Announcement

Collapse

Forum Rules and 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.


Rule 1: 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.


Rule 2: 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.



Rule 3: 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.


Rule 4: "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.

Rule 5: 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

HIMEMV2 or equivillent PROM

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

    #46
    Originally posted by Chuck(G) View Post
    Here's my question to the XT clone community at large.
    If you have a XT clone motherboard with 4 x 9 chip RAM organization that accepts 256Kb DRAMs in at least the first two ranks, do you also have a socketed 16-pin bipolar ROM on your board?
    I have just now examined five of my six clone XT motherboards (one is in storage). Only one of those five has the 4x9 RAM chip arrangement. 256Kbit chips in banks 0/1 and 64Kbit chips in banks 2/3. The motherboard is labeled "X'GOLDEN TURBO-BOARD".

    Close to the RAM banks is a socketed PAL16L8ACN. Near to the PAL16L8ACN is a "256K/640K" jumper, of which one pin is connected to pin 18 of the PAL16L8ACN. That pin is grounded for 640K and is pulled high for 256K.

    So, 20-pin, not 16-pin, and PAL, not PROM.

    Comment


      #47
      Useful info, thanks. Another clone i looked at--a 10MHz turbo board--uses 2 banks of 41256 and fills out the remainder with 4464 and 4164 (for parity). Obviously some vendors followed the IBM model and others didn't.
      Reach me: vcfblackhole _at_ protonmail dot com.

      Comment


        #48
        Out of 6 loose MBs two of mine are the same as Modem7's, i.e. 18x256 + 18x64 with a 20-pin PAL (U103) at the end of the ROM row and a 256/640 jumper, although one PAL is a 14L4CN while the other is a 16L8ANC (which is maybe also what Modem7 meant).

        I'm pretty sure I've got a few more in cases, including IIRC at least one 1024K version; I'll have a look if I get a chance.

        So, do I gather from all this that if we put in one of these custom GALs we get usable UMBs on our XT clones, not just RAMdisk & print buffer memory?

        Re Chuck's latest post which crossed mine in cyberspace, the rest of my boards are the same as his, i.e. 18x256, 4x4x64 and 2x64, both 10MHz and 12MHz. Also, these boards only have one 28-pin spare ROM socket instead of six like the above-mentioned boards, presumably for a larger all-in-one BASIC ROM.
        Last edited by MikeS; December 12, 2011, 12:16 AM. Reason: Comment on Chuck's post

        Comment


          #49
          Originally posted by MikeS
          So, do I gather from all this that if we put in one of these custom GALs we get usable UMBs on our XT clones, not just RAMdisk & print buffer memory?
          Yup, with the UMB driver, you can load DOS high, along with drivers and TSRs. Pretty cool on a resource-limited system. EMM386 or HIMEM not required.
          Reach me: vcfblackhole _at_ protonmail dot com.

          Comment


            #50
            Originally posted by Chuck(G) View Post
            Yup, with the UMB driver, you can load DOS high, along with drivers and TSRs. Pretty cool on a resource-limited system. EMM386 or HIMEM not required.
            Pretty cool indeed; I don't really need one myself, but I wonder if with possibly a little rearrangement of the I/O pins one of these GALs would be a direct drop-in replacement for those boards with a 20-pin PAL?

            Comment


              #51
              Without the board on hand to trace out the circuitry or at least a schematic, it'd be pretty close to impossible for someone like me. But given one or the other, it'd be pretty straightforward, I'd think.
              Reach me: vcfblackhole _at_ protonmail dot com.

              Comment


                #52
                Originally posted by Chuck(G) View Post
                Without the board on hand to trace out the circuitry or at least a schematic, it'd be pretty close to impossible for someone like me. But given one or the other, it'd be pretty straightforward, I'd think.
                Pshaw! Nothing's impossible for you!

                Not much point though unless somebody's seriously interested as the OP was.

                Comment


                  #53
                  Originally posted by Chuck(G) View Post
                  Yup, with the UMB driver, you can load DOS high, along with drivers and TSRs. Pretty cool on a resource-limited system. EMM386 or HIMEM not required.
                  Minor Correction
                  Loading DOS high is not possible with this arrangement since there is no "HIGH" memory, only UMB. If I understand correctly, "HIGH memory" is the segment immediatly beyond 1 megabyte.

                  However, even with my setup, which incudes EGA and Hard Disk which both use portions of "Upper Memory", I am able to use one block of 128K of UMB. I can load dosdata, command.com, several device drivers, and TSR's in that 128K of UMB. My config.sys starts out as follows

                  device=c:\use!umbs\clearmem.sys d000 2000 (clearmem.sys Chuck(G)'s wonderful creation)
                  device=c:\use!umbs\use!umbs.sys
                  dos=umb
                  dosdata=umb
                  shell=c:\dos\command.com /h/e:512 c:\dos /p
                  devicehigh=c:\hotshot\fdd.sys
                  devicehigh=c:\dos\setver.exe
                  devicehigh=c:\dos\ega.sys

                  If I change the "dos=umb" to "dos=high,umb" most of the system kernal still loads in low memory, since there is no actual "HIGH" memory. However the "dosdata=umb" puts 17,800 bytes of the system kernal into UMB. And the "shell=command.com /h ..." puts all of command.com in UMB. Kind of inconsistent here, because one could interpret the /h as referring to "HIGH memory, but it actually refers to UMB, or "UPPER momory.

                  Check out the folowing This is the current memory configuration for my 5155. Note that I have 608,960 bytes of base memory free and there is still 91,184 bytes of "UPPER" memory available for more drivers and tsr's.

                  Comment


                    #54
                    Thanks for the correction. I'dve thought that DOS=UMB would result in most of DOS loading in UMB, but I guess not--it requires HMA and that isn't going to happen. Perhaps I should RTFM more...

                    Reach me: vcfblackhole _at_ protonmail dot com.

                    Comment


                      #55
                      agreed

                      Comment


                        #56
                        Hey Chuck(G), or anyone else with knowledge about these things;
                        I'd like to play around with GAL Programming. Do you think one of THESE would work? Do you know anything about the software that comes with it. Would it be compatible with the JEDEC and/or EQN file that you included in the U44V2M.ZIP‎? If you don't like this one, is there one you can recomend?

                        Comment


                          #57
                          The TOP853 is cheap, and will do 20-pin and some 24-pin GALs (but not PALCE nor PEEL), but if I had to do it all over again, I wouldn't buy it unless what I wanted to do was to program EPROMs and EEPROMs. I'd want something to handle a wider array of programmable logic. The G540 is nearly as inexpensive, but handles a slightly wider variety; the Wellon seems to carry the biggest bang, but is also the most expensive.

                          If you want to buy my TOP853, I can probably make you a good deal on it--and I'll go buy the Wellon.

                          But yes, the TOP853 was used to program your U44.
                          Reach me: vcfblackhole _at_ protonmail dot com.

                          Comment


                            #58
                            OK, Let me know what you want for it, and I'll see if my Wife will let me buy it!! Send me a PM when you come up with a number that makes sense. Remember, I still owe you a HUGE favor, so don't go to cheap!

                            Comment


                              #59
                              I was going to ask, but I think I can get one shipped from HK for the price of shipping alone from OR.

                              Comment


                                #60
                                Nah, it's not big--it'll fit easily into a small flat-rate Priority Mail box.
                                Reach me: vcfblackhole _at_ protonmail dot com.

                                Comment

                                Working...
                                X