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IBM 5155 - "Insufficient memory to run"?

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  • Hugo Holden
    replied
    For my own 5155, (since I'm not very cluey about file transfers via the ports in DOS, though its easy with my SOL-20 with CP/M it seems with PCPUT & PCGET via the serial port) and I'm better with the hardware side of things than any software, I decided the easiest thing to do was to install a dual 3.5/5.25 floppy drive in one bay of my 5155, with the "Unique floppy controller board" and an vintage Seagate HDD in the other bay. My computer also has the AST 6 pack plus card and the smaller IBM isa memory card too to get 640kb.

    On the HDD I have DOS 3.3 and a number of other programs I use such as IBM's assembler and the usual DOS utilities and various other programs as there is plenty of space on the HDD. Also I put Windows V1.0 on it and Harvard Graphics. DOS 3.3 was the first version to support the 1.44Mb floppy. Also I have Procom for terminal emulation and Borland's Brief as a text editor to write assembly programs. So its all very handy having it right there on the HDD.

    But the convenient thing is I have an external 1.44 floppy drive on my other more modern computers so I can easily get files, programs & data etc in & out of the 5155 that way.

    There will be better ways to do it via the ports, but this hardware way "worked for me" and I have little trouble with it. The 5155 is not original though, but the two belt drive original IBM floppy drives might not have been wonderful either. I keep these with the computer & the original controller card, just in case one day I want to put it back to original. The power supply in the 5155 is up to running the HDD.

    It was an interesting process to fit the HDD, it requires a low & high level format and I had to try a couple before I found a good drive unit, but it has been reliable for a couple of years now.

    One thing I learnt the hard way was that the cheap external 1.44Mb USB floppy drives coming out of the far east are often really bad and corrupt files. I would advise buying something like a 1990's to 2005 vintage new old stock brand like IBM or Imation drive in its original box, cost more, but you won't have any troubles. I struggled for some weeks trying to work out why the programs I transferred via one of the cheap drives were corrupted. I only found it because I had jpeg images on a disk in the cheap 1.44 drive and noticed over time the pixels in the image were becoming corrupted, without that visual indication, I would probably still be working on it trying to find out what the heck was wrong.
    Last edited by Hugo Holden; April 6, 2020, 06:50 PM.

    Leave a comment:


  • Eudimorphodon
    replied
    Originally posted by ibmapc View Post
    I think I may have had that exact card in a 5150 back in the mists of time.

    Leave a comment:


  • ibmapc
    replied
    Originally posted by bvcderrttyyhjjjk View Post
    ..."Sixpak" doesn't really seem to be a thing that I can find on eBay around here at the moment. ...
    Try This Ebay Link

    Although, I still recommend the 640k Mod, This one is nice due to the inclusion of an RTC, a serial port and a parallel port. All useful on a 5155. And the seller includes a nice description and offers to provide tech help getting the thing working! Plus, he has 100% positive feedback! Shipping seems a bit steep though

    Leave a comment:


  • ibmapc
    replied
    Originally posted by Eudimorphodon View Post
    ...I'm sure there's other people on here that can speak more directly on the kinks, but if the instructions I found for it are accurate it's completely reversible and only involves plugging some chips into sockets, no soldering...
    Originally posted by Stone View Post
    Not entirely correct. A jumper has to be installed between pads 1 and 2 on jumper block E2.
    The jumper at E2 can be replaced with a wirewrap to a pair of pins on the bottom of the prom in socket U44.

    3. Remove the IC installed in the socket labeled U44.
    4. Install a jumper wire from pin 1 to pin 8 on U44. To avoid making any changes that cannot be removed later, the jumper can be wrapped directly onto the pins of the IC. Run this wire on the underside of the IC so that the wire is held in place. Reinstall the chip with the jumper in place. The IC may sit slightly higher in the socket, but make sure that it is seated properly.
    I wholeheartedly agree with the following;
    It counts as a "period correct" modification because the board was built to accommodate the larger chips and instructions for DIY memory expansion of IBM products aren't exactly a new thing.
    I have a 5155 that I've owned since bought brand new in 1985. My Dad and I did the 640K mod about two months after it was bought. We did the same mod on my Moms 5160. We did this mod based on instructions received at an IBM PC CLUB meeting in San Jose, CA!! So, many, many others were doing it. MUCH cheaper than memory expansion cards. I believe the chips required cost about 50 bucks at Fry's Electronics at the time.

