full 640 KB memory on IBM 5150 unnecessary?

[Retro Canada]

I had to use a 20Mhz clock because 22.11Mhz was too overclocked for my slow DRAM chips...

Here is my original post. That time I used a 17.4 Mhz:

http://www.vcfed.org/forum/showthread.php?60803-I-overclocked-my-IBM-5150&highlight=PC+SPRINT

But now it shows 1.5x the PC-XT speed.

 

[vwestlife]

like original Wordstar IIRC it didn't work with too much ram

That's because the old WordStar code was a total mess and they only did the minimum changes necessary to convert it from 8-bit CP/M to 16-bit MS-DOS. As a result it only used a maximum of 64K of RAM and didn't support subdirectories. They had to give up on it and totally rewrite the code from scratch.

GW-BASIC / BASICA also only used 64K of RAM no matter how much you had installed.

 

[Chuck(G)]

That's because the old WordStar code was a total mess and they only did the minimum changes necessary to convert it from 8-bit CP/M to 16-bit MS-DOS. As a result it only used a maximum of 64K of RAM and didn't support subdirectories. They had to give up on it and totally rewrite the code from scratch.

GW-BASIC / BASICA also only used 64K of RAM no matter how much you had installed.

WordStar 4 came in both CP/M 8-bit and MS-DOS varieties and was a new product, so I wonder what they used to straddle the ISA. (I do have the NIB WS 4 for CP/M--if you ordered the MS-DOS variety, you got a special deal on the CP/M version).

WS 3.3 was the original PC-DOS flavor.

 

[SpidersWeb]

I keep my 5150 as a 256KB unit because I find it more authentic (personal taste, most people wouldn't care) and software made for that generation of computer works fine on this.
But then I also have 5160's with 640KB installed, which have hard drives and can run much later made programs.

If I didn't have those machines, I'd certainly upgrade the 5150.

 

[Retro Canada]

I keep my 5150 as a 256KB unit because I find it more authentic (personal taste, most people wouldn't care) and software made for that generation of computer works fine on this.
But then I also have 5160's with 640KB installed, which have hard drives and can run much later made programs.

If I didn't have those machines, I'd certainly upgrade the 5150.

I keep my 5150 with DOS 3.30 even with the XTIDE interface because to list the directory of drives larger than 32M it takes forever on these machines... and newer DOS would take more space

 

[Trixter]

I use another 286 for later era CGA games that required more power (amazing that someone still made games for CGA-only in 1991).

What games have you found that only support CGA and yet require a 286+ for enough speed?

As for the OP, the best reason to upgrade an XT-class system to 640KB, even if it doesn't have a hard drive, is to cache entire floppies to RAM. Many programs written for 64K or 128K systems do a lot of overlaying and chaining to submodules to get everything to work in a small space, but if you load a disk cache using 300KB or so, eventually the entire disk gets cached in RAM and the program operates much faster as a result (and is less wear and tear on your physical media).

The best disk cache I used to use when I had a dual-drive system was Lightning!. It also had the neat trick of read-ahead caching, where any sector request smaller than a track was fetched by reading the entire track anyway and caching all of it. Some floppy-disk-heavy software loaded noticeably faster doing that.

 

[musicforlife]

What games have you found that only support CGA and yet require a 286+ for enough speed?

Apogee's Monument of Mars, Pharaoh's tomb and Arctic adventure. Then there are also text based games that runs too slow in 5150.

 

[MissArgent]

Upgrading's pretty easy to do and provides more room to work for TSRs and drivers, so there's pretty much no reason not to if a slot or motherboard sockets are spare...Aside from POST taking a year. It tends to do that anyways, though.

 

[nc_mike]

My 5160 PC/XT has 5MB of addressable (extended) RAM, plus another 8M of expanded RAM- all with vintage components from the 80's. I think that might be sufficient

Mike

 

[romanon]

My 5160 PC/XT has 5MB of addressable (extended) RAM, plus another 8M of expanded RAM- all with vintage components from the 80's. I think that might be sufficient

Mike

omg... :eh:

This topic agin? :D

Ok here is my memory equipment and i am satisfied with it enough.

