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IBM 5155 - "Insufficient memory to run"?

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Hello again,

I come to you with my latest IBM 5155 dilemma. Quick recap: got the thing for free, been trying to get it to "do things" like it would have in the old days without altering its original hardware. Managed to finally get it to work properly today and created DOS disks after LOTS of work.

Now, I wanted to have a way to send/receive data without having it disassembled and frankensteined with a bunch of adapters and a modern floppy drive hanging off the side.

I have found out about Fastlynx and got a demo version. I got the ls.exe file on the 5155, connected a Laplink parallel cable (no COM port unfortunately).

When I run ls.exe, however, I get this: "Insufficient memory to run. Need 140960 bytes of dynamic memory. Only 117088 bytes are available."

If I do chkdsk, however, it says: "262144 bytes total memory. 216960 bytes free." During POST it counts 256KB memory.

So what gives? Am I missing something here? How do I get it to run the program??

As always thank you in advance for your precious help.
 

ibmapc

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Many programs require more than 256K of RAM. Much more. Your best option would be to do the 640K mod. Or, you could buy an expansion card to increase RAM. But that would likely cost more and consume an expansion slot.
 

Ruud

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What DOS are you using? Don't forget that DOS needs RAM as well. And drivers, like a mouse driver, also need RAM. So start with nothing but a loaded COMMAND.COM and run MEM. That will tell you how much memory is available.
 
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Thanks for the replies.

Many programs require more than 256K of RAM. Much more. Your best option would be to do the 640K mod. Or, you could buy an expansion card to increase RAM. But that would likely cost more and consume an expansion slot.

I was worried about this. I am trying to keep it as "historically accurate" as possible, so in case I upgrade I would probably try to find a memory expansion card. This project is turning out to be quite the money pit... :?

What DOS are you using? Don't forget that DOS needs RAM as well. And drivers, like a mouse driver, also need RAM. So start with nothing but a loaded COMMAND.COM and run MEM. That will tell you how much memory is available.

I probably should have mentioned it, my bad. I am running DOS 3.30. I just tried starting as you suggested, but I get the exact same message, which I find very odd. I don't have MEM, I think that was added in a newer version of DOS (?). As I said though, when I ran CHKDSK instead it mentioned completely different memory numbers from what the error said. I don't understand the mismatch there.

:?
 

ibmapc

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I am trying to keep it as "historically accurate" as possible, so in case I upgrade I would probably try to find a memory expansion card.

Keep in mind that the 640K mod is nearly invisible. The untrained eye would never see it.

This project is turning out to be quite the money pit...

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;)
 

modem7

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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.
 
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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 :/
 

asmpgm

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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.
 

Eudimorphodon

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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.
 

Trixter

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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.
 
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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 :D
 

Eudimorphodon

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"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.
 

Stone

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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.
 

ibmapc

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...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.
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.
 

ibmapc

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..."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 :confused:
 
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