    Leave a comment:


  • Stone
    replied
    Originally posted by Eudimorphodon View Post
    I'm sure there's other people on here that can speak more directly on the kinks, but if the instructions I found for it are accurate it's completely reversible and only involves plugging some chips into sockets, no soldering.
    Not entirely correct. A jumper has to be installed between pads 1 and 2 on jumper block E2.

    Leave a comment:


  • Eudimorphodon
    replied
    Originally posted by bvcderrttyyhjjjk View Post
    "Sixpak" doesn't really seem to be a thing that I can find on eBay around here at the moment. What would the difference and advantage/disadvantage to an original card in your experience?
    "Six Pack" was simply AST's name for a line of multifunction boards they sold that combined memory expansions with I/O ports, calendar chips, whatever. There were a lot of companies that made similar boards, I just don't remember the names for any off the top of my head. (And also on eBay such boards, especially from more generic manufacturers that aren't clearly marked, might not be listed as anything but "expansion card".) There's basically *no* disadvantage to one of these boards compared to the IBM board; memory is memory, and getting additional functions on a single card means you occupy fewer slots and, potentially, save a wee bit of power.

    Personally I think you might be making too big of a deal about the motherboard "modification". I'm sure there's other people on here that can speak more directly on the kinks, but if the instructions I found for it are accurate it's completely reversible and only involves plugging some chips into sockets, no soldering. It counts as a "period correct" modification because the board was built to accommodate the larger chips and instructions for DIY memory expansion of IBM products aren't exactly a new thing.

    Here is the no-brainer off-the-shelf modern solution if you want something you can just cash-and-carry. Clones of this board are sold on eBay, just be careful because some are designed better than others. The Lo-Tech one seems to have a pretty good reputation. With this board you can expand your 5155 up to 704k conventional *and* add some upper memory blocks useful for running DOS 5 and later with the right drivers.

    Leave a comment:


  • Stone
    replied
    Did you have a look at this?

    http://www.vcfed.org/forum/showthrea...936#post612936

    I have some available memory cards, e.g., 256k, 384k and a SixPak if any of those would be of interest.

    Leave a comment:


  • bvcderrttyyhjjjk
    replied
    Thank you all as always for your help.
    I've been retesting stuff and it seems like there is no real getting around the limited amount of memory.
    I got my facts mixed up on LapLink version, I apologise about that. Version 2 does work but does not support LPT cable transfer. Both versions 3 and 4 do support LPT transfers, but do not run on my 5155 due to insufficient memory.
    I'm considering going for more memory, because it is becoming apparent that even if I managed to find a way to make it work, it would be far more trouble than just getting a memory expansion in the first place.

    So, what are my options? (and also, should I continue discussing here or perhaps make a dedicated thread...?)
    My understanding is that there is: 1. A possibility to modify the motherboard to accept larger memory chips (I am not a big fan of this one because I'd like to keep the machine "period correct" and am afraid of damaging a perfectly functional specimen) 2. Finding an original memory expansion card (probably expensive, but I like this idea because it addresses my concerns with n.1) 3. Some other memory expansion (I noticed a few mentions of SixPak cards). I am not very familiar with this option and advantages/disadvantages as opposed to n.2.

    Any knowledge about the topic is appreciated at this point, as I'm trying to figure out what to do and am currently bored in quarantine at home due to the virus stuff going on, and the disassembled 5155 is taunting me every time I look at it LOL.

    Some eBay searching, for example, yielded a memory card listed as pulled from a working working IBM PC (64-256KB Memory expansion card), which looks to be what would have been in a computer like mine. The guy is in my country, so shipping would be convenient, however he listed the card for 100$. What do you reckon? Is this a reasonable asking price in your experience? Or should I try asking for a lower price/continue searching?

    "Sixpak" doesn't really seem to be a thing that I can find on eBay around here at the moment. What would the difference and advantage/disadvantage to an original card in your experience?

    Thank you as always for your insight and for helping me learn about this awesome stuff

    Leave a comment:


  • Trixter
    replied
    Originally posted by bvcderrttyyhjjjk View Post
    I don't understand the mismatch there.
    256K total, minus the space taken up by DOS, minus the space taken up by the program itself, is leaving only 117088 bytes for the program to use when it needs 140960.

