says it is an Intel 8088, and sometimes a NEC V20; so my initial guess is that there are loops in the software timing which rely on the exact PCjr hardware and CPU. Aside from this all of the other software I have tried works great. Things like King's Quest, Archon, Flight Simulator, multiple DOS versions, and more. I have more stuff to try, but so far most professional software seems to run fine.

    Currently I am entering "unlocked" mode as soon as a key is pressed (Im looking at an NMI), but need to add some snoop registers to enable/disable things like cycle accuracy and the fast SRAM controller. I will probably use write accesses to the BIOS ROM at F0000.

    I tried changing the computer-ID from 0xFD to 0xFF but DOS 3.2 doesn't like it! DOS 2.1 works fine and when running SI.EXE it shows up as an IBM PC. As soon as DOS 3.2 gets to the A> prompt and I press a key a bell sounds and the system locks up! I can make the computer-ID changeable under register contriol, but if some DOS's refuse to work then it might not be worth it...

    Thanks,
    -Ted

    Leave a comment:


  • ajacocks
    replied
    Very nice work. I am watching with interest.

    - Alex

    Leave a comment:


  • VERAULT
    replied
    Oh man i cant wait to buy one!!

    Leave a comment:


  • MicroCoreLabs
    replied
    Hi,

    I have an update on this project: https://microcorelabs.wordpress.com/...itial-results/

    Capture.JPG

    -Ted

    Leave a comment:


  • digger
    replied
    How about an Olivetti M24 or an AT&T 6300?

    Originally posted by Simplethings View Post
    Originally posted by MicroCoreLabs View Post
    > A 8086 version of this would be AMAZING.

    The MCL86 core's Execution Unit (EU) actually is an 8086; just like the real Intel device. It is only the Bus Interface Unit (BIU) that makes it an 8088 or 8086. So it can easily be ported to an 8086 design.

    What system did you have in mind?
    The PS/2 model 25. Other model 25 and 30 owners would probably really like this also. It would have to be like your dirst design probably to clear everything though: http://ibmmuseum.com/Planars/Model25...aYWeytO9TT2Gnk
    I would be very interested in trying such an upgrade on an Olivetti M24. Really curious to see what performance that old beast would be capable of with any CPU bottlenecks removed.

    Does this FPGA core also support the additional V20/V30 instructions, by the way?

    Leave a comment:


  • Simplethings
    replied
    PS/2 model 25 owners like me have to wait long periods of time for very rare CPU upgrades. I got a 33Mhz 386SX upgrade for my model 25/286 after two years of waiting for one to pop up - and it wasn't cheap. I think due to other bottlenecks in the system it will still feel "vintage", but for people with certain computers they really like this kind of thing is really cool.

    Leave a comment:


  • luckybob
    replied
    Originally posted by Trixter View Post
    As someone who thinks this project is cool, I cheer you on from the sidelines. However, I'm not sure I could pony up $200+ for a board.

    Is there anything that limits it to the PCjr? Asking because it might be interesting to see if your replacement could be made generic enough to replace any 4.77 MHz 8088 in any system.

    My sentiments exactly. And I don't even have a PCjr (yet).
    I feel cpu upgrades for old systems are AWESOME, but as my collection has grown to fill a 4-car garage, the ROI just isn't there for me. If I want to run something that benefits from a 286, I pull out my model 60 or 5170. And I own a good number of accelerator cards for these machines. (my model 80 is a 486/25 right now).

    I just feel 2020 hardware in a 1984(ish) machine just defeats the spirit of the machine. If I wanted to play pcjr games at 100fps, i'd just fire up an emulator. Its the reason I have the huge PEB box for my ti-99/4a and not that little credit card that does everything.

    That said, I want you to continue. I want to see this a finished project. I will be sad if this doesn't pan out.

    Leave a comment:


  • Eudimorphodon
    replied
    Originally posted by soviet9922 View Post
    if you can make this work in others 8088 computers i could go for it any day of the week .
    I suppose if it works on the JR it should work on a tandy ?.
    A Tandy 1000 runs its 8088 in max mode, not min mode, and the memory map is different, so presumably it would need some modifications.

    Leave a comment:


  • Simplethings
    replied
    The PS/2 model 25. Other model 25 and 30 owners would probably really like this also. It would have to be like your dirst design probably to clear everything though: http://ibmmuseum.com/Planars/Model25...aYWeytO9TT2Gnk

    Leave a comment:


  • MicroCoreLabs
    replied
    > A 8086 version of this would be AMAZING.

    The MCL86 core's Execution Unit (EU) actually is an 8086; just like the real Intel device. It is only the Bus Interface Unit (BIU) that makes it an 8088 or 8086. So it can easily be ported to an 8086 design.

    What system did you have in mind?

    Leave a comment:


  • Simplethings
    replied
    A 8086 version of this would be AMAZING.

    Leave a comment:


  • soviet9922
    replied
    if you can make this work in others 8088 computers i could go for it any day of the week .
    I suppose if it works on the JR it should work on a tandy ?.

    Leave a comment:


  • glitch
    replied
    Aries makes a series of coined (flat stamped) pin headers in a variety of sizes. I also recently purchased a full reel (50,000 pins) of Batten & Allen pins (the same ones Alan linked, I'd originally gotten my smaller quantity for Matt D'Asaro ). Henry Courbis (ReActive Micro also recently bought a reel of Batten & Allen pins, though his are bare copper with no plated finish, last time I talked to him he was potentially interested in supporting other hobbyist open source projects with his stock of them, too.

    Leave a comment:

Working...
X