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mbbrutman's mTCP already comes with a bandwidth tester that you can use so that it's a fair comparison against other PCs/XTs. Beyond the 16 bit vs 8 bit transfers, another difference with these cards and your 5150 vs. 5170 is that 80186, V20, and later CPUs all have a single instruction to fill...

Don't know if it has anything to do with your problem but I have a HOT-591P and it admonishes you not to use SIMMs and DIMMs at the same times due to differing voltages. It looks like your board's manual "recommends" against it but it sounds like the previous owner likely had it this way for...

The board was probably intended for the control computer for a Rolm CBX (a PBX)... very common on university campuses (not sure how many are still around?) and I think I've seen their phones at Sears before they closed.

What controller card are you using? I believe one of the pins in the control cable was repurposed as "head select 3" with some previous meaning, so the card may have a "drive has 8 heads or less vs. drive has more than 8 heads" jumper.

The Apple II outputs color and that's part of its claim to fame... only mentioning this as it isn't clear you realize that. This works fine for something like The Oregon Trail. 80-column text on the other hand not so much (unreadable).

Baby AT Pentium boards should be new enough to have all onboard i/o such that all you need is a PCI video card (easy to find) and therefore might be a bit easier to piece together than a 486, yet old enough that the onboard floppy controller still supports dual drives. As if you need an excuse...

I would personally just temporarily move the 5 1/4" floppy drive to another system and then write the disk image or whatever needs to go onto disks from there, in order to bootstrap it. Otherwise you're going to be trying to use a VM or other means to install to the HDD or CF card with the exact...

The suggestion to use CompactFlash is because through an adapter it is IDE-compatible. That is probably why, as you said earlier, you haven't seen an effort to create a custom solutions for PCs. CompactFlash is good enough. An ISA SATA card would be neat, but far beyond my capabilities for sure...

At the software level both serial and parallel DCC are just PPP. There's an exchange at the beginning where one side says CLIENT and the other says CLIENTSERVER (don't remember exactly which order) but then they just switch to PPP, so it's something you can handle with a chat script. There are...

As to another DOS browser, there's a beta Links2 for DOS with graphical mode support (I think it uses Watcom TCP). No JavaScript or CSS, but modern TLS support and PNG support, and realistically needs 16MB of RAM. I doubt there is any hope for JavaScript even if you somehow ported a modern...

Hello Assuming your BIOS is consistent with these listings (https://github.com/kaneton/appendix-bios/blob/master/src/test1.asm#L298) the only thing that can go wrong between 02 and 03 is if the BIOS ROM has an invalid checksum, in which case it halts without beeping.

Are those SIMMs EDO? I can't read the numbers exactly but notice the 1997 date code.

I couldn't get PCem to do it, but it could be that PCem itself already does 101->83 key translation.

Could it simply be that the key that is stuck on this machine is one of those that start with E0 (and the BIOS only prints the first byte of scan code)?

It was indeed the 74F20. Besides one bad 64Kx1 RAM chip, and repairing more damage I had done (ugh--A18 line had been severed somewhere on its way to the expansion slot) it's now good to go. This would have been a 10 minute repair had I skipped all the buffers/latches and been able to go...

If it's a 360K image, are both the media and drive low-density? If the media part is taken care of, you can always temporarily transplant the drive to the 486 to write the image.

When the BBS software shells out to another program such as your QBASIC or any other program, does it still have the serial port open or otherwise attempt to interact with it? Such as an IRQ 4 interrupt handler? If so it seems like any attempt to go around it and mess with the serial port behind...

I don't have a schematic for this board. I'm using the IBM 5160 technical reference and it was close enough to follow along and identify the AD/D 245, the high address latch, low address latch, D/XD 245, and D/MD 245 and started tracing from there. And yeah, I desoldered the 74F20 and out of...

I replaced the 74LS245 and 74LS373 chips with nothing to show for it but three bodge wires to account for the damage I did desoldering. Ugh... So this has been an exercise of learning an XT schematic. On the 74LS245 between the D bus and XD-bus--it seems the DIR is stuck low. DIR is fed from...

The more hardware-oriented posters are going to have to take on this one. All I know is that the 486 prefetch queue is 32 bytes which is quite a while forward, and there are also write buffers so execution continues even when the previous instruction hasn't finished writing to memory. Seems like...