    Most 5150s need 512K or 640K to be useful with the wide majority of software released 1. After roughly 1988 and 2. Will run on that class of machine. If you don't want to do a hardware mod, grab an AST Sixpack or some other memory expansion board.

    Leave a comment:


  • Stone
    replied
    Originally posted by bvcderrttyyhjjjk View Post
    That looks like it could be an interesting option. Unfortunately the Dropbox link in the thread is a 404 for me :/
    Try this:

    https://www.pcorner.com/list/network/unet.zip/INFO

    That's not UNET II, it's the earlier version. It only requires ~ 8Kb on the workstation.

    And, yes, LapLink III definitely works with a parallel cable.

    Leave a comment:


  • Eudimorphodon
    replied
    While I admire the sentiment in trying to keep it "original" sooner or later you'll probably want to upgrade the machine to 640k regardless. A lot of software that's period-correct for an XT requires more; if you're really going to stick to 256k I'd probably recommend running DOS 2.1 on it instead of 3.3, and of course that's going to limit your software choices even further.

    If the instructions here are correct the "640k" mod doesn't require any non-reversible changes to the motherboard, just plugging in a standard multiplexer IC, adding a jumper, and replacing the 64kbit chips in two of the RAM banks with 256kbit ones. I'm sure plenty of people did this back in the day. Alternatively if you want something you can back out just by yanking a card the well-known Lo-Tech 1MB SRAM board is a useful addition; not only can you use it to expand your base memory to 640k (or 704k!) you can use it to add some upper memory which can be used for a RAM disk or to run DOS 5 or higher with drivers and part of the OS loaded high.

    Obviously the other period-correct choice would be to add a vintage memory card. A good choice would be one of those multifunction cards like an AST Six Pack that in addition to adding RAM also gives you a serial port and a clock-calendar. Guessing at eBay prices you'd be paying through the nose for it, though.

    Leave a comment:


  • asmpgm
    replied
    LapLink 2 does not support parallel transfers but Laplink v3.00 does (I use it all the time on my 5155).
    The setting is on the Options screen under Communications Parameters, Transfer Mode.
    Since it is only 93,399 bytes, LL3 might run on your system.

    Leave a comment:


  • bvcderrttyyhjjjk
    replied
    I've been trying some different things.

    You could try running LapLink or Intersvr. Just might get lucky.
    I have tried running version 2 and 3 of LapLink, but they don't seem to support parallel ports. Version 4 does but... "Program too big to fit in memory"
    Intersvr is in DOS 6 if I am not mistaken; I have taken a look at it and it is way too large though. My drives are only capable of 360K, and DOS 6 requires FOUR 720k disks. I also wouldn't know how to split up the files to accomodate for the smaller disks...

    Keep in mind that the 640K mod is nearly invisible. The untrained eye would never see it.
    I know that, but I would feel like I was "cheating", if that's even a thing.

    These vintage projects can cost a fair amount, however, the cost is usually much less to purchase these obsolete items than they were in 1984!! If you stick with this hobby long enough, you'll have lot's of old bits and pieces around just because you might need them someday
    You are right, I guess I am just a bit spoiled because I do lots of building/fixing modern machines and finding parts is usually very easy and relatively cheap LOL

    You could use UNET II. It's a simple parallel Server/Workstation network with very little overhead.
    That looks like it could be an interesting option. Unfortunately the Dropbox link in the thread is a 404 for me :/

    Leave a comment:


  • Stone
    replied
    You could use UNET II. It's a simple parallel Server/Workstation network with very little overhead.

    http://www.vcfed.org/forum/showthrea...-based-network

    Leave a comment:


  • modem7
    replied
    I brought my IBM 5160 out of temporary storage. It has a 64-256KB type motherboard, with an AST SixPackPlus to take total convenional memory to 640 KB.

    With only 256 KB total enabled, and with no CONFIG.SYS and no AUTOEXEC.BAT, running SL.EXE of version 3.3 resulted in the same 'Insufficient memory to run' error message that the OP sees (excepting that the second bytes figure was slightly different).

    When I then enabled 320 KB total, SL.EXE started with no error.

    Leave a comment:

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