Ardent Tool of Capitalism

Reply PowerBoard 25

Folks, this is it. The much sought after Reply Corporation upgrade planar for the IBM PS/2 Model 25 and Model 25-286 systems. This board gives you the most performance you can cram into a Model 25, with up to an Intel 486DX4 100MHz CPU. There is nothing higher.*

Thanks to Bob Watts for putting one up for sale complete with manual and all installation parts. I never, ever, thought I would find one.

* Well, almost. A company by the name of PC Enterprises marketed a board known as the Genesis\PC. It's a totally different board than the Reply board. In fact, it is a lot more "clone like" with regards to the BIOS and chipset, but it has a lot more of the "original" PS/2 features, like an earphone plug. There's even a place for a game port and a COM2 port.

Based on content by William R. Walsh (original HERE). Edited by Major Tom.

Reply PowerBoard 25

* not marked

J1 Cyrix 486 CPU select (put jumpers on all pins)
J2 Intel or AMD 486 CPU select (put jumpers on all pins)
J3 VGA IRQ (1-2 Disabled, 2-3 Enabled)
J18 CMOS Clear (1-2 Normal Operation, 2-3 Clear)

Thoughts

I'd highly advise getting the manual at the very least to perform the Reply upgrade planar installation. Having all of the items needed to do the upgrade is not really required — all you really absolutely need is the planar, floppy disk cabling and the riser. A floppy "cable converter" is included with a "new" Reply board, but I didn't have to use it in any of the install scenarios I tried.

I will at some point, though probably not soon, be publishing a guide to installing the Reply board, as well as the PC Enterprises Genesis board.

Upgrading (Video and CPU Upgrade Thoughts)

I have two known attempts to use non-Intel upgrade CPUs on the the Reply Model 25 PowerBoard. The first attempt (using a Kingston TurboChip) by David Beem did not succeed. The planar wouldn't even do POST.

The planar doesn't have a POD style 486 socket, so using a Pentium Overdrive chip is not an option. It looks as though the planar tops out at 100 MHz, but even then that's a big improvement from whatever your Model 25 had beforehand.

My own attempt with an IBM 5x86 CPU at 100 MHz — the system powered up and would display the BIOS copyright, but it froze after that. I suppose that possible CPUID difficulties are the cause of David and I's trouble with non-Intel CPUs.

Purpose of U4? It's a place you can put additional VRAM. Reply seems to have done this on all their boards — they have left this set of pads empty. I would think another 512 KB VRAM chip at this location would give you a nice 1 MB of VRAM, enough to run high color modes with, but nothing beyond 640x480 at 60Hz!