IBM PC 5150 (A) - 64+64kb
IBM PC 5150 (B) - 256+384kb
IBM PC 5160 (64-256k) - 256+256kb
IBM PC 5160 (256-640k) - 640kb
IBM PC 5155 - 256+256kb
IBM PC 5140 - 256+128+128kb
IBM PC 5170 (099) - 512+128kb
IBM PC 5170 (319/339) - 512+640kb
IBM PC 5162 - 640kb

 

[Chuck(G)]

My 5160 PC/XT has 5MB of addressable (extended) RAM, plus another 8M of expanded RAM- all with vintage components from the 80's. I think that might be sufficient

Okay, Mike, you got me with that one. May I assume that the only CPU in your 5160 is not an 8088?

I mean is this a Ferrari with a Corvair nameplate?

 

[Retro Canada]

My 5160 PC/XT has 5MB of addressable (extended) RAM, plus another 8M of expanded RAM- all with vintage components from the 80's. I think that might be sufficient

Mike

You can't have extended memory with a 8088. It doesn't matter how you did it or how you think it works. You clearly does not understand what extended memory is.

The 8088 cannot direct address it because it does not have a protected mode. This is only possible with a 80286 and up (yet in protected mode)

 

[Retro Canada]

Unless you have some sort of In386 or any other card that adds an 286 or 386 processor together the extended memory but you have to disclose this information. A PC/XT alone cannot have extended memory.

 

[Stone]

I believe it's his FRANKENmachine.

 

[ibmapc]

My 5160 PC/XT has 5MB of addressable (extended) RAM, plus another 8M of expanded RAM- all with vintage components from the 80's. I think that might be sufficient

Mike

Okay, Mike, you got me with that one. May I assume that the only CPU in your 5160 is not an 8088?

I mean is this a Ferrari with a Corvair nameplate?

You can't have extended memory with a 8088. It doesn't matter how you did it or how you think it works. You clearly does not understand what extended memory is.

The 8088 cannot direct address it because it does not have a protected mode. This is only possible with a 80286 and up (yet in protected mode)

Unless you have some sort of In386 or any other card that adds an 286 or 386 processor together the extended memory but you have to disclose this information. A PC/XT alone cannot have extended memory.

I believe it's his FRANKENmachine.

This is a quote of nc_mike on another thread. "I upgraded my PC/XT with a 386 InBoard/PC with a 133-pin compatible 486 chip, added an additional 4MB Inboard daughter card". 'nough said!

 

[Caluser2000]

Damn your secret is out mike.

 

[nc_mike]

Just funin' - always stumps someone...

Correct, it is FRANkENmachine - 5160 with the original motherboard and an Inboard/386 PC with 1 MB on board on the In/386 and a 4MB daughter card. The 5160 boots up the first 256KB off of the original 5160 motherboard after which the 386/PC ISA board takes over and initializes the full 5MB. It's definitely not stock, but it is all all 80's vintage IBM-compat PC parts. Can't do much with it with DOS, but it runs Win31 in enhanced mode using the bulk of 5MB well when combined with an XT/IDE and a CF drive.

Mike

 

[Trixter]

Apogee's Monument of Mars, Pharaoh's tomb and Arctic adventure. Then there are also text based games that runs too slow in 5150.

Like ZZT or the Kroz games, I'm guessing. Ironically, all of those work fine on a turbo XT. They just weren't programmed very well.

My 5160 PC/XT has 5MB of addressable (extended) RAM, plus another 8M of expanded RAM

That's not the correct terminology. Your Inboard 386 has 5MB of addressable (extended) RAM, not your PC/XT. Your PC/XT can neither see it nor use it. I can physically place a Core i7-8700K inside my PC/XT case, but that doesn't mean I can now say my PC/XT runs at 35824 MIPS.

 

[romanon]

Apogee's Monument of Mars, Pharaoh's tomb and Arctic adventure. Then there are also text based games that runs too slow in 5150.

Monument of Mars, Pharaoh's tomb and Arctic adventure are definitely not text based games. Even not work with MDA or Hercules graphics...



These games were made in early 90' so they are not primary made for XT systems

 

[Chuck(G)]

Sure Jim, but he can claim that his PC/XT case has 5MB of memory in it.